Article
Engineering, Electrical & Electronic
Wei Shi, Meilin Wu, Cheng Ma, Zhiyuan Chen
Summary: This article presents a method for pulse width modulation of a nonlinear GaAs PCSS through the dual regulation of energy-storage capacitance and current-limiting resistance. The experimental results indicate that different pulse widths can be achieved by controlling the electric field intensity through the addition of different current-limiting resistances and energy-storage capacitance in the circuit.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Physics, Applied
Yicong Dong, Karen M. Dowling, Stefan P. Hau-Riege, Adam Conway, Lars F. Voss, Shaloo Rakheja
Summary: This paper presents the physics and design-space exploration of a novel pulse compression photoconductive switch (PCPS) using semi-insulating gallium arsenide (GaAs) operating in the negative differential mobility (NDM) regime of electron transport. The relationship between PCPS performance and various design options is quantified, and the optimal design parameters for higher electron confinement and superior radio-frequency (RF) metrics are discussed. The results provide guidance for experimentalists in fine-tuning the PCPS design parameters and serve as a theoretical basis for measurements of PCPS devices using GaAs and other NDM materials.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
Haina Qi, Yunrui Xie, Liu Yang, Xuehua Tang, Qianli Ma, Wensheng Yu, Xiangting Dong, Dan Li, Guixia Liu, Jinxian Wang
Summary: SAPF is a novel switch-typed anisotropic photoconductive film with tri-functionality, which can be modulated from mono-function to tri-function via light illumination. By adjusting material concentration and light conditions, its properties of photoconductivity, fluorescence, and superparamagnetism can be tuned.
APPLIED MATERIALS TODAY
(2021)
Article
Engineering, Electrical & Electronic
Eric T. Der, Thomas R. Jones, Alden Fisher, Michael D. Sinanis, Kambiz Moez, Douglas W. Barlage, Dimitrios Peroulis
Summary: This paper presents the design, fabrication, and measurement of a silicon micromachined photoconductive evanescent (EVA)-mode waveguide switch operating in a single-pole double-throw (SPDT) configuration. The proposed design shows promise for 5G and 6G communication backhaul devices, providing low-loss propagation of signals and high isolation within the W-band.
IEEE MICROWAVE AND WIRELESS TECHNOLOGY LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Langning Wang, Xu Chu, Muyu Yi, Jinmei Yao, Tao Xun, Hanwu Yang
Summary: The SiC vertical photoconductive switch with an axial optical internal reflection trap improves the ON-state performance significantly by increasing both the light absorption and output current. The structure with the reflective trapping arrangement demonstrates a 2.5x improvement in photoelectric conversion responsivity compared to regular axial illumination.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Engineering, Electrical & Electronic
Long Hu, Jia Huang, Xianghong Yang, Xin Shen, Yue Sun
Summary: The operation mechanism of a gallium nitride (GaN) photoconductive semiconductor switch (PCSS) based on a semi-insulating (SI) wafer was analyzed using a physics-based numerical simulation. The study found that the switch can achieve quasi-avalanche mode and ultrafast switching under specific bias conditions, which is consistent with experimental results. The physics of multiple powerful avalanche domains and their connection to the negative differential mobility (NDM) of electrons were discussed.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Engineering, Electrical & Electronic
Zhuoyun Feng, Chongbiao Luan, Longfei Xiao, Yangfan Li, Huiru Sha, Xun Sun, Xiufang Chen, Xiangang Xu, Hongtao Li
Summary: Radial lateral structure photoconductive switches fabricated using vanadium-doped 4H-SiC and high-purity 4H-SiC materials are studied in this work. The switches are triggered by 355 and 532 nm lasers, and their performance is compared under different applied voltages and laser energies. Experimental results demonstrate that the conduction current is larger when the laser is incident from the rear. Simulations of the current density distribution provide theoretical support for this phenomenon and indicate that the high-purity material has higher conduction current than the vanadium-doped material under the same conditions.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2023)
Article
Nanoscience & Nanotechnology
Bin Wang, Langning Wang, Xinyue Niu, Xu Chu, Muyu Yi, Jinmei Yao, Tao Xun
Summary: The breakdown behavior of a V-doped 4H silicon carbide photoconductive switch with a transparent electrode under a high electric field was studied. The breakdown of the device was found to be due to the interaction between the laser and the aluminum doped zinc oxide transparent electrode on the device surface, resulting in the melting of the transparent electrode. The direct illuminate of the laser could form a field enhancement effect at the junction of the substrate and the transparent electrode, leading to device damage and pre-breakdown formation.
Proceedings Paper
Engineering, Electrical & Electronic
Jiyang Shang, Yu Zhang, Haiyang Ding, Peng Luo, Minjia Lin, Chongbin Yao
Summary: The complementary coplanar interdigital electrode photoconductive switch based on vanadium-nitrogen doped 4H-SiC bulk material significantly improves voltage capability and reduces conductive resistance. With stable output waveform, small jitter and high power, the switch has demonstrated potential applications in microwave systems.
OPTOELECTRONIC DEVICES AND INTEGRATION X
(2021)
Article
Optics
Cheng Ma, Meilin Wu, Wennan Wang, Yaqiong Jia, Wei Shi
Summary: This paper presents the design of a three-layer GaAs photoconductive semiconductor switch capable of withstanding high voltages from 20 to 35 kV, with the highest reported values for maximum avalanche gain and minimum on-state resistance. The influence of bias voltage on avalanche stability is analyzed, with jitter values calculated at different bias voltages. This work offers guidance for the design of semiconductor switches with high voltage and high gain.
Article
Engineering, Electrical & Electronic
Ming Xu, Hangtian Dong, Chun Liu, Yi Wang, Long Hu, Chunpeng Lan, Wei Luo, Harald Schneider
Summary: This study focuses on the transient performance of gallium arsenide photoconductive semiconductor switches (PCSSs) triggered by high-energy laser diodes under high bias electric fields at both single-shot and high frequency excitation. The results show that the electric field has a significant impact on the nonlinear characteristics, with a high carrier avalanche multiplication factor.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Engineering, Electrical & Electronic
Pyeung Hwi Choi, Yong Pyo Kim, Min-Seong Kim, Jiheon Ryu, Sung-Hyun Baek, Sung-Min Hong, Sungbae Lee, Jae-Hyung Jang
Summary: High purity semi-insulating 4H-silicon carbide was utilized to fabricate lateral and vertical photoconductive semiconductor switches. Among them, the vertical PCSS demonstrated superior performance in terms of minimum ON-state resistance and output pulse amplitude.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Nanoscience & Nanotechnology
Hongqi Wang, Liqiang Tian, Wei Shi, Cheng Ma, Meilin Wu, Kaipeng Chen
Summary: Previous studies have shown that changing the electrode structures of GaAs PCSS can have a significant impact on the local electric field and current density. This research focuses on optimizing the surface contact electrode structure of GaAs PCSS, and numerical simulations are used to study the distribution of electric field and current density within the device. The results indicate that the embedded 172 degrees isosceles trapezoid electrode structure is the most favorable for improving the withstand voltage and current carrying capability of GaAs PCSS.
Article
Engineering, Electrical & Electronic
Ye Tian, Xuan Chen, Jinyue Xie, Kang Zhang, Zejia Zhao, Lisa Liu, Feng Song
Summary: A mathematical model of a ring total reflection structure based on SiC semiconductor material is established to improve the synchronization of photoelectric response and the working life of the SiC photoconductive switch. The influence of structural parameters on the absorption rate and uniformity of the device is analyzed. Two sets of structural parameters with high absorption and uniformity are simulated, and compensation of regions with less light distribution can be achieved by adding reflectors.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Computer Science, Information Systems
Meilin Wu, Wei Shi
Summary: This study investigates the output electric pulse characteristics of gallium arsenide photoconductive semiconductor switch (GaAs PCSS) with a bias voltage of 20 kV and pulse width of about 100 ns. By designing optical paths, the absorption rate of the trigger optical at a wavelength of 1064 nm was measured to be 24.8%. The avalanche multiplication rates of carriers were calculated at bias voltages of 16 kV-20 kV. The relationship between the output current waveform and the residual charge in the energy storage capacitor at a bias voltage of 20 kV was analyzed. The research has important significance for the application of GaAs PCSS in frontier science.
Article
Optics
Ehsan Alimohammadian, Kim Lammers, Alessandro Alberucci, Gligor Djogo, Chandroth P. Jisha, Stefan Nolte, Peter R. Herman
Summary: The formation of volumetric nanogratings in fused silica by femtosecond laser pulses allows for manipulation of physical shape and optical properties. The nanogratings follow the elongation effects induced by conical-shaped phase fronts, enabling a scaling up of the writing volume. Control of the conical phase front angle provides flexible ways to tune macroscopic optical properties.
Article
Optics
Moritz Bartnick, Gayathri Bharathan, Thorsten A. Goebel, Ria G. Kraemer, Stefan Nolte, Camille-Sophie Bres
Summary: We have developed a widely tunable mode-locked thulium-doped fiber laser based on a robust chirped fiber Bragg grating (CFBG). By applying mechanical tension and compression, the CFBG achieved an overall tunability of 20.1 nm, ranging from 2022.1 nm to 2042.2 nm. The mode-locked pulse train from this fiber laser has a repetition rate of 9.4 MHz, average power of 12.6 dBm, and pulse duration between 9.0 ps and 12.8 ps. This is the first demonstration of a tunable mode-locked thulium-doped fiber laser operating beyond 2 μm using a CFBG as a wavelength-selective element.
Article
Optics
Xiaodong Zhao, Matthias Baudisch, Marcus Beutler, Thomas Gabler, Stefan Nolte, Roland Ackermann
Summary: We present an optical parametric amplifier (OPA) that generates pulses with a maximum energy of approximately 200 μJ in the wavelength range of 700-950 nm and duration of about 1 ps. The OPA is driven by a 1 ps pulse with an energy of approximately 2.5 mJ at a frequency of 1 kHz, provided by a commercial thin-disk laser. By using the output pulse of the OPA as a pump, the thin-disk laser generates Stokes light at 1030 nm and uses the second harmonic (515 nm) as a probe for investigating coherent anti-Stokes Raman scattering (CARS) of N-2 and CO2 at different temperatures.
Article
Optics
Anne-Sophie Munser, Marcus Trost, Sven Schroeder, Martina Graf, Miriam A. Rosenbaum, Andreas Tuennermann
Summary: Due to its high sensitivity and quick measurement principle, angle-resolved scattering (ARS) measurements show promising potential as a rapid analysis tool for bacterial cells, especially at small sample sizes and low cell numbers. This study has demonstrated that scattered light from various bacterial cell samples can be analyzed at the single-cell level, which is a significant benefit compared to time-consuming conventional methods that require hours or days of cellular growth. With the proposed setup and data analysis method, it is possible to detect scatter differences among cell types as well as measure cell concentration.
Article
Physics, Applied
Markus Blothe, Maxime Chambonneau, Stefan Nolte
Summary: In this study, laser-based amorphization on the back surface of a crystalline silicon sample was investigated. By utilizing laser irradiation and Bessel beam shaping, the crystalline silicon was transformed into an amorphous state, resulting in the formation of subwavelength periodic surface structures. This research provides new possibilities for processing in-built microelectronic devices.
APPLIED PHYSICS LETTERS
(2022)
Article
Optics
Gia Quyet Ngo, Emad Najafidehaghani, Ziyang Gan, Sara Khazaee, Malte Per Siems, Antony George, Erik P. Schartner, Stefan Nolte, Heike Ebendorff-Heidepriem, Thomas Pertsch, Alessandro Tuniz, Markus A. Schmidt, Ulf Peschel, Andrey Turchanin, Falk Eilenberger
Summary: This study demonstrates a method to achieve second-harmonic generation in functionalized optical fibers by directly growing highly nonlinear MoS2 monolayers on the fiber's core. The approach is scalable and can be generalized to other materials and waveguide systems.
Article
Materials Science, Multidisciplinary
Andreas Tuennermann, Carsten Momma, Stefan Nolte
Summary: Ultrashort pulse lasers have been widely used in precise micromachining. This article presents a brief perspective on the development of this innovative technology from the 1990s until today.
APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
(2023)
Article
Materials Science, Multidisciplinary
Shawon Alam, Pallabi Paul, Vivek Beladiya, Paul Schmitt, Olaf Stenzel, Marcus Trost, Steffen Wilbrandt, Christian Muehlig, Sven Schroeder, Gabor Matthaeus, Stefan Nolte, Sebastian Riese, Felix Otto, Torsten Fritz, Alexander Gottwald, Adriana Szeghalmi
Summary: Absorption losses and laser-induced damage threshold (LIDT) are the main limitations for the development of optical coatings for high-power laser optics. This study developed heterostructures using sub-nanometer thin films of SiO2 and HfO2 with the plasma-enhanced atomic layer deposition (PEALD) technique. Various thin-film characterization techniques were employed to extract optical constants, residual stress, layer formation, and functional groups of the heterostructures. The heterostructures showed tunable refractive index, bandgap, improved optical losses, and LIDT properties.
Article
Optics
Abhik Chakraborty, Parijat Barman, Ankit Kumar Singh, Xiaofei Wu, Denis A. Akimov, Tobias Meyer-Zedler, Stefan Nolte, Carsten Ronning, Michael Schmitt, Juergen Popp, Jer-Shing Huang
Summary: Plasmonic enhancement of nonlinear light-matter interaction can be achieved by optimizing resonant plasmonic modes that match the wavelengths involved in the nonlinear optical process. This study investigates the generation and enhancement of broadband four-wave mixing in a plasmonic azimuthally chirped grating (ACG), which allows for control of near and far field interactions across a wide range of wavelengths. The mechanism responsible for field enhancement in the ACG platform depends on the interplay between groove geometry and grating periodicity. This work elucidates the collective contribution of localized surface plasmon resonance and plasmonic surface lattice resonance to the enhancement of broadband FWM in the ACG.
LASER & PHOTONICS REVIEWS
(2023)
Article
Optics
Evgeny A. Perevezentsev, Malte Per Siems, Daniel Richter, Ivan B. Mukhin, Ria G. Kraemer, Anton I. Gorokhov, Mikhail R. Volkov, Stefan Nolte
Summary: The first steps towards developing and characterizing next-generation chirped volume Bragg gratings (CVBGs) using fs laser inscription were taken. CVBGs with a 3 x 3 mm2 aperture and a length of almost 12 mm were successfully created on fused silica. Despite the polarization and phase distortions caused by mechanical stresses, a possible solution to this problem was proposed. The small change in the linear absorption coefficient of fused silica allows for the utilization of these gratings in high average power lasers.
Article
Optics
Fatemeh Abtahi, Pallabi Paul, Sebastian Beer, Athira Kuppadakkath, Anton Pakhomov, Adriana Szeghalmi, Stefan Nolte, Frank Setzpfandt, Falk Eilenberger
Summary: Second-harmonic generation (SHG) is observed in periodic stacks of alternating, subwavelength dielectric layers due to the broken symmetry at the surface. The surface SHG is significantly enhanced by the large number of surfaces in these stacks. Experimental results on SiO2/TiO2 multilayer stacks grown by PEALD demonstrate substantial SHG under large angles of incidence, surpassing that of simple interfaces. The experimental results are in agreement with theoretical calculations.
Article
Optics
Xiaodong Zhao, Andre Boden, Stefan Nolte, Roland Ackermann
Summary: We investigate the spectral properties of filamentation induced by ps laser in air using a thin-disk based amplifier with a central wavelength of 1030 nm, maximum pulse energy of 60 mJ, and a repetition rate of 1 kHz. The broad spectrum generated by filamentation is found to be capable of exciting ro-vibrational Raman transitions in N2, O2, and CH4. We probe the excitation using the second harmonic (515 nm) to generate CARS signals in air, and study the influence of optical windows on the CARS signal for combustion and gasification diagnostics applications.
Article
Materials Science, Multidisciplinary
Maxime Chambonneau, Qingfeng Li, Markus Blothe, Stree Vithya Arumugam, Stefan Nolte
Summary: Although ultrafast laser welding is not suitable for joining silicon samples due to nonlinear propagation effects, these limitations can be overcome by enhancing local absorption at the interface through metallic nanolayer deposition. By combining the enhanced absorption with filament relocation during ultrafast laser irradiation, efficient joining of silicon samples is achieved. Shear joining strengths exceeding 4 MPa can be obtained with 21 nm gold nanolayers, promising applications in microelectronics, optics, and astronomy.
ADVANCED PHOTONICS RESEARCH
(2023)
Article
Optics
Chandroth P. Jisha, Stree Vithya Arumugam, Lorenzo Marrucci, Stefan Nolte, Alessandro Alberucci
Summary: We investigate waveguides based on the Pancharatnam-Berry phase, obtained by rotation of the optic axis in a birefringent medium. We study the case where accumulation of geometric phase is present. The interplay between different contributions to the optical potential is addressed and the polarization structure of the quasimodes is observed to evolve continuously.
Proceedings Paper
Optics
Arno Klenke, A. Steinkopff, C. Aleshire, C. Jauregui, Stefan Kuhn, Johannes Nold, Christian Hupel, Sigrun Hein, Steffen Schulze, Nicoletta Haarlammert, Thomas Schreiber, Andreas Tuennermann, Jens Limpert
Summary: In this paper, a rod-type, Ytterbium-doped, multicore fiber with 4x4 cores is presented. This fiber is used in a CPA setup for coherent beam combination of femtosecond pulses. High average powers of up to 507 W after combination and compression are achieved at 10 MHz repetition rate. A high combination efficiency of 85% is realized together with excellent beam quality. Additionally, up to 600 µJ pulse energy is measured in a lower repetition rate configuration.
FIBER LASERS XIX: TECHNOLOGY AND SYSTEMS
(2022)
