K. Keller, R. Rojas-Aedo, Huiqin Zhang, P. Schweizer, J. Allerbeck, D. Brida, D. Jariwala, N. Maccaferri
Interface effects in metals-semiconductors heterojunctions are subject of intense research due to the possibility to exploit the synergy between their electronic and optical properties in next-generation opto-electronic devices. In this framework, understanding the carrier dynamics at the metal-semiconductor interface, as well as achieving a coherent control of charge and energy transfer in metal-semiconductor heterostructures, are crucial and yet quite unexplored aspects. Here, we experimentally show that thermionically injected carriers from a gold substrate can drastically affect the dynamics of excited carriers in bulk WS2. By employing a pump-push-probe scheme, where a push pulse excites direct transitions in the WS2, and another delayed pump pulse induces thermionic injection of carriers from the gold substrate into the semiconductor, we can control both the formation and annihilation of excitons. Our findings might foster the development of novel opto-electronic approaches to control charge dynamics using light at ultrafast timescales.
{"title":"Ultrafast control of exciton dynamics by optically-induced thermionic carrier injection in a metal-semiconductor heterojunction","authors":"K. Keller, R. Rojas-Aedo, Huiqin Zhang, P. Schweizer, J. Allerbeck, D. Brida, D. Jariwala, N. Maccaferri","doi":"10.1117/12.2665677","DOIUrl":"https://doi.org/10.1117/12.2665677","url":null,"abstract":"Interface effects in metals-semiconductors heterojunctions are subject of intense research due to the possibility to exploit the synergy between their electronic and optical properties in next-generation opto-electronic devices. In this framework, understanding the carrier dynamics at the metal-semiconductor interface, as well as achieving a coherent control of charge and energy transfer in metal-semiconductor heterostructures, are crucial and yet quite unexplored aspects. Here, we experimentally show that thermionically injected carriers from a gold substrate can drastically affect the dynamics of excited carriers in bulk WS2. By employing a pump-push-probe scheme, where a push pulse excites direct transitions in the WS2, and another delayed pump pulse induces thermionic injection of carriers from the gold substrate into the semiconductor, we can control both the formation and annihilation of excitons. Our findings might foster the development of novel opto-electronic approaches to control charge dynamics using light at ultrafast timescales.","PeriodicalId":376481,"journal":{"name":"Optics + Optoelectronics","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129822561","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}
Table-top beamlines based on high-order laser harmonics (HHs) are nowadays lab-based facilities commonly used both for ultrafast experiments on its own sake and in preparatory experiments conceived, ab initio, for large-scale facilities such as FELs. Differently from FELs, HHs are emitted in a broad spectral range, requiring for most experiments the selection of a single harmonic. The monochromatization should preserve the temporal structure of the femtosecond pulse in a so-called time-delay-compensated monochromator (TDCM), where a couple of gratings is used in a configuration to compensate for the pulse-front tilt. At present, TDCMs in the extreme ultraviolet (15–100 eV) are realized using six optics at grazing incidence: two plane gratings and four toroidal mirrors. The gratings are illuminated by a collimated beam and the mirrors are used to collimate and focus the beam in the two sections of the monochromator: intermediate slit and target area. Here we present the design of a TDCM with four optical elements: two gratings, a cylindrical(spherical) mirror and a toroidal mirror. The gratings are used in the off-plane geometry and are illuminated by a divergent beam. The optical design is discussed in detail giving all the parameters for the definition of the configuration. We present the design of a TDCM for the 15-60 eV region, being a physical realization in progress. The main topics discussed are the beam size at the target area, the residual temporal broadening, the error budget for the alignment and the expected throughput. The design has advantages in terms of costs, compactness, alignment stability and throughput.
{"title":"Design of a compact time-delay-compensated monochromator for femtosecond pulses in the extreme-ultraviolet","authors":"F. Frassetto, L. Poletto","doi":"10.1117/12.2665826","DOIUrl":"https://doi.org/10.1117/12.2665826","url":null,"abstract":"Table-top beamlines based on high-order laser harmonics (HHs) are nowadays lab-based facilities commonly used both for ultrafast experiments on its own sake and in preparatory experiments conceived, ab initio, for large-scale facilities such as FELs. Differently from FELs, HHs are emitted in a broad spectral range, requiring for most experiments the selection of a single harmonic. The monochromatization should preserve the temporal structure of the femtosecond pulse in a so-called time-delay-compensated monochromator (TDCM), where a couple of gratings is used in a configuration to compensate for the pulse-front tilt. At present, TDCMs in the extreme ultraviolet (15–100 eV) are realized using six optics at grazing incidence: two plane gratings and four toroidal mirrors. The gratings are illuminated by a collimated beam and the mirrors are used to collimate and focus the beam in the two sections of the monochromator: intermediate slit and target area. Here we present the design of a TDCM with four optical elements: two gratings, a cylindrical(spherical) mirror and a toroidal mirror. The gratings are used in the off-plane geometry and are illuminated by a divergent beam. The optical design is discussed in detail giving all the parameters for the definition of the configuration. We present the design of a TDCM for the 15-60 eV region, being a physical realization in progress. The main topics discussed are the beam size at the target area, the residual temporal broadening, the error budget for the alignment and the expected throughput. The design has advantages in terms of costs, compactness, alignment stability and throughput.","PeriodicalId":376481,"journal":{"name":"Optics + Optoelectronics","volume":"111 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130740077","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}
Electron acceleration by laser pulses with high repetition rate can be used for technical applications. To reach conditions for the wake-field laser acceleration, it was demonstrated recently in experiments that it is beneficial to use near single cycle laser drive pulses with sub-4 fs duration, with narrow waists. To explore possible electron density ramp-up injection as an alternative to ramp-down and ionization injections, we performed numerical simulations of electron bunches generation in the ramp-up region. The PIC code Epoch2D and input parameters near to experiments were used. We assumed thin plasma slabs with super Gaussian density profiles of order 4-80, FWHM about 30 µm. We found that density ramp-up injected bunches can have charges several times higher than those obtained by ionization injection. There can be created a group of up to ten bunches in a sequence of bubbles, with not too mutually different maximum energy and charges. At oblique incidence of drive pulses on steep ramp up profiles, we find significant enhancement of the first bunch charge. For large slant angles -45 or 45 degrees, the bunch charge enhancement is about twenty times. We conclude that the ramp-up injection can be a useful alternative injection on steep enough density profiles.
{"title":"Electron injection on steep ramp-up plasma density profiles in high repetition rate laser-plasma wake-field accelerators","authors":"V. Petržílka, P. Gajdos, M. Krus","doi":"10.1117/12.2660115","DOIUrl":"https://doi.org/10.1117/12.2660115","url":null,"abstract":"Electron acceleration by laser pulses with high repetition rate can be used for technical applications. To reach conditions for the wake-field laser acceleration, it was demonstrated recently in experiments that it is beneficial to use near single cycle laser drive pulses with sub-4 fs duration, with narrow waists. To explore possible electron density ramp-up injection as an alternative to ramp-down and ionization injections, we performed numerical simulations of electron bunches generation in the ramp-up region. The PIC code Epoch2D and input parameters near to experiments were used. We assumed thin plasma slabs with super Gaussian density profiles of order 4-80, FWHM about 30 µm. We found that density ramp-up injected bunches can have charges several times higher than those obtained by ionization injection. There can be created a group of up to ten bunches in a sequence of bubbles, with not too mutually different maximum energy and charges. At oblique incidence of drive pulses on steep ramp up profiles, we find significant enhancement of the first bunch charge. For large slant angles -45 or 45 degrees, the bunch charge enhancement is about twenty times. We conclude that the ramp-up injection can be a useful alternative injection on steep enough density profiles.","PeriodicalId":376481,"journal":{"name":"Optics + Optoelectronics","volume":"312 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133241314","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}
Amalia D'Avino, D. Sagnelli, A. Vestri, M. Rippa, V. Marchesano, V. Ambrogi, Anna De Girolamo, F. Loffredo, F. Villani, G. Nenna, L. Petti
In the last decade, smart materials have been developed in the fields of optical machines, sensors, motors, robots, and energy harvesting. This is due to their capability to respond to external stimuli or environmental changes. Among smart materials, photo-mobile polymers (PMPs) based on liquid crystals are the most promising in the field of photo-responsive actuators. These polymers are made with a mixture of liquid crystals containing azobenzene moieties that can undergo photoisomerization from trans to cis under UV light. This process leads to a macroscopic bending of the PMPs, which transforms light into mechanical energy. To enhance the PMPs' actuation, a novel liquid crystal nanocomposite is proposed. In our work, the nanocomposites are prepared with different concentrations of ZnO nanoparticles (NPs) embedded in the cross-linked polymer matrix. We have demonstrated that ZnO NPs improve the actuation and mechanical properties of the PMP, and the main aim of this assay is to optimize such effect as a function of the nanoparticles concentration. We also show the lowest and highest amounts of ZnO needed to enhance the bending behavior of the PMP. Optical, mechanical, and thermal analyses were performed to characterize the PMPs. Spectral characterization in UV/vis range of the bare and doped films, optical and atomic force microscopy, were used to comprehend the role of ZnO nanoparticles and their distribution among the liquid crystals. To study the dynamic response of the PMPs and their mechanical properties, lasers at different wavelengths were used.
{"title":"Optimization of PMP films’ production and mechanical properties based on ZnO nanoparticles addition","authors":"Amalia D'Avino, D. Sagnelli, A. Vestri, M. Rippa, V. Marchesano, V. Ambrogi, Anna De Girolamo, F. Loffredo, F. Villani, G. Nenna, L. Petti","doi":"10.1117/12.2665616","DOIUrl":"https://doi.org/10.1117/12.2665616","url":null,"abstract":"In the last decade, smart materials have been developed in the fields of optical machines, sensors, motors, robots, and energy harvesting. This is due to their capability to respond to external stimuli or environmental changes. Among smart materials, photo-mobile polymers (PMPs) based on liquid crystals are the most promising in the field of photo-responsive actuators. These polymers are made with a mixture of liquid crystals containing azobenzene moieties that can undergo photoisomerization from trans to cis under UV light. This process leads to a macroscopic bending of the PMPs, which transforms light into mechanical energy. To enhance the PMPs' actuation, a novel liquid crystal nanocomposite is proposed. In our work, the nanocomposites are prepared with different concentrations of ZnO nanoparticles (NPs) embedded in the cross-linked polymer matrix. We have demonstrated that ZnO NPs improve the actuation and mechanical properties of the PMP, and the main aim of this assay is to optimize such effect as a function of the nanoparticles concentration. We also show the lowest and highest amounts of ZnO needed to enhance the bending behavior of the PMP. Optical, mechanical, and thermal analyses were performed to characterize the PMPs. Spectral characterization in UV/vis range of the bare and doped films, optical and atomic force microscopy, were used to comprehend the role of ZnO nanoparticles and their distribution among the liquid crystals. To study the dynamic response of the PMPs and their mechanical properties, lasers at different wavelengths were used.","PeriodicalId":376481,"journal":{"name":"Optics + Optoelectronics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133895210","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}
Laser wakefield acceleration is a remarkably efficient method for relativistic electron acceleration that ensures high electric field gradients generated by plasma waves. In this approach, an ultra-short, high-intensity laser pulse propagates through a plasma medium. It has already proven its potential by reaching gradients up to hundreds of GV/m. To further stabilize and control the process of acceleration, a separate source of electrons is widely considered. In order to address this problem, we have performed 3D particle-in-cell simulations using the Smilei code. Several plasma density profiles with different vacuum-plasma transition region and their effect on the external injection were analysed.
{"title":"Transition of electron beams between vacuum and plasma in the external injection into a laser wakefield accelerator","authors":"David Gregocki, Dominika Mašlárová, M. Krůs","doi":"10.1117/12.2665683","DOIUrl":"https://doi.org/10.1117/12.2665683","url":null,"abstract":"Laser wakefield acceleration is a remarkably efficient method for relativistic electron acceleration that ensures high electric field gradients generated by plasma waves. In this approach, an ultra-short, high-intensity laser pulse propagates through a plasma medium. It has already proven its potential by reaching gradients up to hundreds of GV/m. To further stabilize and control the process of acceleration, a separate source of electrons is widely considered. In order to address this problem, we have performed 3D particle-in-cell simulations using the Smilei code. Several plasma density profiles with different vacuum-plasma transition region and their effect on the external injection were analysed.","PeriodicalId":376481,"journal":{"name":"Optics + Optoelectronics","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115727202","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}
Karel Veselský, M. Jelínek, V. Kubecek, J. Šulc, H. Jelínková, Yangxiao Wang, Zhonghan Zhang, L. Su
We present a temperature influence (in range from 78 up to 300 K) on the spectroscopic and laser properties of Tm:SrF2 crystal doped with 2 at. % of Tm3+. The sample was grown using the temperature gradient technique in shape of a single-crystal fiber (d= 2 mm, l = 5 mm) with plane-parallel face-polished without any AR coating. The Tm:SrF2 crystal was mounted in a temperature-controlled copper holder of the liquid nitrogen cryostat. The measured absorption and emission spectra remained broad even at low temperature. The fluorescence lifetime was fitted with a double exponential function, and the measured lifetime changed significantly with temperature decrease. The 147 mm long semi-hemispherical laser resonator consisted of a flat pumping mirror (T < 95 % @ 763 nm, HR @ 1750-2100 nm) placed inside the cryostat and a curved output coupler (r=150 mm, R=97.5 % @ 1750-2100 nm) placed outside the cryostat. For longitudinal pumping, a fiber coupled laser diode was used. The diode was operating in the pulse regime (5 ms pulse length, 10 Hz repetition rate) at wavelength 763 nm. At room temperature, the laser emission was achieved at 1949 nm with a high 38 % slope efficiency. With a temperature decrease, the slope efficiency increased, and the laser threshold decreased, and the laser output wavelength shifted.
我们研究了温度对掺杂2at的Tm:SrF2晶体的光谱和激光特性的影响(范围从78到300 K)。% Tm3+。样品采用温度梯度法生长成单晶纤维形状(d= 2 mm, l = 5 mm)，并在无AR涂层的情况下进行平面平行表面抛光。将Tm:SrF2晶体安装在液氮低温恒温器的温控铜支架中。测得的吸收和发射光谱即使在低温下也保持宽广。荧光寿命符合双指数函数，随温度的降低，荧光寿命变化显著。147mm长的半球形激光谐振器由放置在低温恒温器内部的平面泵浦反射镜(T < 95% @ 763 nm, HR @ 1750-2100 nm)和放置在低温恒温器外部的弯曲输出耦合器(r=150 mm, r= 97.5% @ 1750-2100 nm)组成。纵向泵浦采用光纤耦合激光二极管。二极管在763 nm波长的脉冲状态下工作(5 ms脉冲长度，10 Hz重复率)。在室温下，激光发射波长为1949 nm，斜率效率高达38%。随着温度的降低，斜率效率增加，激光阈值降低，激光输出波长发生偏移。
{"title":"Effect of cryogenic temperature on spectroscopic and laser properties of Tm:SrF2 crystal","authors":"Karel Veselský, M. Jelínek, V. Kubecek, J. Šulc, H. Jelínková, Yangxiao Wang, Zhonghan Zhang, L. Su","doi":"10.1117/12.2665636","DOIUrl":"https://doi.org/10.1117/12.2665636","url":null,"abstract":"We present a temperature influence (in range from 78 up to 300 K) on the spectroscopic and laser properties of Tm:SrF2 crystal doped with 2 at. % of Tm3+. The sample was grown using the temperature gradient technique in shape of a single-crystal fiber (d= 2 mm, l = 5 mm) with plane-parallel face-polished without any AR coating. The Tm:SrF2 crystal was mounted in a temperature-controlled copper holder of the liquid nitrogen cryostat. The measured absorption and emission spectra remained broad even at low temperature. The fluorescence lifetime was fitted with a double exponential function, and the measured lifetime changed significantly with temperature decrease. The 147 mm long semi-hemispherical laser resonator consisted of a flat pumping mirror (T < 95 % @ 763 nm, HR @ 1750-2100 nm) placed inside the cryostat and a curved output coupler (r=150 mm, R=97.5 % @ 1750-2100 nm) placed outside the cryostat. For longitudinal pumping, a fiber coupled laser diode was used. The diode was operating in the pulse regime (5 ms pulse length, 10 Hz repetition rate) at wavelength 763 nm. At room temperature, the laser emission was achieved at 1949 nm with a high 38 % slope efficiency. With a temperature decrease, the slope efficiency increased, and the laser threshold decreased, and the laser output wavelength shifted.","PeriodicalId":376481,"journal":{"name":"Optics + Optoelectronics","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126058164","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}
David J. Hoffman, H. Bechtel, Diego A. Huyke, J. Santiago, D. DePonte, J. Koralek
Microfluidic liquid sheet jets have rapidly grown in popularity for extreme ultraviolet and soft x-ray spectroscopies as they are vacuum stable, constantly refreshing, and are easily able to reach sub-micron optical path lengths required for transmission measurements. We have recently demonstrated the generation of a new class of sheet jet comprised of two liquids (a “liquid heterostructure”) by colliding two jets of one liquid onto opposite sides of third jet of another liquid. The resulting structure is a layered sheet jet where a thin sheet of one liquid is completely enveloped by a larger sheet of a separate liquid. If the component liquids are miscible, the thin component layers result in fast diffusive mixing on submillisecond time scales based on measurements using FTIR microscopy. If the component liquids are immiscible, the resulting structure contains well-defined, large-area liquid-liquid interfaces with a minimized bulk liquid background as determined from ellipsometry and FTIR microscopy measurements. The inner liquid layer in these structures was found to be as thin as tens of nanometers, comparable to the thinnest sheet jets that can be produced. These new heterostructures provide the same benefits as conventional sheet jets for XUV and SXR spectroscopy and could enable new mix-and-probe spectroscopic techniques or support developing methods such as XUV/SXR second harmonic generation for examining buried liquid interfaces.
{"title":"Exposed interfaces and fast mixing in XFEL-friendly liquid sheets","authors":"David J. Hoffman, H. Bechtel, Diego A. Huyke, J. Santiago, D. DePonte, J. Koralek","doi":"10.1117/12.2669141","DOIUrl":"https://doi.org/10.1117/12.2669141","url":null,"abstract":"Microfluidic liquid sheet jets have rapidly grown in popularity for extreme ultraviolet and soft x-ray spectroscopies as they are vacuum stable, constantly refreshing, and are easily able to reach sub-micron optical path lengths required for transmission measurements. We have recently demonstrated the generation of a new class of sheet jet comprised of two liquids (a “liquid heterostructure”) by colliding two jets of one liquid onto opposite sides of third jet of another liquid. The resulting structure is a layered sheet jet where a thin sheet of one liquid is completely enveloped by a larger sheet of a separate liquid. If the component liquids are miscible, the thin component layers result in fast diffusive mixing on submillisecond time scales based on measurements using FTIR microscopy. If the component liquids are immiscible, the resulting structure contains well-defined, large-area liquid-liquid interfaces with a minimized bulk liquid background as determined from ellipsometry and FTIR microscopy measurements. The inner liquid layer in these structures was found to be as thin as tens of nanometers, comparable to the thinnest sheet jets that can be produced. These new heterostructures provide the same benefits as conventional sheet jets for XUV and SXR spectroscopy and could enable new mix-and-probe spectroscopic techniques or support developing methods such as XUV/SXR second harmonic generation for examining buried liquid interfaces.","PeriodicalId":376481,"journal":{"name":"Optics + Optoelectronics","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125664065","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}
L. Veisz, A. de Andres, S. Bhadoria, A. Gonoskov, M. Marklund, T. Blackburn, J. Marmolejo, D. Hanstorp
Vacuum laser acceleration (VLA) of electrons has been an intense field of research for a long time due to the extremely high (>1 TV/m) accelerating fields. However, it is very challenging to realize and only a few promising experiments have been performed which have demonstrated the principle. Here, we report on the interaction of relativistic intensity (1020 Wcm-2) sub-two optical cycle (<5 fs) laser pulses with nanotips to realize and optimize VLA. Various properties of accelerated electrons (angular distribution, charge, and electron spectrum) are measured with different intensities and carrier envelope phases of the laser pulse. Among others, waveform dependence of the electron propagation direction is observed. Furthermore, comparable or even higher electron energies beyond 10 MeV are detected with lower laser intensity, i.e., longer focusing, than with high intensity. These surprising results are reproduced using particle-in-cell simulations, which indicate a nanophotonics electron emission from the nanotip followed by VLA. In fact, the unexpected observations are a direct proof of the VLA process and provide a way to optimize it towards higher energy, isolated, attosecond electron bunch generation.
{"title":"Relativistic electron acceleration from nanotips","authors":"L. Veisz, A. de Andres, S. Bhadoria, A. Gonoskov, M. Marklund, T. Blackburn, J. Marmolejo, D. Hanstorp","doi":"10.1117/12.2669592","DOIUrl":"https://doi.org/10.1117/12.2669592","url":null,"abstract":"Vacuum laser acceleration (VLA) of electrons has been an intense field of research for a long time due to the extremely high (>1 TV/m) accelerating fields. However, it is very challenging to realize and only a few promising experiments have been performed which have demonstrated the principle. Here, we report on the interaction of relativistic intensity (1020 Wcm-2) sub-two optical cycle (<5 fs) laser pulses with nanotips to realize and optimize VLA. Various properties of accelerated electrons (angular distribution, charge, and electron spectrum) are measured with different intensities and carrier envelope phases of the laser pulse. Among others, waveform dependence of the electron propagation direction is observed. Furthermore, comparable or even higher electron energies beyond 10 MeV are detected with lower laser intensity, i.e., longer focusing, than with high intensity. These surprising results are reproduced using particle-in-cell simulations, which indicate a nanophotonics electron emission from the nanotip followed by VLA. In fact, the unexpected observations are a direct proof of the VLA process and provide a way to optimize it towards higher energy, isolated, attosecond electron bunch generation.","PeriodicalId":376481,"journal":{"name":"Optics + Optoelectronics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129140594","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}
C. Lechner, S. Casalbuoni, G. Geloni, E. Schneidmiller, S. Serkez, H. Sinn
European XFEL is a multi-beamline x-ray free-electron laser (FEL) user facility driven by a superconducting accelerator with a nominal photon energy range from 250 eV to 25 keV. To extend the photon range towards harder x-rays, an afterburner undulator based on superconducting undulator (SCU) technology is currently being planned. This afterburner undulator would be installed at the end of the already operating SASE2 hard x-ray FEL beamline. The electron bunch is microbunched by the FEL process in the SASE2 undulators and in the SCUs drives emission either at the same wavelength or at a harmonic of the upstream SASE2 undulator. In this contribution we describe numerical simulations of the potential photon output.
{"title":"Numerical simulation studies of superconducting afterburner operation at SASE2 beamline of European XFEL","authors":"C. Lechner, S. Casalbuoni, G. Geloni, E. Schneidmiller, S. Serkez, H. Sinn","doi":"10.1117/12.2669177","DOIUrl":"https://doi.org/10.1117/12.2669177","url":null,"abstract":"European XFEL is a multi-beamline x-ray free-electron laser (FEL) user facility driven by a superconducting accelerator with a nominal photon energy range from 250 eV to 25 keV. To extend the photon range towards harder x-rays, an afterburner undulator based on superconducting undulator (SCU) technology is currently being planned. This afterburner undulator would be installed at the end of the already operating SASE2 hard x-ray FEL beamline. The electron bunch is microbunched by the FEL process in the SASE2 undulators and in the SCUs drives emission either at the same wavelength or at a harmonic of the upstream SASE2 undulator. In this contribution we describe numerical simulations of the potential photon output.","PeriodicalId":376481,"journal":{"name":"Optics + Optoelectronics","volume":"113 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129404901","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}
M. Haras, M. Wlazło, W. Andrysiewicz, T. Skotnicki
Rapid growth is promoting the Internet of Things (IoT) to become one of the main branches of the semiconductor industry. Surprisingly, the IoT growth would have been even faster if economically attractive and reliable alternatives for batteries and wires had been available. Providing power supply to the IoT nodes is challenging regarding their: (i) quantity (close to 8x the human population), (ii) harsh operation environments, (iii) size (typical footprint much smaller than mm2) and (iv) hard-to-reach locations. Modern IoT node requires very small energy (less than 100μJ/cycle) to operate. Wire supply of energy is expensive and uncomfortable while using a battery requires periodic replacements/maintenance and produces tons of toxic waste. Energy Harvesting (EH) could be a solution to overcome the IoT supply difficulties offering self-supplied nodes enabling further IoT market growth. EH converts natural or waste energies (vibrations, heat losses, light, etc.) into useful energy. We present an innovative two-step conversion harvester capable of transforming light into electricity via the PieZoelectric (PZ) effect. Our approach uses a Photo- Mobile Polymer (PMP) integrated with the PZ material. PMP serves as light-to-movement transducer and PZ converts the light-induced PMP flexions into voltage. As a PZ material, a nanostructured ZnO nanorods were used as their fabrication is cheap and ready-to-use at industrial scale. ZnO performance characterization in a dedicated flexions simulator revealed energy as high as 80nJ during 55sec bending runs. This result encourages further PMP and ZnO optimization enabling extension of piezoelectrics onto light conversion.
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