Pub Date : 2024-07-24DOI: 10.1088/1361-6463/ad66dd
Haiwen Liu, Sidong Wang, Mingli Sun, Zeren Song, H. Tian
In this paper, a compact quad-channel filtering diplexer using meander hairpin ring resonators (M-HRR) aided by grey wolf algorithm (GWA) is proposed. To realize a compact size of the multi-channel diplexer, the form of a meander-line structure is applied to the hairpin ring resonator for the miniaturization of the proposed quad-channel diplexer. Then, using the coupling topology of the 0° feeding structure, a transmission zero (TZ) is generated between two resonant frequencies of M-HRR to improve the band-edge selectivity and band-to-band isolation of the diplexer. To address the problematic challenge of the complexity in designing the multi-channel diplexer with a time-consuming optimization manually, an intelligent GWA is utilized to optimize the physical layout of the designed circuit to achieve the desired performance of the diplexer rapidly. Furthermore, different kinds of intelligent algorithms are implemented and compared under identical conditions. Finally, a quad-channel filtering diplexer centering at 3.28/3.75/4.32/4.75 GHz with 3-dB fractional bandwidth (FBW) of 5.4%, 2.9%, 4.9%, and 3.2% respectively is fabricated and measured. The circuit occupies a compact size of 0.22λg × 0.20λg. Good accordance is observed between the simulated and measured frequency responses.
{"title":"Compact quad-channel filtering diplexer using meander hairpin ring resonator aided by grey wolf algorithm","authors":"Haiwen Liu, Sidong Wang, Mingli Sun, Zeren Song, H. Tian","doi":"10.1088/1361-6463/ad66dd","DOIUrl":"https://doi.org/10.1088/1361-6463/ad66dd","url":null,"abstract":"\u0000 In this paper, a compact quad-channel filtering diplexer using meander hairpin ring resonators (M-HRR) aided by grey wolf algorithm (GWA) is proposed. To realize a compact size of the multi-channel diplexer, the form of a meander-line structure is applied to the hairpin ring resonator for the miniaturization of the proposed quad-channel diplexer. Then, using the coupling topology of the 0° feeding structure, a transmission zero (TZ) is generated between two resonant frequencies of M-HRR to improve the band-edge selectivity and band-to-band isolation of the diplexer. To address the problematic challenge of the complexity in designing the multi-channel diplexer with a time-consuming optimization manually, an intelligent GWA is utilized to optimize the physical layout of the designed circuit to achieve the desired performance of the diplexer rapidly. Furthermore, different kinds of intelligent algorithms are implemented and compared under identical conditions. Finally, a quad-channel filtering diplexer centering at 3.28/3.75/4.32/4.75 GHz with 3-dB fractional bandwidth (FBW) of 5.4%, 2.9%, 4.9%, and 3.2% respectively is fabricated and measured. The circuit occupies a compact size of 0.22λg × 0.20λg. Good accordance is observed between the simulated and measured frequency responses.","PeriodicalId":507822,"journal":{"name":"Journal of Physics D: Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141808279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The carrier recombination behaviour of GaN-based blue laser diodes (LDs) is studied and analysed by experiments and simulation calculation before lasing, especially the role of Auger recombination. It is found that Auger recombination plays a crucial role on the decrease of differential efficiency and threshold current of GaN-based blue LDs. The theoretical calculation results show that a large Auger recombination rate may lead to a dominant recombination channel before lasing, which could exceed the radiation recombination and result in an obvious decrease of the differential efficiency. Such a high Auger recombination will dissipate a large number of carriers in the quantum well, resulting in deterioration of device performance, a higher threshold current and a lower efficiency. This work presents a method to evaluate the Auger recombination through the differential efficiency, and also give a clue that suppressing auger recombination rate is beneficial to improve the performance of blue LDs.
{"title":"Investigation on the mechanism of carrier recombination in the GaN-based blue laser diode before lasing","authors":"F. Liang, Huang Yujie, Jing Yang, Ping Chen, Zongshun Liu, Degang Zhao","doi":"10.1088/1361-6463/ad66de","DOIUrl":"https://doi.org/10.1088/1361-6463/ad66de","url":null,"abstract":"\u0000 The carrier recombination behaviour of GaN-based blue laser diodes (LDs) is studied and analysed by experiments and simulation calculation before lasing, especially the role of Auger recombination. It is found that Auger recombination plays a crucial role on the decrease of differential efficiency and threshold current of GaN-based blue LDs. The theoretical calculation results show that a large Auger recombination rate may lead to a dominant recombination channel before lasing, which could exceed the radiation recombination and result in an obvious decrease of the differential efficiency. Such a high Auger recombination will dissipate a large number of carriers in the quantum well, resulting in deterioration of device performance, a higher threshold current and a lower efficiency. This work presents a method to evaluate the Auger recombination through the differential efficiency, and also give a clue that suppressing auger recombination rate is beneficial to improve the performance of blue LDs.","PeriodicalId":507822,"journal":{"name":"Journal of Physics D: Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141806739","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-24DOI: 10.1088/1361-6463/ad66e0
Linfeng He, Xin Zhang, Xinyao Chen, Jin Cheng, Zhenjun Li, Junming Li
Tin-based perovskite has been considered as one of the most potential candidates for the lead-based perovskite. The solution proceed method were widely utilized in fabricating tin perovskite solar cells. So far, all fabrication process for tin perovskite solar cells involved the toxic organic solvents, which is contrary to the development of environmentally friendly perovskite solar cells. In this study, we report for the first time, by using a mixed green solvent N-diethyl formamide and green 1,3-Dimethyl-3,4,5,6-Tetrahydro-2 (1H)-pyrimidinone as precursor solvent, and a green solvent dibutyl ether as antisolvent, a high-quality FA0.75MA0.25SnI3 film was achieved. The optical band gap of the prepared perovskite layer was 1.36 eV, which was close to the ideal band gap. The green-solution-proceed perovskite films showed reduced defect density. As a consequence, the champion green-solution-proceed photovoltaic device achieved a power conversion efficiency of 4.4%. Moreover, it still maintains 80% of the initial efficiency after 600 hours storage in a nitrogen atmosphere. This work would promote the perovskite solar cells from a “new” technique to the “new and green” technique.
{"title":"Green-Solvent-Processed Lead-free Perovskite Solar Cells","authors":"Linfeng He, Xin Zhang, Xinyao Chen, Jin Cheng, Zhenjun Li, Junming Li","doi":"10.1088/1361-6463/ad66e0","DOIUrl":"https://doi.org/10.1088/1361-6463/ad66e0","url":null,"abstract":"\u0000 Tin-based perovskite has been considered as one of the most potential candidates for the lead-based perovskite. The solution proceed method were widely utilized in fabricating tin perovskite solar cells. So far, all fabrication process for tin perovskite solar cells involved the toxic organic solvents, which is contrary to the development of environmentally friendly perovskite solar cells. In this study, we report for the first time, by using a mixed green solvent N-diethyl formamide and green 1,3-Dimethyl-3,4,5,6-Tetrahydro-2 (1H)-pyrimidinone as precursor solvent, and a green solvent dibutyl ether as antisolvent, a high-quality FA0.75MA0.25SnI3 film was achieved. The optical band gap of the prepared perovskite layer was 1.36 eV, which was close to the ideal band gap. The green-solution-proceed perovskite films showed reduced defect density. As a consequence, the champion green-solution-proceed photovoltaic device achieved a power conversion efficiency of 4.4%. Moreover, it still maintains 80% of the initial efficiency after 600 hours storage in a nitrogen atmosphere. This work would promote the perovskite solar cells from a “new” technique to the “new and green” technique.","PeriodicalId":507822,"journal":{"name":"Journal of Physics D: Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141808542","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-24DOI: 10.1088/1361-6463/ad66df
H. Muneoka, Takeru Koike, Tsuyohito Ito, Kazuo Terashima, Eisuke Miura
This study investigates the particle-size reduction of hexagonal boron nitride (hBN) suspensions under femtosecond-laser irradiation. We propose an in-line monitoring method that uses transmission spectroscopy (TS) in the visible wavelength region to evaluate the changes in particle-size distribution. The Ångström exponent (α), derived from the wavelength dependence of optical thickness, is employed as an indicator of particle-size reduction. The effectiveness of α is validated through comparison with particle-size distributions obtained by the particle tracking method. We demonstrate real-time monitoring of particle-size variation in a flow system using in-line TS measurements. The dependence of α on laser energy and hBN concentration is also investigated. Furthermore, we introduce an indicator, the average number of size-reduction events per particle (NSR), and a model for estimating it under various experimental conditions. The NSR indicator and the model for its derivation provide a unified understanding of the experimental results obtained under various conditions, such as treatment volume, laser energy, and hBN concentration, suggesting that they capture the essential aspects of laser propagation in the suspension and the particle-size reduction process. This study highlights the potential of α as an in-line process monitoring tool and the significance of the NSR indicator and its model in understanding the underlying mechanisms of laser processing for particle-size reduction in suspensions.
{"title":"In-line monitoring and modelling of particle size reduction of hexagonal boron nitride (hBN) suspension in femtosecond laser processing","authors":"H. Muneoka, Takeru Koike, Tsuyohito Ito, Kazuo Terashima, Eisuke Miura","doi":"10.1088/1361-6463/ad66df","DOIUrl":"https://doi.org/10.1088/1361-6463/ad66df","url":null,"abstract":"\u0000 This study investigates the particle-size reduction of hexagonal boron nitride (hBN) suspensions under femtosecond-laser irradiation. We propose an in-line monitoring method that uses transmission spectroscopy (TS) in the visible wavelength region to evaluate the changes in particle-size distribution. The Ångström exponent (α), derived from the wavelength dependence of optical thickness, is employed as an indicator of particle-size reduction. The effectiveness of α is validated through comparison with particle-size distributions obtained by the particle tracking method. We demonstrate real-time monitoring of particle-size variation in a flow system using in-line TS measurements. The dependence of α on laser energy and hBN concentration is also investigated. Furthermore, we introduce an indicator, the average number of size-reduction events per particle (NSR), and a model for estimating it under various experimental conditions. The NSR indicator and the model for its derivation provide a unified understanding of the experimental results obtained under various conditions, such as treatment volume, laser energy, and hBN concentration, suggesting that they capture the essential aspects of laser propagation in the suspension and the particle-size reduction process. This study highlights the potential of α as an in-line process monitoring tool and the significance of the NSR indicator and its model in understanding the underlying mechanisms of laser processing for particle-size reduction in suspensions.","PeriodicalId":507822,"journal":{"name":"Journal of Physics D: Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141807571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-23DOI: 10.1088/1361-6463/ad6671
Miao Zhang, Zixin Peng
Supercapacitors have become attractive energy storage devices due to their high power density, good cycling stability, and fast charging and discharging speeds. Porous carbon has great specific surface area, high energy density and good conversion performance, so porous carbon as supercapacitor electrode material has been widely concerned. Carbon materials with different dimensions and sizes, such as porous carbon spheres, porous carbon nanotubes (CNTs), porous carbon nanofibers (CNFs) porous graphene (GR) and activated carbon (AC) can provide different performance advantages. At the same time, the composite of porous carbon with metal compounds, conductive polymers and particles containing N/P/O/S can further optimize electrode materials, as well as the significant effects on the increase of specific surface area and energy density are obtained. This article introduces the porous carbon materials used as electrode materials in recent years, as well as their multi-level structural materials and related composite materials. We first introduced porous carbon electrode materials with different dimensions and compared their electrochemical performance. Then, based on various research results, the factors affecting its electrochemical performance were discussed in detail. As well as, the preparation methods of porous carbon electrode materials were introduced, and the specific requirements, advantages and disadvantages of different preparation methods were briefly analyzed. The application of porous carbon electrode materials combined with other materials in supercapacitors is listed. Finally, a summary and outlook of the current research status were supplied, providing reference for the rational design of porous carbon supercapacitors in the future.
{"title":"Porous carbon materials with different dimensions and their applications in supercapacitors","authors":"Miao Zhang, Zixin Peng","doi":"10.1088/1361-6463/ad6671","DOIUrl":"https://doi.org/10.1088/1361-6463/ad6671","url":null,"abstract":"\u0000 Supercapacitors have become attractive energy storage devices due to their high power density, good cycling stability, and fast charging and discharging speeds. Porous carbon has great specific surface area, high energy density and good conversion performance, so porous carbon as supercapacitor electrode material has been widely concerned. Carbon materials with different dimensions and sizes, such as porous carbon spheres, porous carbon nanotubes (CNTs), porous carbon nanofibers (CNFs) porous graphene (GR) and activated carbon (AC) can provide different performance advantages. At the same time, the composite of porous carbon with metal compounds, conductive polymers and particles containing N/P/O/S can further optimize electrode materials, as well as the significant effects on the increase of specific surface area and energy density are obtained. This article introduces the porous carbon materials used as electrode materials in recent years, as well as their multi-level structural materials and related composite materials. We first introduced porous carbon electrode materials with different dimensions and compared their electrochemical performance. Then, based on various research results, the factors affecting its electrochemical performance were discussed in detail. As well as, the preparation methods of porous carbon electrode materials were introduced, and the specific requirements, advantages and disadvantages of different preparation methods were briefly analyzed. The application of porous carbon electrode materials combined with other materials in supercapacitors is listed. Finally, a summary and outlook of the current research status were supplied, providing reference for the rational design of porous carbon supercapacitors in the future.","PeriodicalId":507822,"journal":{"name":"Journal of Physics D: Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141813737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-23DOI: 10.1088/1361-6463/ad6672
jialong li, Xinhui Zhu, Yuxuan Sun, Q. Cao, Liang Li
Uniform magnetic field coils are widely used as electromagnetic equipment in industrial, medical, and research applications, with Helmholtz coils being a common configuration among them. For applications requiring relatively high magnetic field (~mT), Helmholtz coils typically feature a large coil cross-section. However, this characteristic makes them unsuitable for describing the magnetic field generated by a current loop model in the design process. In this work, we model the magnetic field of a large cross-section Helmholtz coil system, often referred to as a thick-walled Helmholtz coil. By employing a genetic algorithm, we transform the design problem of Helmholtz coil into a constrained optimization problem. Subsequently, we propose a method for reverse designing a Helmholtz coil based on constraints on the target magnetic field. Finite element simulations verify the accuracy of the established magnetic field calculation model in describing the magnetic field generated by the thick-walled Helmholtz coil. Moreover, the designed Helmholtz coil effectively meets the design constraints and objectives. This method addresses the issue of significant errors in calculating the magnetic field and its uniformity resulting from the cross-section effect during the design of thick-walled Helmholtz coils. Furthermore, it satisfies the constraints for coil operating time and lightweight design.
{"title":"Optimal design of thick-walled circular coils for uniform magnetic field generation","authors":"jialong li, Xinhui Zhu, Yuxuan Sun, Q. Cao, Liang Li","doi":"10.1088/1361-6463/ad6672","DOIUrl":"https://doi.org/10.1088/1361-6463/ad6672","url":null,"abstract":"\u0000 Uniform magnetic field coils are widely used as electromagnetic equipment in industrial, medical, and research applications, with Helmholtz coils being a common configuration among them. For applications requiring relatively high magnetic field (~mT), Helmholtz coils typically feature a large coil cross-section. However, this characteristic makes them unsuitable for describing the magnetic field generated by a current loop model in the design process. In this work, we model the magnetic field of a large cross-section Helmholtz coil system, often referred to as a thick-walled Helmholtz coil. By employing a genetic algorithm, we transform the design problem of Helmholtz coil into a constrained optimization problem. Subsequently, we propose a method for reverse designing a Helmholtz coil based on constraints on the target magnetic field. Finite element simulations verify the accuracy of the established magnetic field calculation model in describing the magnetic field generated by the thick-walled Helmholtz coil. Moreover, the designed Helmholtz coil effectively meets the design constraints and objectives. This method addresses the issue of significant errors in calculating the magnetic field and its uniformity resulting from the cross-section effect during the design of thick-walled Helmholtz coils. Furthermore, it satisfies the constraints for coil operating time and lightweight design.","PeriodicalId":507822,"journal":{"name":"Journal of Physics D: Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141812910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-23DOI: 10.1088/1361-6463/ad6674
Ke Chen, B. Du, Haoliang Liu, M. Xiao
In this paper, maleic anhydride (MAH) was grafted on the surfaces of biaxially oriented polypropylene (BOPP) film by ultraviolet irradiation treatment to improve the breakdown strength. The addition of MAH, with abundant deep traps, effectively hinders charge injection from the electrode, leading to improved dielectric performance, particularly at elevated temperatures. The experimental results show that the received modified film exhibits an improved permittivity of 2.37 alongside a low dielectric loss of 0.0022 at 1000Hz. Remarkably, the DC breakdown strength reaches 633.9 kV/mm, marking a notable 21.4% increase compared to the unmodified BOPP film at 120 °C. Moreover, the film exhibits an energy density of 2.58 J/m³, which is 1.59 times that of the pure film. The charging and discharging efficiency is also greatly improved due to the reduction of conductance losses . Through simulation results, it becomes evident that the enhanced performance is attributed to the alleviation of electric field distortion due to the suppression of injected charge. This work paves a facile route to design scalable polymeric dielectrics with outstanding performance, which facilitates the development of film capacitors.
本文通过紫外线辐照处理在双向拉伸聚丙烯（BOPP）薄膜表面接枝马来酸酐（MAH），以提高击穿强度。添加的 MAH 具有丰富的深阱，可有效阻止电荷从电极注入，从而改善介电性能，尤其是在高温条件下。实验结果表明，经过改性的薄膜在 1000Hz 频率下的介电损耗低至 0.0022，介电系数提高到 2.37。值得注意的是，在 120 °C 时，直流击穿强度达到 633.9 kV/mm，与未改性的 BOPP 薄膜相比显著提高了 21.4%。此外，薄膜的能量密度为 2.58 J/m³，是纯薄膜的 1.59 倍。由于减少了电导损耗，充放电效率也大大提高。模拟结果表明，性能的提高归因于注入电荷的抑制减轻了电场畸变。这项研究为设计性能卓越的可扩展聚合物电介质铺平了道路，促进了薄膜电容器的发展。
{"title":"Enhanced Energy Density of BOPP Film by MAH Grafting for Metallized Capacitors","authors":"Ke Chen, B. Du, Haoliang Liu, M. Xiao","doi":"10.1088/1361-6463/ad6674","DOIUrl":"https://doi.org/10.1088/1361-6463/ad6674","url":null,"abstract":"\u0000 In this paper, maleic anhydride (MAH) was grafted on the surfaces of biaxially oriented polypropylene (BOPP) film by ultraviolet irradiation treatment to improve the breakdown strength. The addition of MAH, with abundant deep traps, effectively hinders charge injection from the electrode, leading to improved dielectric performance, particularly at elevated temperatures. The experimental results show that the received modified film exhibits an improved permittivity of 2.37 alongside a low dielectric loss of 0.0022 at 1000Hz. Remarkably, the DC breakdown strength reaches 633.9 kV/mm, marking a notable 21.4% increase compared to the unmodified BOPP film at 120 °C. Moreover, the film exhibits an energy density of 2.58 J/m³, which is 1.59 times that of the pure film. The charging and discharging efficiency is also greatly improved due to the reduction of conductance losses . Through simulation results, it becomes evident that the enhanced performance is attributed to the alleviation of electric field distortion due to the suppression of injected charge. This work paves a facile route to design scalable polymeric dielectrics with outstanding performance, which facilitates the development of film capacitors.","PeriodicalId":507822,"journal":{"name":"Journal of Physics D: Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141810618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-23DOI: 10.1088/1361-6463/ad6673
Aman Sharma, Debabrata Goswami
In this study, we comprehensively investigate Thermal lens (TL) spectroscopy, known for its ultra-sensitivity in probing molecular properties through nonlinear heating responses to femtosecond lasers. Using time-resolved TL spectroscopy and numerical simulations, we focus on the influence of convection on heat generation and the resulting phase shift in the probe beam. We examined single-beam, dual-beam same wavelength, and dual-beam different wavelength scenarios, systematically investigating power dependence, pump beam spot size, and sample length limitations. Our findings reveal a direct relationship between the TL effect and pump power, resulting in decreased probe beam transmittance with increasing convection. Additionally, the thermal lens strength grows within the Rayleigh regime as the sample length increases. Utilizing the same wavelength for the probe beam enhances the thermal lens effect in dual-beam setups. Notably, tight focusing of the pump beam substantially reduces the lag between convection and conduction. Our empirical results closely match the experimental data, providing a thorough explanation of the TL process and its underlying principles. These insights can be applied to design and optimize TL-based optical devices and systems for higher sensitivity, highlighting the potential of TL spectroscopy in advanced molecular property probing.
{"title":"Impact of molecular convection in time-resolved thermal lensing: a computational exploration","authors":"Aman Sharma, Debabrata Goswami","doi":"10.1088/1361-6463/ad6673","DOIUrl":"https://doi.org/10.1088/1361-6463/ad6673","url":null,"abstract":"\u0000 In this study, we comprehensively investigate Thermal lens (TL) spectroscopy, known for its ultra-sensitivity in probing molecular properties through nonlinear heating responses to femtosecond lasers. Using time-resolved TL spectroscopy and numerical simulations, we focus on the influence of convection on heat generation and the resulting phase shift in the probe beam. We examined single-beam, dual-beam same wavelength, and dual-beam different wavelength scenarios, systematically investigating power dependence, pump beam spot size, and sample length limitations. Our findings reveal a direct relationship between the TL effect and pump power, resulting in decreased probe beam transmittance with increasing convection. Additionally, the thermal lens strength grows within the Rayleigh regime as the sample length increases. Utilizing the same wavelength for the probe beam enhances the thermal lens effect in dual-beam setups. Notably, tight focusing of the pump beam substantially reduces the lag between convection and conduction. Our empirical results closely match the experimental data, providing a thorough explanation of the TL process and its underlying principles. These insights can be applied to design and optimize TL-based optical devices and systems for higher sensitivity, highlighting the potential of TL spectroscopy in advanced molecular property probing.","PeriodicalId":507822,"journal":{"name":"Journal of Physics D: Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141812781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The negative capacitance field-effect transistor with 2D channel material (2D NC-FET) holds significant promise for low-power applications owing to its remarkable resilience against short-channel effects (SCEs) and favorable noise characteristics. In this study, we establish a compact current-voltage (I-V) model for short-channel back-gated 2D NC-FETs with metal-ferroelectric-metal-insulator-semiconductor (MFMIS) structure by self-consistently solving the two-dimensional Poisson, drift-diffusion and Landau-Khalatnikov equations. The proposed model is valid and continuous throughout the entire operating regime, including the fully-depleted region, partly-depleted region, and accumulation region. Furthermore, we derive analytical equations for the threshold voltage (V_TH) and subthreshold swing (SS) of back-gated 2D NC-FETs based on the developed I-V model. Lastly, we elucidate the influence mechanisms of various device parameters and voltage bias on the subthreshold characteristics of short-channel back-gated 2D NC-FETs using the proposed I-V model in conjunction with analytical expressions of V_TH and SS. Our findings reveal that back-gated 2D NC-FETs shows unconventional degradation behavior in V_TH and SS, resulting from the competition between traditional short-channel effects (SCEs) and novel negative capacitance (NC) effects.
{"title":"Compact modeling of short-channel effects in back-gated 2D Negative Capacitance (NC) FETs","authors":"Chunsheng Jiang, Qing Lu, Liyang Pan, Quanfu Li, Hui-Ling Peng, Zhigang Zhang, Shuxiang Song, Jun Xu","doi":"10.1088/1361-6463/ad6611","DOIUrl":"https://doi.org/10.1088/1361-6463/ad6611","url":null,"abstract":"\u0000 The negative capacitance field-effect transistor with 2D channel material (2D NC-FET) holds significant promise for low-power applications owing to its remarkable resilience against short-channel effects (SCEs) and favorable noise characteristics. In this study, we establish a compact current-voltage (I-V) model for short-channel back-gated 2D NC-FETs with metal-ferroelectric-metal-insulator-semiconductor (MFMIS) structure by self-consistently solving the two-dimensional Poisson, drift-diffusion and Landau-Khalatnikov equations. The proposed model is valid and continuous throughout the entire operating regime, including the fully-depleted region, partly-depleted region, and accumulation region. Furthermore, we derive analytical equations for the threshold voltage (V_TH) and subthreshold swing (SS) of back-gated 2D NC-FETs based on the developed I-V model. Lastly, we elucidate the influence mechanisms of various device parameters and voltage bias on the subthreshold characteristics of short-channel back-gated 2D NC-FETs using the proposed I-V model in conjunction with analytical expressions of V_TH and SS. Our findings reveal that back-gated 2D NC-FETs shows unconventional degradation behavior in V_TH and SS, resulting from the competition between traditional short-channel effects (SCEs) and novel negative capacitance (NC) effects.","PeriodicalId":507822,"journal":{"name":"Journal of Physics D: Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141816181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-22DOI: 10.1088/1361-6463/ad6612
Yaning Xu, Ximin Tian, junwei xu, Shenglan Zhang, Yafeng Huang, Liang Li, Jielong Liu, Kun Xu, Zhanjun Yu, Zhiyuan Li
Optical trapping, a cutting-edge methodology, is pivotal for contactlessly controlling and exploring microscopic objects. However, it encounters formidable challenges such as multiparticle trapping, flexible control, and seamless integration. Here, we employ a polarization-modulated multi-foci technique for versatile nanoparticle trapping using multifunctional metasurfaces relying on geometric phase. Numerical simulations demonstrate the generation of two focused spots with orthogonal polarization distributions through our metasurfaces when illuminated with linearly polarized light, with their polarization distributions be interchanged by orthogonally switching the incident polarizations. We extend this design to an array of multi-foci metasurface tweezers modulated by polarization, highlighting the versatility and robustness of our approach. Furthermore, we demonstrate the simultaneous generation of two distinct focusing cylindrical vector beams using a monolayer metasurface, showcasing the two vector beams possess the interchange ability of their polarization distributions. By leveraging the Maxwell stress tensor, we assess the distinct contributions of the focused beams to longitudinal and transverse optical forces on SiO2 spheres, validating diverse trapping and manipulation behaviors for nanoparticles with the proposed metasurface designs. By manipulating the phase states of Sb2S3 nanopillars, binary-switchable optical trapping and manipulation are facilitated for for all proposed metasurface tweezers. Our work underscores the efficacy of polarization-modulation multifunctional metasurface tweezers in consolidating multiple trapping tasks into a single device, paving the way for innovative lab-on-a-chip optical trapping applications in biophysics, nanotechnology, and photonics.
{"title":"Switchable optical trapping and manipulation enabled by polarization-modulated multifunctional phase-change metasurfaces","authors":"Yaning Xu, Ximin Tian, junwei xu, Shenglan Zhang, Yafeng Huang, Liang Li, Jielong Liu, Kun Xu, Zhanjun Yu, Zhiyuan Li","doi":"10.1088/1361-6463/ad6612","DOIUrl":"https://doi.org/10.1088/1361-6463/ad6612","url":null,"abstract":"\u0000 Optical trapping, a cutting-edge methodology, is pivotal for contactlessly controlling and exploring microscopic objects. However, it encounters formidable challenges such as multiparticle trapping, flexible control, and seamless integration. Here, we employ a polarization-modulated multi-foci technique for versatile nanoparticle trapping using multifunctional metasurfaces relying on geometric phase. Numerical simulations demonstrate the generation of two focused spots with orthogonal polarization distributions through our metasurfaces when illuminated with linearly polarized light, with their polarization distributions be interchanged by orthogonally switching the incident polarizations. We extend this design to an array of multi-foci metasurface tweezers modulated by polarization, highlighting the versatility and robustness of our approach. Furthermore, we demonstrate the simultaneous generation of two distinct focusing cylindrical vector beams using a monolayer metasurface, showcasing the two vector beams possess the interchange ability of their polarization distributions. By leveraging the Maxwell stress tensor, we assess the distinct contributions of the focused beams to longitudinal and transverse optical forces on SiO2 spheres, validating diverse trapping and manipulation behaviors for nanoparticles with the proposed metasurface designs. By manipulating the phase states of Sb2S3 nanopillars, binary-switchable optical trapping and manipulation are facilitated for for all proposed metasurface tweezers. Our work underscores the efficacy of polarization-modulation multifunctional metasurface tweezers in consolidating multiple trapping tasks into a single device, paving the way for innovative lab-on-a-chip optical trapping applications in biophysics, nanotechnology, and photonics.","PeriodicalId":507822,"journal":{"name":"Journal of Physics D: Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141815278","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：