Zheng Li, Tian Wenlong, Ma Junyi, Yu Yang, Xu Xiao-Dong, Han Hainian, Wei Zhiyi, Zhu Jiangfeng
Femtosecond lasers with GHz repetition rate play an important role in scientific and industrial applications, such as spectroscopy, optical frequency combs and GHz-Burst pulse trains for micro-machining in the ablation-cooled regime. Kerr-lens Mode-locked (KLM) technique and passively modelocking based on Semiconductor Saturable Absorber Mirror (SESAM) are the primary methods to generate GHz femtosecond all-solid-state lasers (ASSLs). Kerr-lens mode-locked Ti:Sapphire lasers have made a significant progress benefitting from the high-power green pump lasers, repetition rate up to 10 GHz has been obtained with an average power of 1.2 W. In the early 21st century, ytterbium ion (Yb3+) doped laser crystals and ceramics with emission wavelengths near 1 μm gained attention due to their high conversion efficiency and broad gain-bandwidth. Combining with the customized SESAM and high-power multimode fiber-coupled laser diodes (LD), GHz Yb-doped ASSLs with watt-level average power may be easily attained and have made rapid progress. However, GHz KLM lasers have strict requirements for the cavity design and pump sources. For satisfying mode matching and enhancing the soft aperture effect within the gain medium, a high-brightness pump source with excellent beam quality (M2~1) is desired, such as the single-mode fiber coupled LD, however, the maximum pump power of which is only~1 W. As a result, the average power of GHz KLM femtosecond lasers is typically restricted to few tens of milliwatts, which limits the further applications. In this work, we reported the first GHz high-power KLM Yb:CaYAlO4 laser by using a high-power single-mode fiber laser instead of the low-power single-mode fiber coupled LDs as the pump source. On the basis of ABCD matrices, a simple four-mirror bow-tie ring cavity was built such that the laser mode can match well with the focused pump spot in the crystal. At the pump power of 8 W, stable unidirectional KLM was achieved, the laser had an average power of 2.1 W with a pulse duration of 88 fs and a repetition rate of 1.8 GHz, corresponding to a peak power of 11.57 kW. The high peak power and extremely short pulse duration are crucial for coherent octave-spanning supercontinuum generation. The powerful GHz KLM laser with sub-100 fs pulse duration provides an attractive source for optical frequency combs and micro-machining applications.
{"title":"Sub-100 fs Kerr-lens Mode-locked femtosecond Yb:CaYAlO4 Laser at GHz repetition rate","authors":"Zheng Li, Tian Wenlong, Ma Junyi, Yu Yang, Xu Xiao-Dong, Han Hainian, Wei Zhiyi, Zhu Jiangfeng","doi":"10.7498/aps.72.20222297","DOIUrl":"https://doi.org/10.7498/aps.72.20222297","url":null,"abstract":"Femtosecond lasers with GHz repetition rate play an important role in scientific and industrial applications, such as spectroscopy, optical frequency combs and GHz-Burst pulse trains for micro-machining in the ablation-cooled regime. Kerr-lens Mode-locked (KLM) technique and passively modelocking based on Semiconductor Saturable Absorber Mirror (SESAM) are the primary methods to generate GHz femtosecond all-solid-state lasers (ASSLs). Kerr-lens mode-locked Ti:Sapphire lasers have made a significant progress benefitting from the high-power green pump lasers, repetition rate up to 10 GHz has been obtained with an average power of 1.2 W. In the early 21st century, ytterbium ion (Yb3+) doped laser crystals and ceramics with emission wavelengths near 1 μm gained attention due to their high conversion efficiency and broad gain-bandwidth. Combining with the customized SESAM and high-power multimode fiber-coupled laser diodes (LD), GHz Yb-doped ASSLs with watt-level average power may be easily attained and have made rapid progress. However, GHz KLM lasers have strict requirements for the cavity design and pump sources. For satisfying mode matching and enhancing the soft aperture effect within the gain medium, a high-brightness pump source with excellent beam quality (M2~1) is desired, such as the single-mode fiber coupled LD, however, the maximum pump power of which is only~1 W. As a result, the average power of GHz KLM femtosecond lasers is typically restricted to few tens of milliwatts, which limits the further applications. In this work, we reported the first GHz high-power KLM Yb:CaYAlO4 laser by using a high-power single-mode fiber laser instead of the low-power single-mode fiber coupled LDs as the pump source. On the basis of ABCD matrices, a simple four-mirror bow-tie ring cavity was built such that the laser mode can match well with the focused pump spot in the crystal. At the pump power of 8 W, stable unidirectional KLM was achieved, the laser had an average power of 2.1 W with a pulse duration of 88 fs and a repetition rate of 1.8 GHz, corresponding to a peak power of 11.57 kW. The high peak power and extremely short pulse duration are crucial for coherent octave-spanning supercontinuum generation. The powerful GHz KLM laser with sub-100 fs pulse duration provides an attractive source for optical frequency combs and micro-machining applications.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75540133","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chen Bai-Hui, Shi Bao-Chang, Wang Lei, Chai Zhen-Hua
In this study, we utilize the lattice Boltzmann method to investigate the flow behavior in a two-dimensional trapezoidal cavity, which is under two-sided driving on the upper and lower walls. Our calculations have been accelerated through GPU-CUDA software. We have conducted an analysis of the flow field mode using proper orthogonal decomposition. The effects of various parameters such as Reynolds number (Re) and driving direction on the flow characteristics are examined through numerical simulations. The results show that:(1) for the upper wall drive (T1a), the flow field remains stable within the range of Re from 1000 to 8000. However, when Re=8500, the flow field becomes periodic yet unstable. The velocity phase diagram at the monitoring point is a smooth circle, and the energy of the first two modes has dominated the energy of the whole field. Once Re exceeds 10000, the velocity phase diagram turns irregular and the flow field becomes aperiodic and unsteady. (2) As for the lower wall drive (T1b), the flow is stable within Re 1000-8000, yet when Re=11500, the flow field becomes periodic yet unsteady. The energy of the first three modes appears relatively large. When Re is greater than 12500, the flow field becomes aperiodic and unsteady. At this time, the phase diagram exhibits a smooth circle, with the energy of the first two modes almost entirely dominating the entire energy. (3) For the case of upper and lower walls moving in the same direction with the same speed (T2a), the flow field remains stable when Re changes from 1000 to 10000. When Re is between 12500 to 15000, the flow becomes periodic yet unstable. The velocity phase diagram continues to be a smooth circle, with the first two modes still occupying a large portion of the energy. Once Re surpasses 20000, the energy proportion of the first three modes significantly decreases, and the flow becomes aperiodic and unsteady. (4) For the case in which the upper and lower walls are driven in opposite directions with the same velocity (T2b), the flow field remains stable within Re changes from 1000 to 5000. When Re=6000, the energy of the first mode accounts for 86%, and the flow field becomes periodic yet unstable. When Re surpasses 8000, the energy proportion of the first three modes decreases significantly, and the flow field becomes aperiodic and unsteady.
{"title":"Lattice Boltzmann simulation and analysis of two-dimensional trapezoidal cavity flow based on GPU","authors":"Chen Bai-Hui, Shi Bao-Chang, Wang Lei, Chai Zhen-Hua","doi":"10.7498/aps.72.20230430","DOIUrl":"https://doi.org/10.7498/aps.72.20230430","url":null,"abstract":"In this study, we utilize the lattice Boltzmann method to investigate the flow behavior in a two-dimensional trapezoidal cavity, which is under two-sided driving on the upper and lower walls. Our calculations have been accelerated through GPU-CUDA software. We have conducted an analysis of the flow field mode using proper orthogonal decomposition. The effects of various parameters such as Reynolds number (Re) and driving direction on the flow characteristics are examined through numerical simulations. The results show that:(1) for the upper wall drive (T1a), the flow field remains stable within the range of Re from 1000 to 8000. However, when Re=8500, the flow field becomes periodic yet unstable. The velocity phase diagram at the monitoring point is a smooth circle, and the energy of the first two modes has dominated the energy of the whole field. Once Re exceeds 10000, the velocity phase diagram turns irregular and the flow field becomes aperiodic and unsteady. (2) As for the lower wall drive (T1b), the flow is stable within Re 1000-8000, yet when Re=11500, the flow field becomes periodic yet unsteady. The energy of the first three modes appears relatively large. When Re is greater than 12500, the flow field becomes aperiodic and unsteady. At this time, the phase diagram exhibits a smooth circle, with the energy of the first two modes almost entirely dominating the entire energy. (3) For the case of upper and lower walls moving in the same direction with the same speed (T2a), the flow field remains stable when Re changes from 1000 to 10000. When Re is between 12500 to 15000, the flow becomes periodic yet unstable. The velocity phase diagram continues to be a smooth circle, with the first two modes still occupying a large portion of the energy. Once Re surpasses 20000, the energy proportion of the first three modes significantly decreases, and the flow becomes aperiodic and unsteady. (4) For the case in which the upper and lower walls are driven in opposite directions with the same velocity (T2b), the flow field remains stable within Re changes from 1000 to 5000. When Re=6000, the energy of the first mode accounts for 86%, and the flow field becomes periodic yet unstable. When Re surpasses 8000, the energy proportion of the first three modes decreases significantly, and the flow field becomes aperiodic and unsteady.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73683908","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Di Shu-Hong, Zhang Yang, Yang Hui-Jing, Cui Nai-Zhong, Li Yan-Kun, Liu Hui-Yuan, Li Ling-Li, Shi Feng-Liang, Jia Yu-Xuan
Because of the difficulty in measuring the cluster isotope displacement and identifying its causes, the resonance dissociation spectra, the moment shift and Zeeman energy shift of isotope cluster 87,85Rbn(n=1,2, 3,..., 13) are obtained by the combination of optical magnetic resonance and thermal dissociation techniques in this study. The quantitative calculation is carried out based on the conceptual model of the giant atom, and the results are in strict agreement with the measured results, which shows that rubidium clusters can be analyzed as giant-like atoms. Furthermore, 5s electron shell level structure of the rubidium cluster 87,85Rbn(n=1,2, 3,..., 92) is calculated using Zeeman level interval model. It is found that the main order and step distance of the 5s electron shell structure are similar to those of 3s single electron shell structure of sodium cluster in spherical symmetric. It is confirmed that the structure of the 5s electron shell of the rubidium cluster is determined by the largest energy gap of total Zeeman levels and the characteristic peaks of odd and even alternating and anomalous magnetic moments of special numbers such as n=2 are caused by the intrinsic properties of electrons and molecular structures. It is also found that 87Rbn and 85Rbn level shell structure is strictly consistent with the ratio of 3/2 magnitude relationship, and there are abnormal differences in spectral center frequency and broadening, which may be directly related to the 85,87Rb nuclide on the closed surface of the core-shell.
{"title":"Quantitative study on isotope effect of rubidium clusters","authors":"Di Shu-Hong, Zhang Yang, Yang Hui-Jing, Cui Nai-Zhong, Li Yan-Kun, Liu Hui-Yuan, Li Ling-Li, Shi Feng-Liang, Jia Yu-Xuan","doi":"10.7498/aps.72.20230778","DOIUrl":"https://doi.org/10.7498/aps.72.20230778","url":null,"abstract":"Because of the difficulty in measuring the cluster isotope displacement and identifying its causes, the resonance dissociation spectra, the moment shift and Zeeman energy shift of isotope cluster 87,85Rbn(n=1,2, 3,..., 13) are obtained by the combination of optical magnetic resonance and thermal dissociation techniques in this study. The quantitative calculation is carried out based on the conceptual model of the giant atom, and the results are in strict agreement with the measured results, which shows that rubidium clusters can be analyzed as giant-like atoms. Furthermore, 5s electron shell level structure of the rubidium cluster 87,85Rbn(n=1,2, 3,..., 92) is calculated using Zeeman level interval model. It is found that the main order and step distance of the 5s electron shell structure are similar to those of 3s single electron shell structure of sodium cluster in spherical symmetric. It is confirmed that the structure of the 5s electron shell of the rubidium cluster is determined by the largest energy gap of total Zeeman levels and the characteristic peaks of odd and even alternating and anomalous magnetic moments of special numbers such as n=2 are caused by the intrinsic properties of electrons and molecular structures. It is also found that 87Rbn and 85Rbn level shell structure is strictly consistent with the ratio of 3/2 magnitude relationship, and there are abnormal differences in spectral center frequency and broadening, which may be directly related to the 85,87Rb nuclide on the closed surface of the core-shell.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72409684","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gao Ming-Zhu, Liu Chun-Liang, Wang Hong-Guang, Li Yong-Dong, Lin Shu, Zhai Yong-Gui
As a regulator of cation activity in living cells, KcsA (K+ Conduction and Selectivity Architecture) potassium channel plays an important role in the depolarization and repolarization of nerve cell action potential. In this paper, Brownian Dynamics (BD) method is used to simulate the electrical characteristics of the actual KcsA potassium channel systematically. The PMF of ions in the channel under electrostatic field, the current-voltage characteristic curve of symmetric solution and asymmetric solution, the ion concentration distribution curve in the axial direction of the channel, and the conduction-concentration curve are obtained. The results showed that the SF region of KcsA potassium ion channel blocked the passage of Cl- basically, showing a special selection characteristic of the passage of K+; Its current-voltage curve basically presents a linear distribution, and the conductivity-concentration curve presents a trend of first increasing and then flattening. The basic law is consistent with the experimental phenomenon. In addition, the influence of the specific intensity THz field on the channel K+ current is also simulated and analyzed. Compared with the electrostatic field of the same amplitude, the selected 0.6/1.2/5THz terahertz field can reduce the PMF by affecting the interaction potential energy between ion pairs, thereby increasing the K+ current. The research in this paper not only deepens the understanding of the regularity of KcsA potassium ion channels, but also provides a new idea for the study of other types of ion channels and the influence of terahertz field on the characteristics of ion channels.
KcsA (K+ Conduction and Selectivity Architecture)钾离子通道作为活细胞中阳离子活性的调节剂，在神经细胞动作电位的去极化和复极化过程中起着重要作用。本文采用布朗动力学方法系统地模拟了实际KcsA钾通道的电特性。得到了静电场作用下通道内离子的PMF、对称溶液和非对称溶液的电流-电压特性曲线、通道轴向离子浓度分布曲线和电导-浓度曲线。结果表明:KcsA钾离子通道的SF区基本阻断Cl-的通过，对K+的通过表现出特殊的选择特性;其电流-电压曲线基本呈线性分布，电导率-浓度曲线呈先升高后趋于平缓的趋势。该基本定律与实验现象是一致的。此外，还模拟分析了比强太赫兹场对通道K+电流的影响。与相同振幅的静电场相比，选择0.6/1.2/5THz太赫兹场可以通过影响离子对之间的相互作用势能来降低PMF，从而增加K+电流。本文的研究不仅加深了对KcsA钾离子通道的规律性的认识，而且为研究其他类型的离子通道以及太赫兹场对离子通道特性的影响提供了新的思路。
{"title":"Brownian dynamics simulation of electrical properties of KcsA potassium ion channel","authors":"Gao Ming-Zhu, Liu Chun-Liang, Wang Hong-Guang, Li Yong-Dong, Lin Shu, Zhai Yong-Gui","doi":"10.7498/aps.72.20230118","DOIUrl":"https://doi.org/10.7498/aps.72.20230118","url":null,"abstract":"As a regulator of cation activity in living cells, KcsA (K+ Conduction and Selectivity Architecture) potassium channel plays an important role in the depolarization and repolarization of nerve cell action potential. In this paper, Brownian Dynamics (BD) method is used to simulate the electrical characteristics of the actual KcsA potassium channel systematically. The PMF of ions in the channel under electrostatic field, the current-voltage characteristic curve of symmetric solution and asymmetric solution, the ion concentration distribution curve in the axial direction of the channel, and the conduction-concentration curve are obtained. The results showed that the SF region of KcsA potassium ion channel blocked the passage of Cl- basically, showing a special selection characteristic of the passage of K+; Its current-voltage curve basically presents a linear distribution, and the conductivity-concentration curve presents a trend of first increasing and then flattening. The basic law is consistent with the experimental phenomenon. In addition, the influence of the specific intensity THz field on the channel K+ current is also simulated and analyzed. Compared with the electrostatic field of the same amplitude, the selected 0.6/1.2/5THz terahertz field can reduce the PMF by affecting the interaction potential energy between ion pairs, thereby increasing the K+ current. The research in this paper not only deepens the understanding of the regularity of KcsA potassium ion channels, but also provides a new idea for the study of other types of ion channels and the influence of terahertz field on the characteristics of ion channels.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78449710","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pan Zhi-Peng, Li Wei, Lv Jia-Gang, Nie Yu-Wei, Zhong Li, Liu Su-ping, Ma Xiao-Yu
As the key part of Vertical Cavity Surface Emitting Laser (VCSEL), active region will seriously affect the threshold and efficiency of the device. To obtain appropriate laser wavelength and material gain, the In0.18Ga0.82As strain compensated quantum well is optimized design. The relationship between the lasing wavelength of multiple quantum wells (MQWs) and the thickness is calculated. Take into account the influence between the active region temperature and the lasing wavelength, the thickness of the quantum well is chose as 6 nm, the quantum barrier thickness is chose as 8 nm, corresponding to the lasing wavelength of 929 nm. The material gain characteristics of the MQWs under different temperature are simulated by Rsoft. The material gain exceeds 3300 /cm at 300 K, and the temperature drift coefficient of the peak wavelength is 0.3 nm/K. In this paper, Al0.09Ga0.91As and Al0.89Ga0.11As are selected as high and low refractive index materials of Distributed Braagg Reflector (DBR), and 20 nm graded layer is inserted between two types of materials. The influence of the graded layer thickness of DBR on the valence band barrier and reflection spectrum is calculated and analyzed. The increase of graded layer thickness can lead to the decrease of band barrier peak and the decrease of reflection spectrum bandwidth. The reflection spectrum and phase spectrum of P-DBR and N-DBR are calculated by the transmission matrix mode (TMM), the reflectance of DBR is over 99% and the phase shift is zero at 940 nm. The optical field distribution of the whole VCSEL structure is simulated, in which the standing wave peak overlaps with the active region, and the maximum gain can be obtained. Based on the finite element method (FEM), the effect of oxidation confined layer on the injection current is simulated. The current in the active region is effectively limited to the position corresponding to the oxidation confined hole, and its current density is stronger and more uniform. The optical field distribution in different modes of PC-VCSEL is simulated, different modes have different resonant wavelengths. The quality factor Q in different modes of VCSEL and Photonic Crystal-Vertical Cavity Surface Emitting Laser (PC-VCSEL) is calculated, Q of the fundamental mode is higher than higher transverse mode. It is demonstrated that the photonic crystal air hole structure can realize the output of basic transverse mode by increasing the loss of high order transverse mode. VCSEL and PC-VCSEL with oxidation hole size of 22 μm are successfully fabricated, in which the photonic crystal period is 5 μm, the air pore diameter is 2.5 μm and the etching depth is 2 μm. Under continuous current test, the maximum slope efficiency of VCSEL is 0.66 mW/mA, the output power is 9.3 mW at 22 mA, and the lasing wavelength is 948.64 nm at 20 mA injection current. Multiple wavelengths and large spectrum width is observed in the spectrum of VSCEL, which is an obvious multi-transverse mode. The maxi
{"title":"Design and Fabrication of 940 nm VCSEL Single-emitter Device","authors":"Pan Zhi-Peng, Li Wei, Lv Jia-Gang, Nie Yu-Wei, Zhong Li, Liu Su-ping, Ma Xiao-Yu","doi":"10.7498/aps.72.20230297","DOIUrl":"https://doi.org/10.7498/aps.72.20230297","url":null,"abstract":"As the key part of Vertical Cavity Surface Emitting Laser (VCSEL), active region will seriously affect the threshold and efficiency of the device. To obtain appropriate laser wavelength and material gain, the In0.18Ga0.82As strain compensated quantum well is optimized design. The relationship between the lasing wavelength of multiple quantum wells (MQWs) and the thickness is calculated. Take into account the influence between the active region temperature and the lasing wavelength, the thickness of the quantum well is chose as 6 nm, the quantum barrier thickness is chose as 8 nm, corresponding to the lasing wavelength of 929 nm. The material gain characteristics of the MQWs under different temperature are simulated by Rsoft. The material gain exceeds 3300 /cm at 300 K, and the temperature drift coefficient of the peak wavelength is 0.3 nm/K. In this paper, Al0.09Ga0.91As and Al0.89Ga0.11As are selected as high and low refractive index materials of Distributed Braagg Reflector (DBR), and 20 nm graded layer is inserted between two types of materials. The influence of the graded layer thickness of DBR on the valence band barrier and reflection spectrum is calculated and analyzed. The increase of graded layer thickness can lead to the decrease of band barrier peak and the decrease of reflection spectrum bandwidth. The reflection spectrum and phase spectrum of P-DBR and N-DBR are calculated by the transmission matrix mode (TMM), the reflectance of DBR is over 99% and the phase shift is zero at 940 nm. The optical field distribution of the whole VCSEL structure is simulated, in which the standing wave peak overlaps with the active region, and the maximum gain can be obtained. Based on the finite element method (FEM), the effect of oxidation confined layer on the injection current is simulated. The current in the active region is effectively limited to the position corresponding to the oxidation confined hole, and its current density is stronger and more uniform. The optical field distribution in different modes of PC-VCSEL is simulated, different modes have different resonant wavelengths. The quality factor Q in different modes of VCSEL and Photonic Crystal-Vertical Cavity Surface Emitting Laser (PC-VCSEL) is calculated, Q of the fundamental mode is higher than higher transverse mode. It is demonstrated that the photonic crystal air hole structure can realize the output of basic transverse mode by increasing the loss of high order transverse mode. VCSEL and PC-VCSEL with oxidation hole size of 22 μm are successfully fabricated, in which the photonic crystal period is 5 μm, the air pore diameter is 2.5 μm and the etching depth is 2 μm. Under continuous current test, the maximum slope efficiency of VCSEL is 0.66 mW/mA, the output power is 9.3 mW at 22 mA, and the lasing wavelength is 948.64 nm at 20 mA injection current. Multiple wavelengths and large spectrum width is observed in the spectrum of VSCEL, which is an obvious multi-transverse mode. The maxi","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75941294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fluorination of graphene is one of the most effective methods to improve the corrosion protection of graphene coatings. In this paper, the diffusion and penetration behaviors of O atoms on fully fluorinated graphene (CF) and partially fluorinated graphene (C4F) were investigated using the NEB transition state search method. The effects of F atoms on the corrosion resistance of fluorinated graphene films were analyzed either. The results show that the adsorption of F atoms can effectively inhibit the diffusion of O atoms on graphene. On C4F, the F atoms are distributed in a para-top position, which greatly increases the surface diffusion energy barrier of O atoms. Moreover, it is difficult for the adsorbed O atoms to diffuse to different sp2 C rings through the obstruction of F atoms. The energy barrier of the horizontal diffusion of O atoms even reaches 2.69 eV in CF. And with the increase of F atoms, the stable structure of graphene is gradually destroyed, the barrier ability of C-atom layer for penetration behaviors of O atoms is greatly reduced. Furthermore, the interfacial adhesion work of pure graphene, CF and C4F films with Cu(111) surfaces were calculated, as well as the electronic structures of the composite interface using first-principles calculations. The interfacial adhesion work of the Cu/G, Cu/C4F and Cu/CF interfaces are 2.626J/m2、3.529J/m2and 3.559J/m2, respectively. The calculations show that the bonding of C4F and C4F with Cu substrate are more strong than pure graphene with Cu substrate, and the interfacial adhesion work increase with increasing of F atom adsorption concentration. The calculation of the density of states also conform stronger interaction between Cu and C atoms of the Cu/C4F interface than that of the Cu/CF interface. Bader charge analysis show increased charge transfer at both the Cu/C4F and Cu/CF interfaces comparing with the Cu/G interface, and Cu/C4F interface has more charge transfer, in which Cu-C bonds are formed.
{"title":"First-principles calculations on O-atom diffusion on fluorinated graphene","authors":"Hailin Yang, Qili Chen, Xing Gu, Ning Lin","doi":"10.7498/aps.72.20221630","DOIUrl":"https://doi.org/10.7498/aps.72.20221630","url":null,"abstract":"Fluorination of graphene is one of the most effective methods to improve the corrosion protection of graphene coatings. In this paper, the diffusion and penetration behaviors of O atoms on fully fluorinated graphene (CF) and partially fluorinated graphene (C4F) were investigated using the NEB transition state search method. The effects of F atoms on the corrosion resistance of fluorinated graphene films were analyzed either. The results show that the adsorption of F atoms can effectively inhibit the diffusion of O atoms on graphene. On C4F, the F atoms are distributed in a para-top position, which greatly increases the surface diffusion energy barrier of O atoms. Moreover, it is difficult for the adsorbed O atoms to diffuse to different sp2 C rings through the obstruction of F atoms. The energy barrier of the horizontal diffusion of O atoms even reaches 2.69 eV in CF. And with the increase of F atoms, the stable structure of graphene is gradually destroyed, the barrier ability of C-atom layer for penetration behaviors of O atoms is greatly reduced. Furthermore, the interfacial adhesion work of pure graphene, CF and C4F films with Cu(111) surfaces were calculated, as well as the electronic structures of the composite interface using first-principles calculations. The interfacial adhesion work of the Cu/G, Cu/C4F and Cu/CF interfaces are 2.626J/m2、3.529J/m2and 3.559J/m2, respectively. The calculations show that the bonding of C4F and C4F with Cu substrate are more strong than pure graphene with Cu substrate, and the interfacial adhesion work increase with increasing of F atom adsorption concentration. The calculation of the density of states also conform stronger interaction between Cu and C atoms of the Cu/C4F interface than that of the Cu/CF interface. Bader charge analysis show increased charge transfer at both the Cu/C4F and Cu/CF interfaces comparing with the Cu/G interface, and Cu/C4F interface has more charge transfer, in which Cu-C bonds are formed.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76115412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
High-order harmonic generation (HHG) from the molecular ions stretched to large internuclear distances is studied numerically and analytically in this work. We focus on the fine structure of the HHG spectrum related to the contribution of short electron trajectory. In our numerically solving the time-dependent Schrodinger equation (TDSE), we use a trajectory-dependent filtering procedure to separate the short-trajectory contribution from other contributions of long trajectory and multiple returns. Our TDSE results reveal that the short-trajectory HHG spectra of molecular ion with larger internuclear distance show some complex interference structures characterized by some remarkable dips, and that the position of the dip is sensitive to the laser parameters. With a developed model arising from strong-field approximation (SFA), we are able to identify the physical origins of the complex interference structures. In this model considered is the charge-resonance effect which induces the strong coupling between the ground state and the first excited state of the molecular ion at large internuclear distance. In this model, the well-known effect of two-center interference occurs in the form of the canonical momentum instead of the momentum related to the instantaneous velocity of the electron in the general SFA. It is shown that some dips in TDSE results arise from two-center interference of the electronic wave between these two atomic cores of the molecule in the ionization process, while others come from that in the recombination process. These ionization and recombination dips alternately appear in the HHG spectra from the formed complex interference structures. The main differences between the interference effects in the ionization process and the recombination process are twofold. Firstly, in the ionization process, the destructive two-center interference strongly suppresses the forming of the continuum wavepacket, while in the recombination process, the recombination of the rescattering electron with other bound eigenstates with small weights can also contribute to HHG bedsides the recombination of the ground state with the first excited state with large weights. As a result, in TDSE results, the ionization dips are deeper and more remarkable than the recombination ones. Secondly, in the recombination process, the Coulomb acceleration remarkably changes the de Broglie wavelength of the rescattering electron and therefore changes the position of the interference-induced dip. While in the ionization process, the Coulomb potential plays a small role in the interference effect. As a result, the interference dips in the ionization process and the recombination process differ from each other.
{"title":"Physical origins of complex interference structures in harmonic emission from molecular ions stretched to large internuclear distances","authors":"Weiyan Li, Na Liu, Shang Wang","doi":"10.7498/aps.72.20222410","DOIUrl":"https://doi.org/10.7498/aps.72.20222410","url":null,"abstract":"High-order harmonic generation (HHG) from the molecular ions stretched to large internuclear distances is studied numerically and analytically in this work. We focus on the fine structure of the HHG spectrum related to the contribution of short electron trajectory. In our numerically solving the time-dependent Schrodinger equation (TDSE), we use a trajectory-dependent filtering procedure to separate the short-trajectory contribution from other contributions of long trajectory and multiple returns. Our TDSE results reveal that the short-trajectory HHG spectra of molecular ion with larger internuclear distance show some complex interference structures characterized by some remarkable dips, and that the position of the dip is sensitive to the laser parameters. With a developed model arising from strong-field approximation (SFA), we are able to identify the physical origins of the complex interference structures. In this model considered is the charge-resonance effect which induces the strong coupling between the ground state and the first excited state of the molecular ion at large internuclear distance. In this model, the well-known effect of two-center interference occurs in the form of the canonical momentum instead of the momentum related to the instantaneous velocity of the electron in the general SFA. It is shown that some dips in TDSE results arise from two-center interference of the electronic wave between these two atomic cores of the molecule in the ionization process, while others come from that in the recombination process. These ionization and recombination dips alternately appear in the HHG spectra from the formed complex interference structures. The main differences between the interference effects in the ionization process and the recombination process are twofold. Firstly, in the ionization process, the destructive two-center interference strongly suppresses the forming of the continuum wavepacket, while in the recombination process, the recombination of the rescattering electron with other bound eigenstates with small weights can also contribute to HHG bedsides the recombination of the ground state with the first excited state with large weights. As a result, in TDSE results, the ionization dips are deeper and more remarkable than the recombination ones. Secondly, in the recombination process, the Coulomb acceleration remarkably changes the de Broglie wavelength of the rescattering electron and therefore changes the position of the interference-induced dip. While in the ionization process, the Coulomb potential plays a small role in the interference effect. As a result, the interference dips in the ionization process and the recombination process differ from each other.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75027004","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fan Wen-Xin, Wang Min-Jie, Jiao Hao-Le, Lu Jia-Jin, Liu Hai-Long, Yang Zhi-Fang, Xi Meng-Qi, Li Shu-Jing, Wang Hai
Quantum communication holds promise for absolutely secure information transmission. However, the direct transmission distance of quantum states is limited by the no-cloning theorem and transmission loss. To overcome these problems, Duan et al. proposed a promising quantum repeater scheme, DLCZ protocol (for Duan, Lukin, Cirac, and Zoller, in 2001), in which linear optics and atomic ensembles are used to combine entanglement generation and quantum memory into a single node. A quantum memory with highly retrieval efficiency is beneficial to increase the rate of entanglement swapping, achieving high-speed entanglement distribution. Up to now, high-efficiency quantum memories have been realized using high-optical-depth atomic ensembles or by coupling atomic ensembles with a medium-finesse optical cavity. However, the effect of the waist ratio of read beam and anti-Stokes photon modes on intrinsic retrieval efficiency has not been studied in detail. Here, we study the dependence of intrinsic retrieval efficiency on the waist ratio of read beam and anti-Stokes photon modes in cavity-enhanced quantum memory.In this work, a 87Rb atomic ensemble, that is placed at the center of a passively stabilized polarization interferometer (BD1,2), is used as quantum memory. Firstly, the ensemble is captured through magneto-optical trapping (MOT) and prepared to the Zeeman sub-level of ground state $|5{S_{1/2}},F = 1,m = 0rangle$. Then, a weak write pulse, with frequency red-detuned from the $|5{S_{1/2}},F = 1,m = 0rangle$$ to |5{P_{1/2}},F' = 1,m = 1rangle $ transition by 110 MHz, illuminates the atoms and induces spontaneous Raman scattering out a Stokes photon. In this regime of weak excitation, the detection of a Stokes photon heralds the storage of a single spin wave $|5{S_{1/2}},F = 1,m = 0rangle$$ leftrightarrow |5{S_{1/2}},F = 2,m = 0rangle $ ($|5{S_{1/2}},F = 1,m = 0rangle$$leftrightarrow |5{S_{1/2}},F = 2,m = 2rangle $) distributed among the whole ensemble. After a programmable delay, a read pulse, red-detuned from the $|5{S_{1/2}},F = 2,m = 0rangle to |5{P_{1/2}},F' = 2,m = - 1rangle $ transition by 110MHz, transfer this spin wave into an anti-Stokes photon. We detect the Stokes photons and anti-Stokes photons with polarization ${sigma ^ + }$, which means all the spin-wave are stored in a magnetic-field-insensitive state to reduce the decoherence caused by the stray magnetic fields. In order to increase the intrinsic retrieval efficiency, the atomic ensemble is placed in a ring cavity. The cavity length is 4 m, the finesse is measured to be ~15, and the escape efficiency of ring cavity is 52.9%. Both Stokes and anti-Stokes photon qubits are required to resonate with the ring cavity. To meet this requirement, a cavity-locking beam is injected into the cavity to stabilize the cavity length using a Pound-Drever-Hall locking scheme. Finally, we fixed the Stokes (anti-Stokes) photon modes waist and changed the waist ratio by changing the write beam (read beam)
量子通信有望实现绝对安全的信息传输。然而，量子态的直接传输距离受到不可克隆定理和传输损耗的限制。为了克服这些问题，Duan等人提出了一种很有前途的量子中继器方案，DLCZ协议(为Duan、Lukin、Cirac和Zoller于2001年提出)，其中使用线性光学和原子系综将纠缠产生和量子存储结合到单个节点中。具有高检索效率的量子存储器有利于提高纠缠交换速率，实现高速纠缠分配。到目前为止，高效量子存储主要是利用高光深原子系综或将原子系综与中等精细度的光腔耦合实现的。然而，读光束和反斯托克斯光子模式腰比对本征检索效率的影响尚未得到详细的研究。本文研究了腔增强量子存储中读光束和反stokes光子模式腰比对本征检索效率的影响。在这项工作中，放置在被动稳定偏振干涉仪(BD1,2)中心的87Rb原子系综被用作量子存储器。首先，通过磁光捕获(MOT)捕获该系综，并将其制备到基态的塞曼亚能级$|5{S_{1/2}},F = 1,m = 0rangle$。然后，一个频率从$|5{S_{1/2}},F = 1,m = 0rangle$$ to |5{P_{1/2}},F' = 1,m = 1rangle $跃迁红失调谐110兆赫兹的弱写入脉冲，照亮原子并诱导自发拉曼散射出一个斯托克斯光子。在这种弱激发状态下，斯托克斯光子的探测预示着单个自旋波$|5{S_{1/2}},F = 1,m = 0rangle$$ leftrightarrow |5{S_{1/2}},F = 2,m = 0rangle $ ($|5{S_{1/2}},F = 1,m = 0rangle$$leftrightarrow |5{S_{1/2}},F = 2,m = 2rangle $)分布在整个系综中的存储。经过可编程延迟后，读取脉冲，从$|5{S_{1/2}},F = 2,m = 0rangle to |5{P_{1/2}},F' = 2,m = - 1rangle $跃迁红失调谐110MHz，将该自旋波转换为反斯托克斯光子。我们检测到Stokes光子和反Stokes光子的极化${sigma ^ + }$，这意味着所有的自旋波都以磁场不敏感的状态存储，以减少杂散磁场引起的退相干。为了提高本征检索效率，原子系综被放置在环形腔中。环形腔长度为4 m，精密度为15，环形腔的逃逸效率为52.9%. Both Stokes and anti-Stokes photon qubits are required to resonate with the ring cavity. To meet this requirement, a cavity-locking beam is injected into the cavity to stabilize the cavity length using a Pound-Drever-Hall locking scheme. Finally, we fixed the Stokes (anti-Stokes) photon modes waist and changed the waist ratio by changing the write beam (read beam) waist.The experiment result show that when the waist ratio of read beam and anti-Stokes photon modes is 3, the intrinsic retrieval efficiency is up to 68.9±1.6% and normalized cross-correlation function g(2) reaches 26.5±1.9. We built a theoretical model, the intrinsic retrieval efficiency increases with the rise of the waist ratio, which show that the intrinsic retrieval efficiency is up to the peak when the waist ratio is 3, and the intrinsic retrieval efficiency tends to be stable when the waist ratio continues to increase. The experiment agrees with the theory. In the future, we will improve the intrinsic retrieval efficiency by enhance the fineness of the optical cavity with optimizing the cavity parameters.
{"title":"Dependence of retrieval efficiency on the waist ratio of read beam and anti-Stokes photon modes in cavity-enhanced quantum memory","authors":"Fan Wen-Xin, Wang Min-Jie, Jiao Hao-Le, Lu Jia-Jin, Liu Hai-Long, Yang Zhi-Fang, Xi Meng-Qi, Li Shu-Jing, Wang Hai","doi":"10.7498/aps.72.20230966","DOIUrl":"https://doi.org/10.7498/aps.72.20230966","url":null,"abstract":"Quantum communication holds promise for absolutely secure information transmission. However, the direct transmission distance of quantum states is limited by the no-cloning theorem and transmission loss. To overcome these problems, Duan et al. proposed a promising quantum repeater scheme, DLCZ protocol (for Duan, Lukin, Cirac, and Zoller, in 2001), in which linear optics and atomic ensembles are used to combine entanglement generation and quantum memory into a single node. A quantum memory with highly retrieval efficiency is beneficial to increase the rate of entanglement swapping, achieving high-speed entanglement distribution. Up to now, high-efficiency quantum memories have been realized using high-optical-depth atomic ensembles or by coupling atomic ensembles with a medium-finesse optical cavity. However, the effect of the waist ratio of read beam and anti-Stokes photon modes on intrinsic retrieval efficiency has not been studied in detail. Here, we study the dependence of intrinsic retrieval efficiency on the waist ratio of read beam and anti-Stokes photon modes in cavity-enhanced quantum memory.In this work, a 87Rb atomic ensemble, that is placed at the center of a passively stabilized polarization interferometer (BD1,2), is used as quantum memory. Firstly, the ensemble is captured through magneto-optical trapping (MOT) and prepared to the Zeeman sub-level of ground state $|5{S_{1/2}},F = 1,m = 0rangle$. Then, a weak write pulse, with frequency red-detuned from the $|5{S_{1/2}},F = 1,m = 0rangle$$ to |5{P_{1/2}},F' = 1,m = 1rangle $ transition by 110 MHz, illuminates the atoms and induces spontaneous Raman scattering out a Stokes photon. In this regime of weak excitation, the detection of a Stokes photon heralds the storage of a single spin wave $|5{S_{1/2}},F = 1,m = 0rangle$$ leftrightarrow |5{S_{1/2}},F = 2,m = 0rangle $ ($|5{S_{1/2}},F = 1,m = 0rangle$$leftrightarrow |5{S_{1/2}},F = 2,m = 2rangle $) distributed among the whole ensemble. After a programmable delay, a read pulse, red-detuned from the $|5{S_{1/2}},F = 2,m = 0rangle to |5{P_{1/2}},F' = 2,m = - 1rangle $ transition by 110MHz, transfer this spin wave into an anti-Stokes photon. We detect the Stokes photons and anti-Stokes photons with polarization ${sigma ^ + }$, which means all the spin-wave are stored in a magnetic-field-insensitive state to reduce the decoherence caused by the stray magnetic fields. In order to increase the intrinsic retrieval efficiency, the atomic ensemble is placed in a ring cavity. The cavity length is 4 m, the finesse is measured to be ~15, and the escape efficiency of ring cavity is 52.9%. Both Stokes and anti-Stokes photon qubits are required to resonate with the ring cavity. To meet this requirement, a cavity-locking beam is injected into the cavity to stabilize the cavity length using a Pound-Drever-Hall locking scheme. Finally, we fixed the Stokes (anti-Stokes) photon modes waist and changed the waist ratio by changing the write beam (read beam) ","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72702810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The mechanism of photon acceleration driven by the near-forward scattering (NFS) in intense laser under-dense plasma interaction has been studied by particle-in-cell (PIC) simulation. This mechanism utilizes tunneling ionization effect to stimulate electron plasma waves when the intense laser pulse propagates in under-dense plasmas. The electron plasma density is inhomogeneous both in longitudinal and transverse direction. In longitudinal direction, a steep ionized electron density front is generated by incident laser ionizing the helium gas. Around the ionization front, the incident laser interacts with electron plasma waves and generates the first kind of NFS waves. The frequency of NFS waves increases compared to the laser frequency. This is the first characteristic peak in the frequency spectrum. In transverse direction, the electron plasma waves have different phase velocities which makes the incident laser pulse undergoes NFS process and upshifts its frequency. This is the second characteristic peak in the frequency spectrum. Due to that the electron density inhomogeneity is much larger than the electron density perturbation of electron plasma wave, the scattering model and dispersion relationships, which are based on perturbation theory like the stimulated Raman scattering, are no longer applicable in this case. Our further study shows that the incident laser, electron density plasma waves and NFS waves still satisfy the energy conservation and momentum conservation which leads to the three-waves matching conditions of NFS process for inhomogeneous electron density. This can explain the appearance of two characteristic peaks in the frequency spectrum and their growth in the wave-vector space. This study has significant reference for the spectrum evolution when the intense laser pulse propagates in under-dense plasmas.
{"title":"The Study of Photon Acceleration Driven by the Near-forward Scattering in the Intense Laser Under-dense Plasma Interaction","authors":"Yue Dong-Ning, Dong Quan-Li, Chen Min, Zhao Yao, Geng Pan-Fei, Yuan Xiao-hui, Sheng Zheng-Ming, Zhang Jie","doi":"10.7498/aps.72.20222014","DOIUrl":"https://doi.org/10.7498/aps.72.20222014","url":null,"abstract":"The mechanism of photon acceleration driven by the near-forward scattering (NFS) in intense laser under-dense plasma interaction has been studied by particle-in-cell (PIC) simulation. This mechanism utilizes tunneling ionization effect to stimulate electron plasma waves when the intense laser pulse propagates in under-dense plasmas. The electron plasma density is inhomogeneous both in longitudinal and transverse direction. In longitudinal direction, a steep ionized electron density front is generated by incident laser ionizing the helium gas. Around the ionization front, the incident laser interacts with electron plasma waves and generates the first kind of NFS waves. The frequency of NFS waves increases compared to the laser frequency. This is the first characteristic peak in the frequency spectrum. In transverse direction, the electron plasma waves have different phase velocities which makes the incident laser pulse undergoes NFS process and upshifts its frequency. This is the second characteristic peak in the frequency spectrum. Due to that the electron density inhomogeneity is much larger than the electron density perturbation of electron plasma wave, the scattering model and dispersion relationships, which are based on perturbation theory like the stimulated Raman scattering, are no longer applicable in this case. Our further study shows that the incident laser, electron density plasma waves and NFS waves still satisfy the energy conservation and momentum conservation which leads to the three-waves matching conditions of NFS process for inhomogeneous electron density. This can explain the appearance of two characteristic peaks in the frequency spectrum and their growth in the wave-vector space. This study has significant reference for the spectrum evolution when the intense laser pulse propagates in under-dense plasmas.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77563942","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
He Ya-Ping, Chen Ming-Xia, Pan Jie-Feng, Li Dong, Lin Gang-Jun, Huang Xin-Hong
Nanothick semiconductors can grow orderly along a desired direction with the help of modern materials growth technology such as molecular beam epitaxy, which allows researchers to fabricate the so-called layered semiconductor nanostructure (LSN) in experiments. Due to the broken structure inversion symmetry by the layered form in the LSN, the electron spins interact tightly with its momentums, in literatures referred to as the spin-orbit coupling (SOC) effect, which can be modulated well by the interfacial confining electric field or the stain engineering. These significant SOC effects can effectively eliminate the spin degeneracy of the electrons in semiconductor materials, induce the spin splitting phenomenon at the zero magnetic field and generate the electron-spin polarization in the semiconductors. In recent years, the spin-polarized transport for electrons in the LSN has attracted a lot of research interests, thanks to itself scientific importance and potential applications as spin polarized sources in the research field of semiconductor spintronics. Adopting the theoretical analysis combined with the numerical calculation, we investigate the spin-polarized transport induced by the Rashba-type SOC effect for electrons in a single-layered semiconductor nanostructure (SLSN)-InSb. The research objective is to explore the new way for generating and manipulating spin current in semiconductor materials without any magnetic field, and focus on developing new electron-spin filter for semiconductor spintronics device applications. The improved transfer matrix method (ITMM) is exploited to exactly solve Schrödinger equation for an electron in the SLSN-InSb device, which allows us to calculate the spin-dependent transmission coefficient and the spin polarization ratio. Due to a strong Rashba-type SOC, a considerable electron-spin polarization effect appears in the SLSN-InSb device. Because of the effective potential experienced by the electrons in the SLSN-InSb device, the spin polarization ratio is associated with the electron energy and the in-plane wave vector. In particular, the spin polarization ratio can be manipulated effectively by an externally-applied electric field or the semiconductor-layer thickness, owing to the dependence of the effective potential felt by the electrons in the SLSN-InSb device on the electric field or the layer thickness. Therefore, such a SLSN-InSb device can serve as a controllable electron-spin filter as a manipulable spin-polarized source for the research area of semiconductor spintronics.
{"title":"Electron-spin polarization effect in Rashba spin-orbit coupling modulated single-layered semiconductor nanostructure","authors":"He Ya-Ping, Chen Ming-Xia, Pan Jie-Feng, Li Dong, Lin Gang-Jun, Huang Xin-Hong","doi":"10.7498/aps.72.20221381","DOIUrl":"https://doi.org/10.7498/aps.72.20221381","url":null,"abstract":"Nanothick semiconductors can grow orderly along a desired direction with the help of modern materials growth technology such as molecular beam epitaxy, which allows researchers to fabricate the so-called layered semiconductor nanostructure (LSN) in experiments. Due to the broken structure inversion symmetry by the layered form in the LSN, the electron spins interact tightly with its momentums, in literatures referred to as the spin-orbit coupling (SOC) effect, which can be modulated well by the interfacial confining electric field or the stain engineering. These significant SOC effects can effectively eliminate the spin degeneracy of the electrons in semiconductor materials, induce the spin splitting phenomenon at the zero magnetic field and generate the electron-spin polarization in the semiconductors. In recent years, the spin-polarized transport for electrons in the LSN has attracted a lot of research interests, thanks to itself scientific importance and potential applications as spin polarized sources in the research field of semiconductor spintronics. Adopting the theoretical analysis combined with the numerical calculation, we investigate the spin-polarized transport induced by the Rashba-type SOC effect for electrons in a single-layered semiconductor nanostructure (SLSN)-InSb. The research objective is to explore the new way for generating and manipulating spin current in semiconductor materials without any magnetic field, and focus on developing new electron-spin filter for semiconductor spintronics device applications. The improved transfer matrix method (ITMM) is exploited to exactly solve Schrödinger equation for an electron in the SLSN-InSb device, which allows us to calculate the spin-dependent transmission coefficient and the spin polarization ratio. Due to a strong Rashba-type SOC, a considerable electron-spin polarization effect appears in the SLSN-InSb device. Because of the effective potential experienced by the electrons in the SLSN-InSb device, the spin polarization ratio is associated with the electron energy and the in-plane wave vector. In particular, the spin polarization ratio can be manipulated effectively by an externally-applied electric field or the semiconductor-layer thickness, owing to the dependence of the effective potential felt by the electrons in the SLSN-InSb device on the electric field or the layer thickness. Therefore, such a SLSN-InSb device can serve as a controllable electron-spin filter as a manipulable spin-polarized source for the research area of semiconductor spintronics.","PeriodicalId":6995,"journal":{"name":"Acta Physica Sinica","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77895580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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