Pub Date : 2023-12-25DOI: 10.35848/1347-4065/ad1895
Shuchao Gao, Takashi Ohsawa
We propose a novel training method named hardware-conscious software training (HCST) for deep neural network inference accelerators to recover the accuracy degradation due to their hardware imperfections. The proposed training method is totally conducted by software whose forward inference path and backpropagation reflect the hardware imperfections, overcoming the problems of the limited endurance, the nonlinearity and the asymmetry for the switching of the nonvolatile memories used in weights and biases. The HCST reformulates the mathematical expressions in the forward propagation and the gradient calculation with the backpropagation so that it replicates the hardware structure under the influence of variations in the chip fabrication process. The effectiveness of this approach is validated through the MNIST dataset experiments to manifest its capability to restore the accuracies. A circuit design is also disclosed for measuring the offset voltages and the open loop gains of the operational amplifiers used in the accelerator.
{"title":"A training method for deep neural network inference accelerators with high tolerance for their hardware imperfection","authors":"Shuchao Gao, Takashi Ohsawa","doi":"10.35848/1347-4065/ad1895","DOIUrl":"https://doi.org/10.35848/1347-4065/ad1895","url":null,"abstract":"We propose a novel training method named hardware-conscious software training (HCST) for deep neural network inference accelerators to recover the accuracy degradation due to their hardware imperfections. The proposed training method is totally conducted by software whose forward inference path and backpropagation reflect the hardware imperfections, overcoming the problems of the limited endurance, the nonlinearity and the asymmetry for the switching of the nonvolatile memories used in weights and biases. The HCST reformulates the mathematical expressions in the forward propagation and the gradient calculation with the backpropagation so that it replicates the hardware structure under the influence of variations in the chip fabrication process. The effectiveness of this approach is validated through the MNIST dataset experiments to manifest its capability to restore the accuracies. A circuit design is also disclosed for measuring the offset voltages and the open loop gains of the operational amplifiers used in the accelerator.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"12 6","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139157827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-25DOI: 10.35848/1347-4065/ad189b
Hiroya Sakumomto, Taketoshi Nakayama, Yuto Miyatake, K. Toprasertpong, Shinichi Takagi, M. Takenaka
We examine the influence of doping profile optimization on the trade-off relationship between modulation bandwidth and optical loss in an InP-organic hybrid (IOH) optical modulator, comparing it with a Si-organic hybrid (SOH) optical modulator. By incorporating the RF transmission line model, which enables a more precise modulation bandwidth analysis than the RC constant model, we demonstrate that the IOH modulator can achieve a modulation bandwidth of over 500 GHz with a 2 dB loss, capitalizing on the higher electron mobility of InP. In contrast, the SOH modulator cannot attain a 200 GHz modulation bandwidth with acceptable optical loss. Furthermore, we explore the potential for further enhancing the modulation bandwidth of the IOH modulator by shortening its length, making the IOH modulator a promising candidate for future ultra-high-speed optical modulation.
{"title":"Numerical evaluation of bandwidth and optical loss in InP-organic hybrid optical modulator with doping optimization","authors":"Hiroya Sakumomto, Taketoshi Nakayama, Yuto Miyatake, K. Toprasertpong, Shinichi Takagi, M. Takenaka","doi":"10.35848/1347-4065/ad189b","DOIUrl":"https://doi.org/10.35848/1347-4065/ad189b","url":null,"abstract":"We examine the influence of doping profile optimization on the trade-off relationship between modulation bandwidth and optical loss in an InP-organic hybrid (IOH) optical modulator, comparing it with a Si-organic hybrid (SOH) optical modulator. By incorporating the RF transmission line model, which enables a more precise modulation bandwidth analysis than the RC constant model, we demonstrate that the IOH modulator can achieve a modulation bandwidth of over 500 GHz with a 2 dB loss, capitalizing on the higher electron mobility of InP. In contrast, the SOH modulator cannot attain a 200 GHz modulation bandwidth with acceptable optical loss. Furthermore, we explore the potential for further enhancing the modulation bandwidth of the IOH modulator by shortening its length, making the IOH modulator a promising candidate for future ultra-high-speed optical modulation.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"90 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139159359","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-25DOI: 10.35848/1347-4065/ad1899
Mohd Faiz Bin Amin, Jose A. Piedra-Lorenzana, Keisuke Yamane, Takeshi Hizawa, Tetsuya Nakai, Yasuhiko Ishikawa
Threading dislocation density (TDD) in a Ge heteroepitaxial film on Si is reduced based on a dislocation trapping mechanism in a patterned substrate. An array of V-shaped grooves on the submicron scale is patterned in the [110] direction on a (001) Si substrate. An epitaxial growth of Ge with a thickness of 1 µm by chemical vapor deposition realizes a reasonable flat surface despite the non-flat starting surface. The TDD in Ge for a V-shaped groove pattern of 0.5 µm in width with the inter-groove distance of 0.3 µm is obtained as low as 4 × 107 cm–2, which is lower than about 6 × 107 cm–2 for the rectangular one with the same groove width and inter-groove distance and about 22 × 107 cm–2 for the unpatterned one. The reduction is attributed to the dislocation trapping at the groove regions, as observed by cross-sectional transmission electron microscopy.
基于图案化衬底中的位错捕获机制，降低了硅基 Ge 异向外延薄膜中的穿线位错密度 (TDD)。在(001) 硅衬底上沿[110]方向图案化了亚微米级的 V 形槽阵列。尽管起始表面并不平坦，但通过化学气相沉积，厚度为 1 µm 的 Ge 外延生长出了合理的平坦表面。在宽度为 0.5 µm、槽间距为 0.3 µm 的 V 形槽图案中，Ge 的 TDD 低至 4 × 107 cm-2，低于具有相同槽宽和槽间距的矩形图案的约 6 × 107 cm-2，也低于无图案图案的约 22 × 107 cm-2。根据横截面透射电子显微镜的观察，这一下降归因于凹槽区域的位错捕获。
{"title":"High-quality Ge epitaxial film based on dislocation trapping mechanism in patterned Si substrate","authors":"Mohd Faiz Bin Amin, Jose A. Piedra-Lorenzana, Keisuke Yamane, Takeshi Hizawa, Tetsuya Nakai, Yasuhiko Ishikawa","doi":"10.35848/1347-4065/ad1899","DOIUrl":"https://doi.org/10.35848/1347-4065/ad1899","url":null,"abstract":"Threading dislocation density (TDD) in a Ge heteroepitaxial film on Si is reduced based on a dislocation trapping mechanism in a patterned substrate. An array of V-shaped grooves on the submicron scale is patterned in the [110] direction on a (001) Si substrate. An epitaxial growth of Ge with a thickness of 1 µm by chemical vapor deposition realizes a reasonable flat surface despite the non-flat starting surface. The TDD in Ge for a V-shaped groove pattern of 0.5 µm in width with the inter-groove distance of 0.3 µm is obtained as low as 4 × 107 cm–2, which is lower than about 6 × 107 cm–2 for the rectangular one with the same groove width and inter-groove distance and about 22 × 107 cm–2 for the unpatterned one. The reduction is attributed to the dislocation trapping at the groove regions, as observed by cross-sectional transmission electron microscopy.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"41 7","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139158890","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-25DOI: 10.35848/1347-4065/ad189d
Yuji Yamamoto, Wei-Chen Wen, M. Schubert, A. A. Corley-Wiciak, Sho Sugawa, Yuta Ito, R. Yokogawa, Han Han, Roger Loo, Atsushi Ogura, Bernd Tillack
Locally dislocation-free SiGe-on-insulator(SGOI) is fabricated by chemical vapor deposition. Lateral selective SiGe growth of ~30%, ~45% and ~55% of Ge content is performed around ~1µm square Si(001) pillar located under the center of a 6.3µm square SiO2 on Si-on-insulator substrate which is formed by H2-HCl vapor-phase etching. In the deposited SiGe layer, tensile strain is observed by top-view. The degree of strain is slightly increased at the corner of the SiGe. The tensile strain is caused by the partial compressive strain of SiGe in lateral direction and thermal expansion difference between Si and SiGe. Slightly higher Ge incorporation is observed in higher tensile strain region. At the peaks formed between the facets of growth front, Ge incorporation is reduced. These phenomena are pronounced for SiGe with higher Ge contents. Locally dislocation-free SGOI, which is beneficial for emerging device integration, is formed along <010> from the Si pillar by lateral aspect-ratio-trapping.
{"title":"Thin and locally dislocation-free SiGe virtual substrate fabrication by lateral selective growth","authors":"Yuji Yamamoto, Wei-Chen Wen, M. Schubert, A. A. Corley-Wiciak, Sho Sugawa, Yuta Ito, R. Yokogawa, Han Han, Roger Loo, Atsushi Ogura, Bernd Tillack","doi":"10.35848/1347-4065/ad189d","DOIUrl":"https://doi.org/10.35848/1347-4065/ad189d","url":null,"abstract":"Locally dislocation-free SiGe-on-insulator(SGOI) is fabricated by chemical vapor deposition. Lateral selective SiGe growth of ~30%, ~45% and ~55% of Ge content is performed around ~1µm square Si(001) pillar located under the center of a 6.3µm square SiO2 on Si-on-insulator substrate which is formed by H2-HCl vapor-phase etching. In the deposited SiGe layer, tensile strain is observed by top-view. The degree of strain is slightly increased at the corner of the SiGe. The tensile strain is caused by the partial compressive strain of SiGe in lateral direction and thermal expansion difference between Si and SiGe. Slightly higher Ge incorporation is observed in higher tensile strain region. At the peaks formed between the facets of growth front, Ge incorporation is reduced. These phenomena are pronounced for SiGe with higher Ge contents. Locally dislocation-free SGOI, which is beneficial for emerging device integration, is formed along <010> from the Si pillar by lateral aspect-ratio-trapping.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"7 4","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139157617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-25DOI: 10.35848/1347-4065/ad189f
Xiang Zhou, M. Fukui, K. Takeuchi, T. Saraya, Wataru Saito, T. Hiramoto
Robustness under high temperature clamped inductive turn-off has been compared systematically among 3300V scaled Insulated Gate Bipolar Transistors (IGBTs) with scaling factor (k) from 1 to 10 by TCAD simulations. Degradation of Reverse Bias Safe Operating Area (RBSOA) has been observed in proportionally scaled IGBT, especially at high turn-off current density. Non-proportional scaling method has been proven to be able to restore the robustness degradation with RBSOA close to the original k=1 case. Moreover, the Rpf (P-floating connecting resistor) adjustment method adds more flexibility to device design, and also improves the overall electrical performance of non-proportionally scaled IGBTs. Besides, the adjustment of Rpf has been found to have minimal effect on RBSOA.
{"title":"Robust reverse bias safe operating area (RBSOA) and improved electrical performance in 3300V non-proportionally scaled insulated gate bipolar transistors (IGBTs)","authors":"Xiang Zhou, M. Fukui, K. Takeuchi, T. Saraya, Wataru Saito, T. Hiramoto","doi":"10.35848/1347-4065/ad189f","DOIUrl":"https://doi.org/10.35848/1347-4065/ad189f","url":null,"abstract":"Robustness under high temperature clamped inductive turn-off has been compared systematically among 3300V scaled Insulated Gate Bipolar Transistors (IGBTs) with scaling factor (k) from 1 to 10 by TCAD simulations. Degradation of Reverse Bias Safe Operating Area (RBSOA) has been observed in proportionally scaled IGBT, especially at high turn-off current density. Non-proportional scaling method has been proven to be able to restore the robustness degradation with RBSOA close to the original k=1 case. Moreover, the Rpf (P-floating connecting resistor) adjustment method adds more flexibility to device design, and also improves the overall electrical performance of non-proportionally scaled IGBTs. Besides, the adjustment of Rpf has been found to have minimal effect on RBSOA.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"29 5","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139158310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-25DOI: 10.35848/1347-4065/ad189a
S. Nagamizo, Hajime Tanaka, Nobuya Mori
The electronic states in 4H-SiC MOS inversion layers are theoretically analyzed using the empirical pseudopotential method (EPM). The analysis shows that the Wannier-Stark localization occurs, which is absent in an effective mass approximation (EMA). The Wannier-Stark localization modifies the electronic states in the MOS inversion layers. A model is proposed to describe the in-plane dispersion of subbands affected by the Wannier-Stark localization. The differences between the EPM and EMA results for the subband energy levels and the in-plane effective masses are discussed.
利用经验假势法（EPM）对 4H-SiC MOS 反转层中的电子态进行了理论分析。分析结果表明，出现了有效质量近似（EMA）中不存在的万尼尔-斯塔克局域化。万尼尔-斯塔克局域化改变了 MOS 反转层中的电子状态。我们提出了一个模型来描述受 Wannier-Stark 局域化影响的子带的面内色散。讨论了子带能级和面内有效质量的 EPM 和 EMA 结果之间的差异。
{"title":"Wannier-Stark localization of electronic states in 4H-SiC MOS inversion layer","authors":"S. Nagamizo, Hajime Tanaka, Nobuya Mori","doi":"10.35848/1347-4065/ad189a","DOIUrl":"https://doi.org/10.35848/1347-4065/ad189a","url":null,"abstract":"The electronic states in 4H-SiC MOS inversion layers are theoretically analyzed using the empirical pseudopotential method (EPM). The analysis shows that the Wannier-Stark localization occurs, which is absent in an effective mass approximation (EMA). The Wannier-Stark localization modifies the electronic states in the MOS inversion layers. A model is proposed to describe the in-plane dispersion of subbands affected by the Wannier-Stark localization. The differences between the EPM and EMA results for the subband energy levels and the in-plane effective masses are discussed.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"2 3","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139158510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-25DOI: 10.35848/1347-4065/ad1893
Qiaomu Zhang, Zhe Liu, Yuxin Xu, Ruihao Zhang, Hong Hou
This paper investigates the dipole-like interface states in a quasi-periodic elastic waveguide structured according to Fibonacci sequences. The dipole-like distribution arises from the interaction of different transverse modes within the waveguide. Specifically, the non-Bragg bandgap resulting from the interaction between distinct transverse modes exhibits a stronger inhibitory effect compared to the traditional Bragg bandgap. Furthermore, our simulations reveal a notable sound field distribution on the surface of the waveguide, displaying two diametrically opposite regions with maximum sound pressures. This structure, characterized by a high Q factor, provides valuable insights into designing elastic wave applications such as filtering and wave enhancement.
{"title":"Dipole-like interface states in quasi-periodic elastic waveguide based on Fibonacci sequences","authors":"Qiaomu Zhang, Zhe Liu, Yuxin Xu, Ruihao Zhang, Hong Hou","doi":"10.35848/1347-4065/ad1893","DOIUrl":"https://doi.org/10.35848/1347-4065/ad1893","url":null,"abstract":"This paper investigates the dipole-like interface states in a quasi-periodic elastic waveguide structured according to Fibonacci sequences. The dipole-like distribution arises from the interaction of different transverse modes within the waveguide. Specifically, the non-Bragg bandgap resulting from the interaction between distinct transverse modes exhibits a stronger inhibitory effect compared to the traditional Bragg bandgap. Furthermore, our simulations reveal a notable sound field distribution on the surface of the waveguide, displaying two diametrically opposite regions with maximum sound pressures. This structure, characterized by a high Q factor, provides valuable insights into designing elastic wave applications such as filtering and wave enhancement.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"39 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139159704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-25DOI: 10.35848/1347-4065/ad1894
Toshiyuki Oishi, Shiori Takada, Ken Kudara, Y. Yamaguchi, S. Shinjo, Koji Yamanaka
Drain bias dependence of Y22 and Y21 signals has been investigated by two-port network measurement at the on-state condition of AlGaN/GaN high electron mobility transistors (HEMTs). Y22 has signals for Fe-related trap in GaN layers and self-heating effect. Y21 has a unique signal otherwise than the signals with the same drain bias dependence as Y22 signals. This unique signal is considered to originate from the AlGaN trap using the device simulation with the GaN trap, AlGaN trap, and self-heating effect. The peak frequency of GaN and AlGaN traps increases as increasing the drain voltages, while the peak frequency of the self-heating doesn’t depend on the drain voltages.
{"title":"Drain bias dependence of Y22 and Y21 signals at low frequency for on-state conditions in AlGaN/GaN HEMTs","authors":"Toshiyuki Oishi, Shiori Takada, Ken Kudara, Y. Yamaguchi, S. Shinjo, Koji Yamanaka","doi":"10.35848/1347-4065/ad1894","DOIUrl":"https://doi.org/10.35848/1347-4065/ad1894","url":null,"abstract":"Drain bias dependence of Y22 and Y21 signals has been investigated by two-port network measurement at the on-state condition of AlGaN/GaN high electron mobility transistors (HEMTs). Y22 has signals for Fe-related trap in GaN layers and self-heating effect. Y21 has a unique signal otherwise than the signals with the same drain bias dependence as Y22 signals. This unique signal is considered to originate from the AlGaN trap using the device simulation with the GaN trap, AlGaN trap, and self-heating effect. The peak frequency of GaN and AlGaN traps increases as increasing the drain voltages, while the peak frequency of the self-heating doesn’t depend on the drain voltages.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"27 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139157815","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-25DOI: 10.35848/1347-4065/ad189e
Junpei Oda, Yuta Kaga, Koh Johguchi
In this study, we have developed a high-precision ultrasonic water flow meter with a 0.18 µm standard CMOS technology. Three methods are proposed to improve the performance: implementation of an active bandpass filter, threshold voltage optimization, and integration of a multi-phase time-zooming technique. The active bandpass filter effectively reduces noise in the received signal, thereby contributing to the overall accuracy of propagation measurements. Based on a threshold voltage generator, our proposed system identifies the optimum threshold voltage, ensuring robust noise durability. Furthermore, we have extended the conventional time-zooming technique by incorporating multiple phases of internal clocks. This innovative multiphase time-zooming technique offers a theoretical improvement in time resolution. The results demonstrate a remarkable suppression of flow rate measurement variations, achieving an impressive reduction to 1/10th of the original values. This affirms the effectiveness of the developed ultrasonic water flow meter in ensuring precise and reliable flow rate measurements.
{"title":"A multi-phase time-zooming high-precision ultrasonic water flow meter","authors":"Junpei Oda, Yuta Kaga, Koh Johguchi","doi":"10.35848/1347-4065/ad189e","DOIUrl":"https://doi.org/10.35848/1347-4065/ad189e","url":null,"abstract":"In this study, we have developed a high-precision ultrasonic water flow meter with a 0.18 µm standard CMOS technology. Three methods are proposed to improve the performance: implementation of an active bandpass filter, threshold voltage optimization, and integration of a multi-phase time-zooming technique. The active bandpass filter effectively reduces noise in the received signal, thereby contributing to the overall accuracy of propagation measurements. Based on a threshold voltage generator, our proposed system identifies the optimum threshold voltage, ensuring robust noise durability. Furthermore, we have extended the conventional time-zooming technique by incorporating multiple phases of internal clocks. This innovative multiphase time-zooming technique offers a theoretical improvement in time resolution. The results demonstrate a remarkable suppression of flow rate measurement variations, achieving an impressive reduction to 1/10th of the original values. This affirms the effectiveness of the developed ultrasonic water flow meter in ensuring precise and reliable flow rate measurements.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139159554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-25DOI: 10.35848/1347-4065/ad18a0
Zhiwei Dai, Wenbo Lin, Satoshi Iwamoto
Ring resonators are traditionally popular optical devices that apply to various components in photonic integrated circuits. They also play an important role in the on-chip generation of many novel optical states in topological systems and non-Hermitian systems. Unidirectional lasing of ring resonators is used in many such systems to create exotic states of light including optical vortexes and optical skyrmions, but the unidirectional behavior has not been fully understood. Previous research has constructed a simplified model to explain the steady state behaviors of unidirectional ring resonators, but the carrier dynamics and spontaneous emission were omitted. In this work, we give a numerical analysis of unidirectional ring resonators with an S-shaped coupler. We identified the importance of the gain saturation to robustness against backscattering and high unidirectionality by comparing to the linear model without saturation. We also discuss the effect of amount of asymmetrical coupling to the realization of unidirectionality.
环形谐振器是一种传统的流行光学设备，适用于光子集成电路中的各种组件。在拓扑系统和非赫米提系统中，环形谐振器在片上产生许多新颖的光学状态方面也发挥着重要作用。在许多此类系统中，环形谐振器的单向激光被用来产生奇异的光状态，包括光涡旋和光天幕，但人们对其单向行为尚未完全了解。以往的研究构建了一个简化模型来解释单向环形谐振器的稳态行为，但忽略了载流子动力学和自发辐射。在这项研究中，我们对带有 S 形耦合器的单向环形谐振器进行了数值分析。通过与无饱和的线性模型进行比较，我们确定了增益饱和对抗反向散射和高单向性的重要性。我们还讨论了非对称耦合量对实现单向性的影响。
{"title":"Rate equation analysis for deterministic and unidirectional lasing in ring resonators with an S-shaped coupler","authors":"Zhiwei Dai, Wenbo Lin, Satoshi Iwamoto","doi":"10.35848/1347-4065/ad18a0","DOIUrl":"https://doi.org/10.35848/1347-4065/ad18a0","url":null,"abstract":"Ring resonators are traditionally popular optical devices that apply to various components in photonic integrated circuits. They also play an important role in the on-chip generation of many novel optical states in topological systems and non-Hermitian systems. Unidirectional lasing of ring resonators is used in many such systems to create exotic states of light including optical vortexes and optical skyrmions, but the unidirectional behavior has not been fully understood. Previous research has constructed a simplified model to explain the steady state behaviors of unidirectional ring resonators, but the carrier dynamics and spontaneous emission were omitted. In this work, we give a numerical analysis of unidirectional ring resonators with an S-shaped coupler. We identified the importance of the gain saturation to robustness against backscattering and high unidirectionality by comparing to the linear model without saturation. We also discuss the effect of amount of asymmetrical coupling to the realization of unidirectionality.","PeriodicalId":14741,"journal":{"name":"Japanese Journal of Applied Physics","volume":"19 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2023-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139158907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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