Pub Date : 2024-09-16DOI: 10.1109/JSTQE.2024.3462489
Hang Lu;Omar Alkhazragi;Yue Wang;Tien Khee Ng;Boon S. Ooi
Random numbers, as a cornerstone in the interconnected digital world, are used in secure cryptographic protocols for commercial transactions, computing, and communications. Instead of the traditional deterministic pseudorandom numbers, physical random number generation (RNG) is currently being investigated by leveraging the chaotic dynamics of semiconductor lasers for improved security, speed, and compactness. However, those RNG approaches suffer from discrete and expensive components with limited scalability due to the enormous footprint imposed by the edge-emitting configuration, which increases the cost and impedes practical use in integrated devices. Herein, we demonstrated a parallel chip-scale RNG by first harnessing the self-chaotic dynamics of free-running broad-area vertical-cavity surface-emitting lasers (BA-VCSELs). The intense mode interaction within the broad-area cavity provides a robust foundation for ultrafast dynamics, allowing for high-security and high-speed RNG. Comparative analysis with a small-area quasi-single-mode VCSEL (QSM-VCSEL) confirms the efficacy of achieving high-speed RNG with hundreds of Gb/s from a single BA-VCSEL channel and 2 Tb/s from four channels as a proof-of-concept device. Given the easy fabrication and high scalability of VCSELs, this finding opens avenues for low-cost, massively parallel high-speed RNG chips with photodetector integration, unveiling opportunities for fields demanding unprecedented RNG rates and high levels of cybersecurity.
{"title":"Parallel On-Chip Physical Random Number Generator Based on Self-Chaotic Dynamics of Free-Running Broad-Area VCSEL Array","authors":"Hang Lu;Omar Alkhazragi;Yue Wang;Tien Khee Ng;Boon S. Ooi","doi":"10.1109/JSTQE.2024.3462489","DOIUrl":"10.1109/JSTQE.2024.3462489","url":null,"abstract":"Random numbers, as a cornerstone in the interconnected digital world, are used in secure cryptographic protocols for commercial transactions, computing, and communications. Instead of the traditional deterministic pseudorandom numbers, physical random number generation (RNG) is currently being investigated by leveraging the chaotic dynamics of semiconductor lasers for improved security, speed, and compactness. However, those RNG approaches suffer from discrete and expensive components with limited scalability due to the enormous footprint imposed by the edge-emitting configuration, which increases the cost and impedes practical use in integrated devices. Herein, we demonstrated a parallel chip-scale RNG by first harnessing the self-chaotic dynamics of free-running broad-area vertical-cavity surface-emitting lasers (BA-VCSELs). The intense mode interaction within the broad-area cavity provides a robust foundation for ultrafast dynamics, allowing for high-security and high-speed RNG. Comparative analysis with a small-area quasi-single-mode VCSEL (QSM-VCSEL) confirms the efficacy of achieving high-speed RNG with hundreds of Gb/s from a single BA-VCSEL channel and 2 Tb/s from four channels as a proof-of-concept device. Given the easy fabrication and high scalability of VCSELs, this finding opens avenues for low-cost, massively parallel high-speed RNG chips with photodetector integration, unveiling opportunities for fields demanding unprecedented RNG rates and high levels of cybersecurity.","PeriodicalId":13094,"journal":{"name":"IEEE Journal of Selected Topics in Quantum Electronics","volume":"31 2: Pwr. and Effic. Scaling in Semiconductor Lasers","pages":"1-11"},"PeriodicalIF":4.3,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10681270","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-13DOI: 10.1109/JSTQE.2024.3460738
Olivier Spitz;Luis E. Maldonado-Castillo;Mark A. Berrill;Yehuda Braiman
We combine gain switching and external optical feedback to achieve high-power coherent pulsing in a large array of semiconductor lasers. The simulations are performed in the framework of the Lang-Kobayashi model with modulation of the electrical bias. Long-range coupling in the network of emitters and precise tuning of the modulation frequency are key parameters to obtain both phase-locking between the emitters, and reproducible, periodic, high intensity bursts, i.e. robust, coherent pulsing. The configuration we present here relies on non-filtered conventional optical feedback and allows achieving phase-locked pulsing across the array, including at modulation frequencies that are resonant and not resonant with the external cavity frequency and its harmonics. This work impacts on the realization of phase-synchronized pulsed sources from semiconductor laser arrays and provides insight for the generation of complex nonlinear dynamics in large networks of oscillators.
{"title":"Optimization of Combined Coherent Gain-Switch Pulsing in a Large Array of Semiconductor Lasers","authors":"Olivier Spitz;Luis E. Maldonado-Castillo;Mark A. Berrill;Yehuda Braiman","doi":"10.1109/JSTQE.2024.3460738","DOIUrl":"10.1109/JSTQE.2024.3460738","url":null,"abstract":"We combine gain switching and external optical feedback to achieve high-power coherent pulsing in a large array of semiconductor lasers. The simulations are performed in the framework of the Lang-Kobayashi model with modulation of the electrical bias. Long-range coupling in the network of emitters and precise tuning of the modulation frequency are key parameters to obtain both phase-locking between the emitters, and reproducible, periodic, high intensity bursts, i.e. robust, coherent pulsing. The configuration we present here relies on non-filtered conventional optical feedback and allows achieving phase-locked pulsing across the array, including at modulation frequencies that are resonant and not resonant with the external cavity frequency and its harmonics. This work impacts on the realization of phase-synchronized pulsed sources from semiconductor laser arrays and provides insight for the generation of complex nonlinear dynamics in large networks of oscillators.","PeriodicalId":13094,"journal":{"name":"IEEE Journal of Selected Topics in Quantum Electronics","volume":"31 2: Pwr. and Effic. Scaling in Semiconductor Lasers","pages":"1-14"},"PeriodicalIF":4.3,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142248329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-10DOI: 10.1109/JSTQE.2024.3457154
Shangda Li;Shang Liu;Hryhorii Stanchu;Grey Abernathy;Baohua Li;Shui-Qing Yu;Xiaoxin Wang;Jifeng Liu
Germanium-tin (GeSn) alloys are promising materials for infrared photonics due to their tunable direct bandgap and compatibility with silicon technology. However, implantation doping of GeSn layers to achieve more sophisticated doping profiles faces challenges, particularly in restoring crystallinity after ion implantation. In this work, we investigate the recrystallization of ion-implanted GeSn thin films through rapid thermal annealing (RTA) and laser annealing. We propose a model for Sn diffusion pathways that lead to surface segregation based on distinct surface segregation patterns in GeSn layers with varying degrees of amorphization. Our results demonstrate that RTA at 400 °C effectively restores the crystallinity for GeSn thin films with up to 10.7 at.% Sn composition, despite a small amount of Sn surface segregation, while 532 nm wavelength CW laser annealing at a threshold power density above 52 kW/cm 2 also achieves recrystallization without Sn segregation. These findings contribute to understanding Sn segregation mechanisms and optimizing recrystallization conditions for GeSn after implantation, advancing its potential for infrared photonics applications.
{"title":"Ion Implantation Damage Recovery in GeSn Thin Films","authors":"Shangda Li;Shang Liu;Hryhorii Stanchu;Grey Abernathy;Baohua Li;Shui-Qing Yu;Xiaoxin Wang;Jifeng Liu","doi":"10.1109/JSTQE.2024.3457154","DOIUrl":"10.1109/JSTQE.2024.3457154","url":null,"abstract":"Germanium-tin (GeSn) alloys are promising materials for infrared photonics due to their tunable direct bandgap and compatibility with silicon technology. However, implantation doping of GeSn layers to achieve more sophisticated doping profiles faces challenges, particularly in restoring crystallinity after ion implantation. In this work, we investigate the recrystallization of ion-implanted GeSn thin films through rapid thermal annealing (RTA) and laser annealing. We propose a model for Sn diffusion pathways that lead to surface segregation based on distinct surface segregation patterns in GeSn layers with varying degrees of amorphization. Our results demonstrate that RTA at 400 °C effectively restores the crystallinity for GeSn thin films with up to 10.7 at.% Sn composition, despite a small amount of Sn surface segregation, while 532 nm wavelength CW laser annealing at a threshold power density above 52 kW/cm\u0000<sup>2</sup>\u0000 also achieves recrystallization without Sn segregation. These findings contribute to understanding Sn segregation mechanisms and optimizing recrystallization conditions for GeSn after implantation, advancing its potential for infrared photonics applications.","PeriodicalId":13094,"journal":{"name":"IEEE Journal of Selected Topics in Quantum Electronics","volume":"31 1: SiGeSn Infrared Photon. and Quantum Electronics","pages":"1-8"},"PeriodicalIF":4.3,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142198906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This work introduces a comprehensive simulation tool that provides a robust 1D Schrödinger – Poisson solver for modeling the electrostatics of heterostructures with an arbitrary number of layers, and non-uniform doping profiles along with the treatment of partial ionization of dopants at low temperatures. The effective masses are derived from the first-principles calculations. The solver is used to characterize three Ge $_{text{1-x}}$ Sn $_{text{x}}$ /Ge heterostructures with non-uniform doping profiles and determine the subband structure at various temperatures. The simulation results of the sheet carrier densities show excellent agreement with the experimentally extracted data, thus demonstrating the capabilities of the solver.
{"title":"Modeling and Simulation of Electrostatics of Ge$_{text{1-x}}$Sn$_{text{x}}$ Layers Grown on Ge Substrates","authors":"Siddhant Gangwal;Shunda Chen;Tianshu Li;Tzu-Ming Lu;Dragica Vasileska","doi":"10.1109/JSTQE.2024.3456590","DOIUrl":"10.1109/JSTQE.2024.3456590","url":null,"abstract":"This work introduces a comprehensive simulation tool that provides a robust 1D Schrödinger \u0000<bold>–</b>\u0000 Poisson solver for modeling the electrostatics of heterostructures with an arbitrary number of layers, and non-uniform doping profiles along with the treatment of partial ionization of dopants at low temperatures. The effective masses are derived from the first-principles calculations. The solver is used to characterize three Ge\u0000<inline-formula><tex-math>$_{text{1-x}}$</tex-math></inline-formula>\u0000Sn\u0000<inline-formula><tex-math>$_{text{x}}$</tex-math></inline-formula>\u0000/Ge heterostructures with non-uniform doping profiles and determine the subband structure at various temperatures. The simulation results of the sheet carrier densities show excellent agreement with the experimentally extracted data, thus demonstrating the capabilities of the solver.","PeriodicalId":13094,"journal":{"name":"IEEE Journal of Selected Topics in Quantum Electronics","volume":"31 1: SiGeSn Infrared Photon. and Quantum Electronics","pages":"1-8"},"PeriodicalIF":4.3,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142198907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) is a powerful technique for elemental compositional analysis and depth profiling of materials. However, it encounters the problem of matrix effects that hinder its application. In this work, we introduce a pioneering ToF-SIMS calibration method tailored for SixGeySnz ternary alloys. SixGe1-x and Ge1-zSnz binary alloys with known compositions are used as calibration reference samples. Through a systematic SIMS quantification study of SiGe and GeSn binary alloys, we unveil a linear correlation between secondary ion intensity ratio and composition ratio for both SiGe and GeSn binary alloys, effectively mitigating the matrix effects. Extracted relative sensitivity factor (RSF) value from SixGe1-x (0.07 < x < 0.83) and Ge1-zSnz (0.066 < z < 0.183) binary alloys are subsequently applied to those of SixGeySnz (0.011 < x < 0.113, 0.863 < y < 0.935 and 0.023 < z < 0.103) ternary alloys for elemental compositions quantification. These values are cross-checked by Atom Probe Tomography (APT) analysis, an indication of the great accuracy and reliability of as-developed ToF-SIMS calibration process. The proposed method and its reference sample selection strategy in this work provide a low-cost as well as simple-to-follow calibration route for SiGeSn composition analysis, thus driving the development of next-generation multifunctional SiGeSn-related semiconductor devices.
{"title":"Composition Quantification of SiGeSn Alloys Through Time-of-Flight Secondary Ion Mass Spectrometry: Calibration Methodologies and Validation With Atom Probe Tomography","authors":"Haochen Zhao;Shang Liu;Suho Park;Xu Feng;Zhaoquan Zeng;James Kolodzey;Shui-Qing Yu;Jifeng Liu;Yuping Zeng","doi":"10.1109/JSTQE.2024.3456439","DOIUrl":"10.1109/JSTQE.2024.3456439","url":null,"abstract":"Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) is a powerful technique for elemental compositional analysis and depth profiling of materials. However, it encounters the problem of matrix effects that hinder its application. In this work, we introduce a pioneering ToF-SIMS calibration method tailored for SixGeySnz ternary alloys. SixGe1-x and Ge1-zSnz binary alloys with known compositions are used as calibration reference samples. Through a systematic SIMS quantification study of SiGe and GeSn binary alloys, we unveil a linear correlation between secondary ion intensity ratio and composition ratio for both SiGe and GeSn binary alloys, effectively mitigating the matrix effects. Extracted relative sensitivity factor \u0000<italic>(RSF)</i>\u0000 value from SixGe1-x (0.07 < x < 0.83) and Ge1-zSnz (0.066 < z < 0.183) binary alloys are subsequently applied to those of SixGeySnz (0.011 < x < 0.113, 0.863 < y < 0.935 and 0.023 < z < 0.103) ternary alloys for elemental compositions quantification. These values are cross-checked by Atom Probe Tomography (APT) analysis, an indication of the great accuracy and reliability of as-developed ToF-SIMS calibration process. The proposed method and its reference sample selection strategy in this work provide a low-cost as well as simple-to-follow calibration route for SiGeSn composition analysis, thus driving the development of next-generation multifunctional SiGeSn-related semiconductor devices.","PeriodicalId":13094,"journal":{"name":"IEEE Journal of Selected Topics in Quantum Electronics","volume":"31 1: SiGeSn Infrared Photon. and Quantum Electronics","pages":"1-8"},"PeriodicalIF":4.3,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142198908","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-06DOI: 10.1109/JSTQE.2024.3455548
Jingwei Li;Ruixuan Wang;Haipeng Zheng;Zhensheng Jia;Qing Li
A soliton microcomb can play a crucial role in narrow-grid optical communications by replacing many independently operated lasers in wavelength-division multiplexing systems. In this work, we designed and demonstrated power-efficient soliton microcombs with 100-GHz free spectral range in an integrated 4H-SiC platform. The combination of enabling technologies, including efficient fiber coupling (3 dB insertion loss), high-quality-factor microrings (intrinsic quality factors up to 5.7 million), and the employment of the Raman effect for adiabatic accessing of the soliton state, has enabled the demonstration of soliton pump power as low as 6 mW while supporting comb powers above −20 dBm per line near the pump wavelength.
{"title":"Silicon Carbide Soliton Microcomb Generation for Narrow-Grid Optical Communications","authors":"Jingwei Li;Ruixuan Wang;Haipeng Zheng;Zhensheng Jia;Qing Li","doi":"10.1109/JSTQE.2024.3455548","DOIUrl":"10.1109/JSTQE.2024.3455548","url":null,"abstract":"A soliton microcomb can play a crucial role in narrow-grid optical communications by replacing many independently operated lasers in wavelength-division multiplexing systems. In this work, we designed and demonstrated power-efficient soliton microcombs with 100-GHz free spectral range in an integrated 4H-SiC platform. The combination of enabling technologies, including efficient fiber coupling (3 dB insertion loss), high-quality-factor microrings (intrinsic quality factors up to 5.7 million), and the employment of the Raman effect for adiabatic accessing of the soliton state, has enabled the demonstration of soliton pump power as low as 6 mW while supporting comb powers above −20 dBm per line near the pump wavelength.","PeriodicalId":13094,"journal":{"name":"IEEE Journal of Selected Topics in Quantum Electronics","volume":"30 5: Microresonator Frequency Comb Technologies","pages":"1-6"},"PeriodicalIF":4.3,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142225346","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-05DOI: 10.1109/JSTQE.2024.3448914
Di Liang;Mengyue Xu;Long Chen;Haisheng Rong;Andreas Bechtolsheim
{"title":"The Future of Optical Modulation","authors":"Di Liang;Mengyue Xu;Long Chen;Haisheng Rong;Andreas Bechtolsheim","doi":"10.1109/JSTQE.2024.3448914","DOIUrl":"https://doi.org/10.1109/JSTQE.2024.3448914","url":null,"abstract":"","PeriodicalId":13094,"journal":{"name":"IEEE Journal of Selected Topics in Quantum Electronics","volume":"30 4: Adv. Mod. and Int. beyond Si and InP-based Plt.","pages":"1-6"},"PeriodicalIF":4.3,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10666944","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142143665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-05DOI: 10.1109/JSTQE.2024.3454954
Jiechao Jiang;Nonso Martin Chetuya;Joseph H Ngai;Gordon J. Grzybowski;Efstathios I. Meletis
Epitaxial growth of GeSn films directly on (0001) sapphire substrates, has not been considered as a feasible task. Here, an ultra-thin and a 1 μm thick Ge 1-x Sn x (x≤0.1) film were deposited on (0001) sapphire substrates at 475 °C and 367 °C, respectively, through remote plasma-enhanced chemical vapor deposition (RPECVD). The ultra-thin Ge 1-x Sn x film (deposited at 475 °C) exhibits a distinct epitaxial/twin mushroom-like island morphology with a height ranging from 30-45 nm and a lateral width ranging from 40 - 200 nm. The Ge 1-x Sn x islands are covered by a ∼4 nm thick surface layer of Sn-rich amorphous material and present an atomically sharp and robust interface with the substrate. The epitaxial Ge 1-x Sn x lattices coherently join with the Al layer of the sapphire substrate. The 1 μm thick Ge 1-x Sn x film (deposited at 367 °C) consists of a thin epitaxial/twin layer below a nanocrystalline columnar layer. The nanocrystalline grains have varying Sn content that exceeds that in the epitaxial structure. The epitaxial/twin layer in this film has an ∼1 nm thick highly disrupted near amorphous layer at the interface. Quasiperiodic, two-dimensional hexagonal networks of misfit dislocations are formed at the interfaces of both films to accommodate the misfit strain. The dislocation periodic length was 13.3 Å and 13.1 Å for the films deposited at 475 °C and 367 °C, respectively. The epitaxial structures in both films have an identical orientation relationship of (111) GeSn //(0001) Sapphire , $[ {1bar{1}0} ]$GeSn // $[ {2bar{1}bar{1}0} ]$Sapphire , $[ {21bar{1}} ]$GeSn // $[ {1bar{1}00} ]$Sapphire with the substrate, exhibiting lattice mismatches of ∼15% between the (220) GeSn and the $( {11bar{2}0} )$ Al 2 O 3 along the interface plane and -24% between the (111) GeSn and the (0003) Al 2 O 3 planes along the film growth direction. The observed microstructures provide valuable feedback that can be used to optimize the RPECVD process for better quality epitaxial GeSn on (0001) sapphire substrates with no buffer layer required.
{"title":"Transmission Electron Microscopy Studies of Bufferless Epitaxial GeSn on (0001) Sapphire","authors":"Jiechao Jiang;Nonso Martin Chetuya;Joseph H Ngai;Gordon J. Grzybowski;Efstathios I. Meletis","doi":"10.1109/JSTQE.2024.3454954","DOIUrl":"10.1109/JSTQE.2024.3454954","url":null,"abstract":"Epitaxial growth of GeSn films directly on (0001) sapphire substrates, has not been considered as a feasible task. Here, an ultra-thin and a 1 μm thick Ge\u0000<sub>1-x</sub>\u0000Sn\u0000<sub>x</sub>\u0000 (x≤0.1) film were deposited on (0001) sapphire substrates at 475 °C and 367 °C, respectively, through remote plasma-enhanced chemical vapor deposition (RPECVD). The ultra-thin Ge\u0000<sub>1-x</sub>\u0000Sn\u0000<sub>x</sub>\u0000 film (deposited at 475 °C) exhibits a distinct epitaxial/twin mushroom-like island morphology with a height ranging from 30-45 nm and a lateral width ranging from 40 - 200 nm. The Ge\u0000<sub>1-x</sub>\u0000Sn\u0000<sub>x</sub>\u0000 islands are covered by a ∼4 nm thick surface layer of Sn-rich amorphous material and present an atomically sharp and robust interface with the substrate. The epitaxial Ge\u0000<sub>1-x</sub>\u0000Sn\u0000<sub>x</sub>\u0000 lattices coherently join with the Al layer of the sapphire substrate. The 1 μm thick Ge\u0000<sub>1-x</sub>\u0000Sn\u0000<sub>x</sub>\u0000 film (deposited at 367 °C) consists of a thin epitaxial/twin layer below a nanocrystalline columnar layer. The nanocrystalline grains have varying Sn content that exceeds that in the epitaxial structure. The epitaxial/twin layer in this film has an ∼1 nm thick highly disrupted near amorphous layer at the interface. Quasiperiodic, two-dimensional hexagonal networks of misfit dislocations are formed at the interfaces of both films to accommodate the misfit strain. The dislocation periodic length was 13.3 Å and 13.1 Å for the films deposited at 475 °C and 367 °C, respectively. The epitaxial structures in both films have an identical orientation relationship of (111)\u0000<sub>GeSn</sub>\u0000//(0001)\u0000<sub>Sapphire</sub>\u0000, \u0000<inline-formula><tex-math>$[ {1bar{1}0} ]$</tex-math></inline-formula>\u0000<sub>GeSn</sub>\u0000//\u0000<inline-formula><tex-math>$[ {2bar{1}bar{1}0} ]$</tex-math></inline-formula>\u0000<sub>Sapphire</sub>\u0000, \u0000<inline-formula><tex-math>$[ {21bar{1}} ]$</tex-math></inline-formula>\u0000<sub>GeSn</sub>\u0000//\u0000<inline-formula><tex-math>$[ {1bar{1}00} ]$</tex-math></inline-formula>\u0000<sub>Sapphire</sub>\u0000 with the substrate, exhibiting lattice mismatches of ∼15% between the (220) GeSn and the \u0000<inline-formula><tex-math>$( {11bar{2}0} )$</tex-math></inline-formula>\u0000 Al\u0000<sub>2</sub>\u0000O\u0000<sub>3</sub>\u0000 along the interface plane and -24% between the (111) GeSn and the (0003) Al\u0000<sub>2</sub>\u0000O\u0000<sub>3</sub>\u0000 planes along the film growth direction. The observed microstructures provide valuable feedback that can be used to optimize the RPECVD process for better quality epitaxial GeSn on (0001) sapphire substrates with no buffer layer required.","PeriodicalId":13094,"journal":{"name":"IEEE Journal of Selected Topics in Quantum Electronics","volume":"31 1: SiGeSn Infrared Photon. and Quantum Electronics","pages":"1-12"},"PeriodicalIF":4.3,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142198909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-04DOI: 10.1109/JSTQE.2024.3454521
Marco Gaulke;Maximilian C. Schuchter;Nicolas Huwyler;Matthias Golling;Benjamin Willenberg;Christopher R. Phillips;Ursula Keller
Vertical emitting optically pumped semiconductor laser technology in the GaSb material system, operating in the short-wave infrared (SWIR) regime, has made significant advancements recently. This paper reviews the key achievements leading to the first demonstration of a passively modelocked optically pumped thin-disk semiconductor laser, where both the saturable absorber and the gain quantum wells are integrated into a single semiconductor chip, known as the Modelocked Integrated eXternal-cavity Surface Emitting Laser (MIXSEL). This GaSb-based MIXSEL operates at a center wavelength of 2 $rm mu$ m, supporting both single and dual-comb operations, with an average output power of 30 to 50 mW, pulse repetition rates of approximately 4 GHz, and picosecond pulse durations. It enables initial proof-of-principle dual-comb spectroscopy measurements. For this, we optimized continuous wave (cw) Vertical External Cavity Surface Emitting Laser (VECSEL) operation at 2 $rm mu$ m without an intracavity heatspreader, enhanced group delay dispersion (GDD) compensation, and introduced an additional pump mirror integration. Compared to previous results, we achieved a significant performance increase with pump-DBR 2- $rm mu$ m VECSEL with an average output power of 6 W, an optical pump efficiency of 30% and a reduced thermal resistance of 1.9 K/W. Additionally, the better GDD compensation improved modelocking at 2 $rm mu$ m with a SESAM (Semiconductor Saturable Absorber Mirror), producing near-transform-limited femtosecond pulses with a duration of 331 fs, an average power of 30 mW at a pulse repetition rate of 2.77 GHz. Successful integration of the saturable absorber within the MIXSEL chip required matching of the cavity mode sizes on both the SESAM and the VECSEL chip. This paper details the optimization processes and resulting performance enhancements that mark a significant milestone in the development of GaSb-based thin disk laser technology.
{"title":"Optically Pumped GaSb-Based Thin-Disk Laser Design Considerations for CW and Dual-Comb Operation at a Center Wavelength Around 2 $rm mu$m","authors":"Marco Gaulke;Maximilian C. Schuchter;Nicolas Huwyler;Matthias Golling;Benjamin Willenberg;Christopher R. Phillips;Ursula Keller","doi":"10.1109/JSTQE.2024.3454521","DOIUrl":"10.1109/JSTQE.2024.3454521","url":null,"abstract":"Vertical emitting optically pumped semiconductor laser technology in the GaSb material system, operating in the short-wave infrared (SWIR) regime, has made significant advancements recently. This paper reviews the key achievements leading to the first demonstration of a passively modelocked optically pumped thin-disk semiconductor laser, where both the saturable absorber and the gain quantum wells are integrated into a single semiconductor chip, known as the Modelocked Integrated eXternal-cavity Surface Emitting Laser (MIXSEL). This GaSb-based MIXSEL operates at a center wavelength of 2 \u0000<inline-formula><tex-math>$rm mu$</tex-math></inline-formula>\u0000m, supporting both single and dual-comb operations, with an average output power of 30 to 50 mW, pulse repetition rates of approximately 4 GHz, and picosecond pulse durations. It enables initial proof-of-principle dual-comb spectroscopy measurements. For this, we optimized continuous wave (cw) Vertical External Cavity Surface Emitting Laser (VECSEL) operation at 2 \u0000<inline-formula><tex-math>$rm mu$</tex-math></inline-formula>\u0000m without an intracavity heatspreader, enhanced group delay dispersion (GDD) compensation, and introduced an additional pump mirror integration. Compared to previous results, we achieved a significant performance increase with pump-DBR 2-\u0000<inline-formula><tex-math>$rm mu$</tex-math></inline-formula>\u0000m VECSEL with an average output power of 6 W, an optical pump efficiency of 30% and a reduced thermal resistance of 1.9 K/W. Additionally, the better GDD compensation improved modelocking at 2 \u0000<inline-formula><tex-math>$rm mu$</tex-math></inline-formula>\u0000m with a SESAM (Semiconductor Saturable Absorber Mirror), producing near-transform-limited femtosecond pulses with a duration of 331 fs, an average power of 30 mW at a pulse repetition rate of 2.77 GHz. Successful integration of the saturable absorber within the MIXSEL chip required matching of the cavity mode sizes on both the SESAM and the VECSEL chip. This paper details the optimization processes and resulting performance enhancements that mark a significant milestone in the development of GaSb-based thin disk laser technology.","PeriodicalId":13094,"journal":{"name":"IEEE Journal of Selected Topics in Quantum Electronics","volume":"31 2: Pwr. and Effic. Scaling in Semiconductor Lasers","pages":"1-14"},"PeriodicalIF":4.3,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10664454","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142225347","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
High-speed vertical-cavity surface-emitting lasers (VCSELs) with high single-mode (SM) output power and strong immunity to optical feedback play a vital role in further improving the package density in co-packaged optics (CPO) systems. Here, by optimizing the structure of VCSEL cavities with Zn-diffusion apertures inside, we can simultaneously improve the SM output power and speed of 850 nm VCSELs. With this novel structure we can achieve a record-high SM output power of 16 mW and a wide 3-dB electrical-to-optical (E-O) bandwidth of 18 GHz. Furthermore, excellent VCSEL performance can be obtained by varying the aperture size for high-speed operations, such as wide E-O bandwidth (27 GHz), high SM power (6.7 mW), low-RIN (−137 dB/Hz), and invariant 56 Gbps eye patterns under strong optical feedback (−6 dB). Error-free transmission can be achieved at around 48 Gbit/sec through 500 and 200 m multi-mode and single-mode fibers, respectively, without the use of equalizers in the transmission channels.
{"title":"Single-Mode VCSELs With Zn-Diffusion Apertures for Applications in Co-Packaged Optics Systems","authors":"Cheng-Wei Lin;Zhe-Wei Hsu;Jian-Wei Tung;Xin Chen;Chia-Hsuan Wang;Dong Hao;Jia-Liang Yen;J.-J. Liu;Ming-Jun Li;Jin-Wei Shi","doi":"10.1109/JSTQE.2024.3454318","DOIUrl":"10.1109/JSTQE.2024.3454318","url":null,"abstract":"High-speed vertical-cavity surface-emitting lasers (VCSELs) with high single-mode (SM) output power and strong immunity to optical feedback play a vital role in further improving the package density in co-packaged optics (CPO) systems. Here, by optimizing the structure of VCSEL cavities with Zn-diffusion apertures inside, we can simultaneously improve the SM output power and speed of 850 nm VCSELs. With this novel structure we can achieve a record-high SM output power of 16 mW and a wide 3-dB electrical-to-optical (E-O) bandwidth of 18 GHz. Furthermore, excellent VCSEL performance can be obtained by varying the aperture size for high-speed operations, such as wide E-O bandwidth (27 GHz), high SM power (6.7 mW), low-RIN (−137 dB/Hz), and invariant 56 Gbps eye patterns under strong optical feedback (−6 dB). Error-free transmission can be achieved at around 48 Gbit/sec through 500 and 200 m multi-mode and single-mode fibers, respectively, without the use of equalizers in the transmission channels.","PeriodicalId":13094,"journal":{"name":"IEEE Journal of Selected Topics in Quantum Electronics","volume":"31 2: Pwr. and Effic. Scaling in Semiconductor Lasers","pages":"1-9"},"PeriodicalIF":4.3,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142225329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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