Pub Date : 2023-01-01DOI: 10.3788/col202321.090002
Can Li, Yue Tao, Man Jiang, P. Ma, W. Liu, R. Su, Jiangming Xu, Jin-yong Leng, P. Zhou
Unlike conventional continuous-wave lasers with wide spectra, the amplification of single-frequency lasers in optical fibers is much more difficult owing to the ultra-high power spectral density induced nonlinear stimulated Brillouin scattering effect. Nevertheless, over the past two decades much effort has been devoted to improving the power scaling and performance of high-power single-frequency fiber amplifiers. These amplifiers are mostly driven by applications, such as high precision detection and metrology, and have benefited from the long coherence length, low noise, and excellent beam quality of this type of laser source. In this paper, we review the overall development of high-power single-frequency fiber amplifiers by focusing on its progress and challenges, specifically, the strategies for circumventing the stimulated Brillouin scattering and transverse mode instability effects that, at present, are the major limiting factors of the power scaling of the single-frequency fiber amplifiers. These factors are also thoroughly discussed in terms of free-space and all-fiber coupled architecture. In addition, we also examine the noise properties of single-frequency fiber amplifiers, along with corresponding noise reducing schemes. Finally, we briefly envision the future development of high-power single-frequency fiber amplifiers.
{"title":"High-power single-frequency fiber amplifiers: progress and challenge [Invited]","authors":"Can Li, Yue Tao, Man Jiang, P. Ma, W. Liu, R. Su, Jiangming Xu, Jin-yong Leng, P. Zhou","doi":"10.3788/col202321.090002","DOIUrl":"https://doi.org/10.3788/col202321.090002","url":null,"abstract":"Unlike conventional continuous-wave lasers with wide spectra, the amplification of single-frequency lasers in optical fibers is much more difficult owing to the ultra-high power spectral density induced nonlinear stimulated Brillouin scattering effect. Nevertheless, over the past two decades much effort has been devoted to improving the power scaling and performance of high-power single-frequency fiber amplifiers. These amplifiers are mostly driven by applications, such as high precision detection and metrology, and have benefited from the long coherence length, low noise, and excellent beam quality of this type of laser source. In this paper, we review the overall development of high-power single-frequency fiber amplifiers by focusing on its progress and challenges, specifically, the strategies for circumventing the stimulated Brillouin scattering and transverse mode instability effects that, at present, are the major limiting factors of the power scaling of the single-frequency fiber amplifiers. These factors are also thoroughly discussed in terms of free-space and all-fiber coupled architecture. In addition, we also examine the noise properties of single-frequency fiber amplifiers, along with corresponding noise reducing schemes. Finally, we briefly envision the future development of high-power single-frequency fiber amplifiers.","PeriodicalId":10293,"journal":{"name":"Chinese Optics Letters","volume":"7 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82628703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2023-01-01DOI: 10.3788/col202321.041203
Jingtao Dong, Tengda Zhang, Lei Yang, Yuzhong Zhang, R. Lu, Xinglong Xie
{"title":"Dark-field line confocal imaging with point confocality and extended line field for bulk defects detection","authors":"Jingtao Dong, Tengda Zhang, Lei Yang, Yuzhong Zhang, R. Lu, Xinglong Xie","doi":"10.3788/col202321.041203","DOIUrl":"https://doi.org/10.3788/col202321.041203","url":null,"abstract":"","PeriodicalId":10293,"journal":{"name":"Chinese Optics Letters","volume":"4 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87797767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2023-01-01DOI: 10.3788/col202321.051201
Fan Zhang, Beibei Qi, Baijin Su, Ou Xu, Yuwen Qin
{"title":"High sensitivity all-fiber bend sensor based on modal interferences in a ring core fiber","authors":"Fan Zhang, Beibei Qi, Baijin Su, Ou Xu, Yuwen Qin","doi":"10.3788/col202321.051201","DOIUrl":"https://doi.org/10.3788/col202321.051201","url":null,"abstract":"","PeriodicalId":10293,"journal":{"name":"Chinese Optics Letters","volume":"11 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88119011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
The temporal coupled-mode theory (TCMT) has made significant progress in recent years, and is widely applied in explaining a variety of optical phenomena. In this paper, the optical characteristics of the metasurface composed of nano-bars and nano-rings are simulated. The simulation results are well explained by TCMT under the coupled basis vector. However, when the structural asymmetry is large, the fitting of results shows that the total radiation loss is not conservative, in contradiction to the requirement of traditional TCMT. We solved this inconsistency by introducing the propagation phase into the near-field coupling term of TCMT. The studies show that, unlike the local mode near the exceptional point which corresponds to the radiation loss of the bright mode, the global mode near the diabolic point is closely related to the propagation phase. Furthermore, the structure near the diabolic point shows characteristic cross-coupling with the change of period. This study proposes a new theoretical framework for comprehending the interaction of light and matter and offers some guiding implications for the application of TCMT to a variety of related domains.
{"title":"Effects of propagation phase on the coupling of plasmonic optical modes","authors":"Wan-xia Huang, Yabo Zhang, Yuan Pei, Maosheng Wang, Fenghua Shi, Kuan-Yi Li","doi":"10.3788/col202321.010003","DOIUrl":"https://doi.org/10.3788/col202321.010003","url":null,"abstract":"The temporal coupled-mode theory (TCMT) has made significant progress in recent years, and is widely applied in explaining a variety of optical phenomena. In this paper, the optical characteristics of the metasurface composed of nano-bars and nano-rings are simulated. The simulation results are well explained by TCMT under the coupled basis vector. However, when the structural asymmetry is large, the fitting of results shows that the total radiation loss is not conservative, in contradiction to the requirement of traditional TCMT. We solved this inconsistency by introducing the propagation phase into the near-field coupling term of TCMT. The studies show that, unlike the local mode near the exceptional point which corresponds to the radiation loss of the bright mode, the global mode near the diabolic point is closely related to the propagation phase. Furthermore, the structure near the diabolic point shows characteristic cross-coupling with the change of period. This study proposes a new theoretical framework for comprehending the interaction of light and matter and offers some guiding implications for the application of TCMT to a variety of related domains.","PeriodicalId":10293,"journal":{"name":"Chinese Optics Letters","volume":"32 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81275922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2023-01-01DOI: 10.3788/col202321.112601
Peihua Jie, Zhenwei Xie, Xiaocong Yuan
A new type of power-exponent-phase vortex-like beams with both quadratic and cubic azimuthal phase gradients is investigated in this work. The intensity and orbital angular momentum (OAM) density distributions are noticeably different when the phase gradient increases or decreases along the azimuth angle, while the orthogonality and total OAM remain constant. The characteristics of the optical field undergo a significant change when the phase shifts from linear to nonlinear, with the variation of the power index having little impact on the beam characteristics under nonlinear phase conditions. These characteristics provide new ideas for applications such as particle manipulation, optical communications, and OAM encryption.
{"title":"Optical spiral vortex from azimuthally increasing/decreasing exponential phase gradients","authors":"Peihua Jie, Zhenwei Xie, Xiaocong Yuan","doi":"10.3788/col202321.112601","DOIUrl":"https://doi.org/10.3788/col202321.112601","url":null,"abstract":"A new type of power-exponent-phase vortex-like beams with both quadratic and cubic azimuthal phase gradients is investigated in this work. The intensity and orbital angular momentum (OAM) density distributions are noticeably different when the phase gradient increases or decreases along the azimuth angle, while the orthogonality and total OAM remain constant. The characteristics of the optical field undergo a significant change when the phase shifts from linear to nonlinear, with the variation of the power index having little impact on the beam characteristics under nonlinear phase conditions. These characteristics provide new ideas for applications such as particle manipulation, optical communications, and OAM encryption.","PeriodicalId":10293,"journal":{"name":"Chinese Optics Letters","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135612370","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2023-01-01DOI: 10.3788/col202321.111201
An Ye, Dingyuan Fu, Mingming Wu, Jiahao Guo, Tianze Sheng, Xiaolin Li, Shangqing Gong, Yueping Niu
Nitrogen-vacancy (NV) centers in diamond are progressively favored for room-temperature magnetic field measurement. The signal to noise ratio (SNR) optimization for NV diamond magnetometry generally concentrates on signal amplitude enhancement rather than efficient noise processing. Here, we report a compound filter system combining a wavelet denoising method and an adaptive filter for the realization of an efficient weak magnetic measurement with a high SNR. It allows enhanced magnetic field measurement with an average SNR enhancement of 17.80 dB at 50 nT within 500 mHz to 100 Hz and 14.76 dB at 500 mHz within 50 nT to 1100 nT. The introduction of this system in NV diamond magnetometry is aimed to improve signal quality by effectively eliminating the noise and retaining ideal signals.
{"title":"SNR enhancement of magnetic fields measurement with the diamond NV center using a compound filter system","authors":"An Ye, Dingyuan Fu, Mingming Wu, Jiahao Guo, Tianze Sheng, Xiaolin Li, Shangqing Gong, Yueping Niu","doi":"10.3788/col202321.111201","DOIUrl":"https://doi.org/10.3788/col202321.111201","url":null,"abstract":"Nitrogen-vacancy (NV) centers in diamond are progressively favored for room-temperature magnetic field measurement. The signal to noise ratio (SNR) optimization for NV diamond magnetometry generally concentrates on signal amplitude enhancement rather than efficient noise processing. Here, we report a compound filter system combining a wavelet denoising method and an adaptive filter for the realization of an efficient weak magnetic measurement with a high SNR. It allows enhanced magnetic field measurement with an average SNR enhancement of 17.80 dB at 50 nT within 500 mHz to 100 Hz and 14.76 dB at 500 mHz within 50 nT to 1100 nT. The introduction of this system in NV diamond magnetometry is aimed to improve signal quality by effectively eliminating the noise and retaining ideal signals.","PeriodicalId":10293,"journal":{"name":"Chinese Optics Letters","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135612372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
The distribution of metal nanoparticles on the surface of a surface enhancement Raman scattering (SERS)-active substrate plays a prominent part in not only the enhancement of Raman vibration signal, but also the spectrum uniformity. Here, a facile method to fabricate SERS substrates with excellent homogeneity and low cost was proposed, in which a lyotropic liquid crystal soft template was introduced for the coordinated growth of the silver nanoflowers in the process of electrochemistry deposition. Simulation was carried out to illustrate the dominated influence of the distance of electrodes on the deposited nanoparticle number. Two kinds of conductive materials, silver plate and indium tin oxide (ITO) glass, were chosen as the anode, while the cathode was fixed as ITO glass. The simulated conjecture on the effect of electrode flatness on the uniformity of deposited nanoparticles in silver is experimentally proved. More importantly, it was demonstrated that with a relatively smooth and flat ITO glass anode, a SERS substrate featuring higher spectrum uniformity could be achieved. This work is of great significance to the actual applications of the SERS substrate for quantitative detection with high sensitivity.
{"title":"Improvement of Raman spectrum uniformity of SERS substrate based on flat electrode","authors":"Zhihui Jiang, Shen Zhang, Congxi Song, Hongmin Mao, Xin Zhao, Huanjun Lu, Zhaoliang Cao","doi":"10.3788/col202321.113001","DOIUrl":"https://doi.org/10.3788/col202321.113001","url":null,"abstract":"The distribution of metal nanoparticles on the surface of a surface enhancement Raman scattering (SERS)-active substrate plays a prominent part in not only the enhancement of Raman vibration signal, but also the spectrum uniformity. Here, a facile method to fabricate SERS substrates with excellent homogeneity and low cost was proposed, in which a lyotropic liquid crystal soft template was introduced for the coordinated growth of the silver nanoflowers in the process of electrochemistry deposition. Simulation was carried out to illustrate the dominated influence of the distance of electrodes on the deposited nanoparticle number. Two kinds of conductive materials, silver plate and indium tin oxide (ITO) glass, were chosen as the anode, while the cathode was fixed as ITO glass. The simulated conjecture on the effect of electrode flatness on the uniformity of deposited nanoparticles in silver is experimentally proved. More importantly, it was demonstrated that with a relatively smooth and flat ITO glass anode, a SERS substrate featuring higher spectrum uniformity could be achieved. This work is of great significance to the actual applications of the SERS substrate for quantitative detection with high sensitivity.","PeriodicalId":10293,"journal":{"name":"Chinese Optics Letters","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135612381","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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}
The nonlinear physics dynamics of temporal dissipative solitons in a microcavity hinder them from attaining high power from pump lasers with a typical nonlinear energy conversion efficiency of less than 1%. Here, we experimentally demonstrate a straightforward method for improving the output power of soliton combs using a silica microrod cavity with high coupling strength, large mode volume, and high-Q factor, resulting in a low-repetition-rate dissipative soliton ( ∼ 21 GHz) with an energy conversion efficiency exceeding 20%. Furthermore, by generating an ∼ 105 GHz 5 × FSR (free spectral range) soliton crystal comb in the microcavity, the energy conversion efficiency can be further increased up to 56%.
{"title":"High energy efficiency soliton microcomb generation in high coupling strength, large mode volume, and ultra-high-Q micro-cavity","authors":"Wenwen Cui, Zheng Yi, Xinyu Ma, Yong Geng, Heng Zhou, Kun Qiu","doi":"10.3788/col202321.101902","DOIUrl":"https://doi.org/10.3788/col202321.101902","url":null,"abstract":"The nonlinear physics dynamics of temporal dissipative solitons in a microcavity hinder them from attaining high power from pump lasers with a typical nonlinear energy conversion efficiency of less than 1%. Here, we experimentally demonstrate a straightforward method for improving the output power of soliton combs using a silica microrod cavity with high coupling strength, large mode volume, and high-Q factor, resulting in a low-repetition-rate dissipative soliton ( ∼ 21 GHz) with an energy conversion efficiency exceeding 20%. Furthermore, by generating an ∼ 105 GHz 5 × FSR (free spectral range) soliton crystal comb in the microcavity, the energy conversion efficiency can be further increased up to 56%.","PeriodicalId":10293,"journal":{"name":"Chinese Optics Letters","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136206802","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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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