Pub Date : 2023-12-21DOI: 10.3390/photonics11010006
Andreas Hoffmann, J. Good, M. Gross, M. Krasilnikov, Frank Stephan
A key issue of X-ray free-electron lasers is the quality of the photoelectron beams generated from a photocathode by laser pulses in the high-gradient RF gun. Controlling the shape of these laser pulses can strongly reduce the transverse emittance of the generated electron bunch. For this purpose, a laser pulseshaper at 515 nm is presented that can be used directly with alkali antimonide photocathodes for photoemission. The first results regarding generation and measurement of flattop and parabolic pulses as well as introduction of modulations for THz generation are presented and show the potential for emittance optimization with 3D ellipsoidal pulses with the proposed pulseshaper. The experiments are carried out for Cs2Te photocathodes, which require second harmonic generation of the shaped pulses and thus allow investigation of pulseshape preservation in nonlinear frequency conversion processes.
X 射线自由电子激光器的一个关键问题是高梯度射频枪中的激光脉冲从光电阴极产生的光电子束的质量。控制这些激光脉冲的形状可以大大降低所产生的电子束的横向幅射。为此，我们介绍了一种波长为 515 nm 的激光脉冲整形器，它可以直接用于碱锑化物光电阴极的光发射。本文介绍了有关平顶和抛物面脉冲的产生和测量以及太赫兹产生调制的初步结果，并展示了利用所建议的脉冲整形器进行三维椭圆形脉冲发射率优化的潜力。实验是针对 Cs2Te 光电阴极进行的，它需要二次谐波产生成型脉冲，因此可以研究非线性频率转换过程中的脉冲形状保持。
{"title":"Towards Implementation of 3D Amplitude Shaping at 515 nm and First Pulseshaping Experiments at PITZ","authors":"Andreas Hoffmann, J. Good, M. Gross, M. Krasilnikov, Frank Stephan","doi":"10.3390/photonics11010006","DOIUrl":"https://doi.org/10.3390/photonics11010006","url":null,"abstract":"A key issue of X-ray free-electron lasers is the quality of the photoelectron beams generated from a photocathode by laser pulses in the high-gradient RF gun. Controlling the shape of these laser pulses can strongly reduce the transverse emittance of the generated electron bunch. For this purpose, a laser pulseshaper at 515 nm is presented that can be used directly with alkali antimonide photocathodes for photoemission. The first results regarding generation and measurement of flattop and parabolic pulses as well as introduction of modulations for THz generation are presented and show the potential for emittance optimization with 3D ellipsoidal pulses with the proposed pulseshaper. The experiments are carried out for Cs2Te photocathodes, which require second harmonic generation of the shaped pulses and thus allow investigation of pulseshape preservation in nonlinear frequency conversion processes.","PeriodicalId":20154,"journal":{"name":"Photonics","volume":"55 3","pages":""},"PeriodicalIF":2.4,"publicationDate":"2023-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138948665","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 : 2023-12-20DOI: 10.3390/photonics11010003
Debanuj Chatterjee, Sugeet Sunder, Mrudula Krishna, Suchita Yadav, Alexej Sysoliatin, Konstantin Gochelashvili, Sergey Semjonov, D. Venkitesh, Andrey Konyukhov
Fiber optic parametric and phase sensitive amplifiers (PSA) are interesting for modern day communication technologies due to their low noise and high gain amplification properties with a potential for all optical signal processing and wide band operation. PSAs are typically employed in either a single pump or dual pump configuration. In this article we explore the utilities of both configurations, however considering a fiber with a longitudinally varying dispersion profile. For the single pump case, PSA operation at large pump-signal detunings, that arise due to the longitudinal dispersion variation, were studied numerically, and recipes of using the system as a wide band wavelength selective filter were laid out. For the dual-pump case, emphasis was laid on achieving a larger signal gain, by reducing stimulated Brillouin scattering (SBS) that prevents large pump power transport through the nonlinear fiber. First, the effects of dispersion variation on the gain of a dual pump PSA were studied analytically and numerically in order to optimize the dispersion variation profile, neglecting SBS processes. Then we independently studied the SBS dynamics of the system numerically. A sinusoidally dispersion oscillating fiber (DOF) was found to be an optimal candidate with respect to its PSA and SBS performances. To establish this claim, we also experimentally compared the performance of an available DOF over a standard highly nonlinear fiber (HNLF) that has a constant dispersion profile and established its utility for designing a high gain PSA system, thanks to the SBS mitigation due to the longitudinal dispersion variation of the fiber.
光纤参量和相敏放大器（PSA）具有低噪声和高增益放大特性，可用于全光信号处理和宽带操作，因此对现代通信技术很有吸引力。PSA 通常采用单泵浦或双泵浦配置。在本文中，我们将探讨这两种配置的实用性，但考虑到光纤具有纵向变化的色散曲线。在单泵情况下，我们对由于纵向色散变化而产生的大泵信号失谐情况下的 PSA 运行进行了数值研究，并提出了将该系统用作宽带波长选择滤波器的方法。在双泵情况下，重点是通过减少受激布里渊散射（SBS）来实现更大的信号增益，因为这种散射会阻碍大泵功率通过非线性光纤的传输。首先，我们对色散变化对双泵 PSA 增益的影响进行了分析和数值研究，以便在忽略 SBS 过程的情况下优化色散变化曲线。然后，我们对系统的 SBS 动态进行了独立的数值研究。结果发现，正弦色散振荡光纤（DOF）是 PSA 和 SBS 性能的最佳候选者。为了证实这一点，我们还在实验中比较了具有恒定色散曲线的标准高非线性光纤（HNLF）与现有 DOF 的性能，并确定了其在设计高增益 PSA 系统方面的实用性，这要归功于光纤纵向色散变化所带来的 SBS 缓解效果。
{"title":"A Comprehensive Study on Phase Sensitive Amplification and Stimulated Brillouin Scattering in Nonlinear Fibers with Longitudinally Varying Dispersion","authors":"Debanuj Chatterjee, Sugeet Sunder, Mrudula Krishna, Suchita Yadav, Alexej Sysoliatin, Konstantin Gochelashvili, Sergey Semjonov, D. Venkitesh, Andrey Konyukhov","doi":"10.3390/photonics11010003","DOIUrl":"https://doi.org/10.3390/photonics11010003","url":null,"abstract":"Fiber optic parametric and phase sensitive amplifiers (PSA) are interesting for modern day communication technologies due to their low noise and high gain amplification properties with a potential for all optical signal processing and wide band operation. PSAs are typically employed in either a single pump or dual pump configuration. In this article we explore the utilities of both configurations, however considering a fiber with a longitudinally varying dispersion profile. For the single pump case, PSA operation at large pump-signal detunings, that arise due to the longitudinal dispersion variation, were studied numerically, and recipes of using the system as a wide band wavelength selective filter were laid out. For the dual-pump case, emphasis was laid on achieving a larger signal gain, by reducing stimulated Brillouin scattering (SBS) that prevents large pump power transport through the nonlinear fiber. First, the effects of dispersion variation on the gain of a dual pump PSA were studied analytically and numerically in order to optimize the dispersion variation profile, neglecting SBS processes. Then we independently studied the SBS dynamics of the system numerically. A sinusoidally dispersion oscillating fiber (DOF) was found to be an optimal candidate with respect to its PSA and SBS performances. To establish this claim, we also experimentally compared the performance of an available DOF over a standard highly nonlinear fiber (HNLF) that has a constant dispersion profile and established its utility for designing a high gain PSA system, thanks to the SBS mitigation due to the longitudinal dispersion variation of the fiber.","PeriodicalId":20154,"journal":{"name":"Photonics","volume":"82 10","pages":""},"PeriodicalIF":2.4,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138956818","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}
To improve the low responsivity of the silicon avalanche photodiode in the near-ultraviolet wavelength range, we designed a near-ultraviolet highly responsive Si-APD basic structure with a multiplication layer neighboring the photosensitive surface through the analysis of the optical absorption characteristics, junction breakdown characteristics, and avalanche multiplication characteristics. The dark current and electric field distribution of the device were investigated. Meanwhile, the structural parameters of the surface non-depleted layer, multiplication layer, and absorption layer were optimized. It was found that the breakdown voltage of the device is 21.07 V. At an applied bias voltage of 20.02 V, the device exhibits a responsivity of 6.79–14.51 A/W in the wavelength range of 300–400 nm. These results provide valuable insights for the design of silicon avalanche photodiode with high responsivity in the near-ultraviolet range.
{"title":"Research on the Structure Design of Silicon Avalanche Photodiode with Near-Ultraviolet High Responsivity","authors":"Guangtong Guo, Wei Chen, Kaifeng Zheng, Jinguang Lv, Yuxin Qin, Baixuan Zhao, Yingze Zhao, Yupeng Chen, Dan-ning Gao, Jingqiu Liang, Weibiao Wang","doi":"10.3390/photonics11010001","DOIUrl":"https://doi.org/10.3390/photonics11010001","url":null,"abstract":"To improve the low responsivity of the silicon avalanche photodiode in the near-ultraviolet wavelength range, we designed a near-ultraviolet highly responsive Si-APD basic structure with a multiplication layer neighboring the photosensitive surface through the analysis of the optical absorption characteristics, junction breakdown characteristics, and avalanche multiplication characteristics. The dark current and electric field distribution of the device were investigated. Meanwhile, the structural parameters of the surface non-depleted layer, multiplication layer, and absorption layer were optimized. It was found that the breakdown voltage of the device is 21.07 V. At an applied bias voltage of 20.02 V, the device exhibits a responsivity of 6.79–14.51 A/W in the wavelength range of 300–400 nm. These results provide valuable insights for the design of silicon avalanche photodiode with high responsivity in the near-ultraviolet range.","PeriodicalId":20154,"journal":{"name":"Photonics","volume":" 6","pages":""},"PeriodicalIF":2.4,"publicationDate":"2023-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138962669","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 : 2023-12-19DOI: 10.3390/photonics11010002
I. Vatnik, Oleg A. Gorbunov, Dmitry V. Churkin
We present a new design of a random Raman fiber laser based on a graded-index multimode fiber as the media composing the cavity that allows the generation of narrow spectral lines. We carried out spectral measurements using an optical heterodyning technique by projecting multimode radiation onto the fundamental mode of a standard single-mode fiber. The measurements confirmed the presence of localized ultra-narrow short-lived modes. We measured the powers of the modes and found it to be significantly higher (up to 25 mW) compared with those in a random Raman laser based on a single-mode fiber (<2 mW), while preserving the same typical lifetimes of a few milliseconds.
{"title":"Generation of Narrow Modes in Random Raman Fiber Laser Based on Multimode Fiber","authors":"I. Vatnik, Oleg A. Gorbunov, Dmitry V. Churkin","doi":"10.3390/photonics11010002","DOIUrl":"https://doi.org/10.3390/photonics11010002","url":null,"abstract":"We present a new design of a random Raman fiber laser based on a graded-index multimode fiber as the media composing the cavity that allows the generation of narrow spectral lines. We carried out spectral measurements using an optical heterodyning technique by projecting multimode radiation onto the fundamental mode of a standard single-mode fiber. The measurements confirmed the presence of localized ultra-narrow short-lived modes. We measured the powers of the modes and found it to be significantly higher (up to 25 mW) compared with those in a random Raman laser based on a single-mode fiber (<2 mW), while preserving the same typical lifetimes of a few milliseconds.","PeriodicalId":20154,"journal":{"name":"Photonics","volume":" 19","pages":""},"PeriodicalIF":2.4,"publicationDate":"2023-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138961659","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 : 2023-12-18DOI: 10.3390/photonics10121389
Vladimir Kamynin, Vitalii V. Kashin, Dmitri A. Nikolaev, A. Trikshev, Vladimir B. Tsvetkov
The output spectral, temporal, and spatial parameters of a two-channel Yb-fiber laser operating in an incoherent intracavity spectral beam-combining mode were investigated. One of the laser channels operated in continuous pumping mode, and the second channel operated in pulse-periodic pumping mode with a pulse duration of microseconds. When the channels operated separately, continuous lasing at a wavelength of λ1 was observed in one channel, and pulsed lasing at a wavelength of λ2 was observed in the other. When both channels operated simultaneously, it was shown that during the pump pulse action, the laser switched operation to pulsed collective mode lasing at a wavelength of (λ1 + λ2)/2. Lasing at wavelengths λ1 and λ2 was not observed at this time.
{"title":"A Laser with Intracavity Spectral Beam Combining with Continuous-Wave and Pulse-Periodic Pumping of Various Lasing Channels","authors":"Vladimir Kamynin, Vitalii V. Kashin, Dmitri A. Nikolaev, A. Trikshev, Vladimir B. Tsvetkov","doi":"10.3390/photonics10121389","DOIUrl":"https://doi.org/10.3390/photonics10121389","url":null,"abstract":"The output spectral, temporal, and spatial parameters of a two-channel Yb-fiber laser operating in an incoherent intracavity spectral beam-combining mode were investigated. One of the laser channels operated in continuous pumping mode, and the second channel operated in pulse-periodic pumping mode with a pulse duration of microseconds. When the channels operated separately, continuous lasing at a wavelength of λ1 was observed in one channel, and pulsed lasing at a wavelength of λ2 was observed in the other. When both channels operated simultaneously, it was shown that during the pump pulse action, the laser switched operation to pulsed collective mode lasing at a wavelength of (λ1 + λ2)/2. Lasing at wavelengths λ1 and λ2 was not observed at this time.","PeriodicalId":20154,"journal":{"name":"Photonics","volume":"32 5","pages":""},"PeriodicalIF":2.4,"publicationDate":"2023-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139175907","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 : 2023-12-18DOI: 10.3390/photonics10121391
N. V. Rudakova, Rashid G. Bikbaev, Larisa E. Tyryshkina, Stepan Ya. Vetrov, I. Timofeev
The circular polarization of light flips its handedness after a conventional metallic mirror reflection. Therefore, a polarization-preserving metasurface is a crucially important element in a series of chiral photonic structures. They include tunable cholesteric LCs and anisotropic photonic crystals. Chiral structures are rich in interfacial localized modes including Tamm states. In this report, coupled modes formed as a result of the interaction between two chiral optical Tamm states or a chiral optical Tamm state and a chiral Tamm plasmon polariton are analytically and numerically investigated. It is shown that the effective control of coupled modes can be carried out by changing the pitch of the cholesteric and the angle between the optical axis of the cholesteric and the polarization-preserving anisotropic mirror. The influence of the metasurface period on the spectral characteristics of coupled modes is investigated. The possibility of realizing a bound state in the continuum of the Friedrich–Wintgen type, resulting from the destructive interference of coupled modes, which leads to the collapse of the resonance line corresponding to the chiral optical Tamm state, has been demonstrated.
{"title":"Tuning Q-Factor and Perfect Absorption Using Coupled Tamm States on Polarization-Preserving Metasurface","authors":"N. V. Rudakova, Rashid G. Bikbaev, Larisa E. Tyryshkina, Stepan Ya. Vetrov, I. Timofeev","doi":"10.3390/photonics10121391","DOIUrl":"https://doi.org/10.3390/photonics10121391","url":null,"abstract":"The circular polarization of light flips its handedness after a conventional metallic mirror reflection. Therefore, a polarization-preserving metasurface is a crucially important element in a series of chiral photonic structures. They include tunable cholesteric LCs and anisotropic photonic crystals. Chiral structures are rich in interfacial localized modes including Tamm states. In this report, coupled modes formed as a result of the interaction between two chiral optical Tamm states or a chiral optical Tamm state and a chiral Tamm plasmon polariton are analytically and numerically investigated. It is shown that the effective control of coupled modes can be carried out by changing the pitch of the cholesteric and the angle between the optical axis of the cholesteric and the polarization-preserving anisotropic mirror. The influence of the metasurface period on the spectral characteristics of coupled modes is investigated. The possibility of realizing a bound state in the continuum of the Friedrich–Wintgen type, resulting from the destructive interference of coupled modes, which leads to the collapse of the resonance line corresponding to the chiral optical Tamm state, has been demonstrated.","PeriodicalId":20154,"journal":{"name":"Photonics","volume":"11 3","pages":""},"PeriodicalIF":2.4,"publicationDate":"2023-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139175974","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 : 2023-12-18DOI: 10.3390/photonics10121388
Weidong Zhang, Lulu Wang, Xiaying Wu, Li Fei, Han Peng, Ke Wen, Yanli Zhao
The maximum ratio combining (MRC) diversity technology has shown outstanding performance in overcoming the adverse effects of underwater wireless optical communication (UWOC) systems. However, its actual performance gain will be affected by the detection area and noise, which requires an in-depth analysis. In this paper, on the basis of fully considering the noises in the UWOC system, the performance of the MRC diversity technology is fairly and comprehensively studied by comparing it with two single-input–single-output (SISO) systems using a small aperture detection (SAD) scheme or a large-aperture detection (LAD) scheme through a Monte Carlo simulation and a formula analysis. The results show that the traditional belief that the MRC diversity scheme has consistently outperformed SISO systems may be misleading. When the thermal noise is dominant and the background noise is small, the LAD scheme performs better than the MRC diversity scheme with the same detection area. And in other cases, the MRC diversity scheme with the same detection area is always superior to the SISO systems. The conclusions obtained in this paper have a guiding significance for the practical application of UWOC.
{"title":"Performance Evaluation of Maximum Ratio Combining Diversity Technology and Traditional System Based on Comprehensive Noise Analysis in Underwater Wireless Optical Communication","authors":"Weidong Zhang, Lulu Wang, Xiaying Wu, Li Fei, Han Peng, Ke Wen, Yanli Zhao","doi":"10.3390/photonics10121388","DOIUrl":"https://doi.org/10.3390/photonics10121388","url":null,"abstract":"The maximum ratio combining (MRC) diversity technology has shown outstanding performance in overcoming the adverse effects of underwater wireless optical communication (UWOC) systems. However, its actual performance gain will be affected by the detection area and noise, which requires an in-depth analysis. In this paper, on the basis of fully considering the noises in the UWOC system, the performance of the MRC diversity technology is fairly and comprehensively studied by comparing it with two single-input–single-output (SISO) systems using a small aperture detection (SAD) scheme or a large-aperture detection (LAD) scheme through a Monte Carlo simulation and a formula analysis. The results show that the traditional belief that the MRC diversity scheme has consistently outperformed SISO systems may be misleading. When the thermal noise is dominant and the background noise is small, the LAD scheme performs better than the MRC diversity scheme with the same detection area. And in other cases, the MRC diversity scheme with the same detection area is always superior to the SISO systems. The conclusions obtained in this paper have a guiding significance for the practical application of UWOC.","PeriodicalId":20154,"journal":{"name":"Photonics","volume":"81 ","pages":""},"PeriodicalIF":2.4,"publicationDate":"2023-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139176292","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 : 2023-12-18DOI: 10.3390/photonics10121390
Shicheng Rong, Xujie Wen, Ning Ding, Jia Liao, Pingrang Hua
Highly integrated and stable devices are appealing in optical communication and sensing. This appeal arises from the presence of high refractive index contrast and high-quality waveguides. In this study, we improved the vapor proton exchange (VPE) process, enabling large-scale waveguide fabrication and addressing the issue of liquid exchange during cooling. Additionally, we have prepared and characterized planar waveguides on X-cut lithium niobate (LN) crystals. The exchanged samples exhibit α and k1 phases, refractive index contrasts as high as 0.082, and exceptional refractive index uniformity. Furthermore, we utilized the same process to fabricate channel waveguides and Y-branch waveguides. We achieved low propagation losses in channel waveguides, accompanied by small mode sizes, and low-loss Y-branch waveguides with a highly uniform beam splitting ratio. All waveguides exhibited consistent performance across multiple preparations and tests, remaining free from aging effects for three months. Our results underscore the promising potential of VPE for creating Y-branch splitters and modulators in LN crystals.
在光通信和传感领域，高集成度和高稳定性的设备非常具有吸引力。这种吸引力源于高折射率对比和高质量波导的存在。在这项研究中，我们改进了蒸汽质子交换（VPE）工艺，实现了大规模波导制造，并解决了冷却过程中的液体交换问题。此外，我们还在 X 切面铌酸锂 (LN) 晶体上制备了平面波导，并对其进行了表征。交换后的样品呈现出 α 和 k1 相，折射率对比度高达 0.082，而且折射率非常均匀。此外，我们还利用相同的工艺制作了通道波导和 Y 形分支波导。我们在通道波导中实现了低传播损耗和小模式尺寸，在 Y 支波导中实现了低损耗和高度均匀的分光比。在多次制备和测试过程中，所有波导都表现出了一致的性能，在三个月的时间里没有出现老化现象。我们的研究结果凸显了 VPE 在 LN 晶体中制造 Y 支分光器和调制器的巨大潜力。
{"title":"X-Cut Lithium Niobate Optical Waveguide with High-Index Contrast and Low Loss Fabricated by Vapor Proton Exchange","authors":"Shicheng Rong, Xujie Wen, Ning Ding, Jia Liao, Pingrang Hua","doi":"10.3390/photonics10121390","DOIUrl":"https://doi.org/10.3390/photonics10121390","url":null,"abstract":"Highly integrated and stable devices are appealing in optical communication and sensing. This appeal arises from the presence of high refractive index contrast and high-quality waveguides. In this study, we improved the vapor proton exchange (VPE) process, enabling large-scale waveguide fabrication and addressing the issue of liquid exchange during cooling. Additionally, we have prepared and characterized planar waveguides on X-cut lithium niobate (LN) crystals. The exchanged samples exhibit α and k1 phases, refractive index contrasts as high as 0.082, and exceptional refractive index uniformity. Furthermore, we utilized the same process to fabricate channel waveguides and Y-branch waveguides. We achieved low propagation losses in channel waveguides, accompanied by small mode sizes, and low-loss Y-branch waveguides with a highly uniform beam splitting ratio. All waveguides exhibited consistent performance across multiple preparations and tests, remaining free from aging effects for three months. Our results underscore the promising potential of VPE for creating Y-branch splitters and modulators in LN crystals.","PeriodicalId":20154,"journal":{"name":"Photonics","volume":"39 7","pages":""},"PeriodicalIF":2.4,"publicationDate":"2023-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139176106","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 : 2023-12-17DOI: 10.3390/photonics10121386
A. Doronkina, V. Kochubey, Anastasia V. Maksutova, A. Pravdin, A. M. Mylnikov, N. Navolokin, I. Yanina
(1) Background: Upconversion nanoparticles (UCNPs) are a promising tool for biological tissue structure visualization and photodynamic therapy (PDT). The luminescence of such NPs is excited in the spectrum’s near-infrared (NIR) region, while the NPs luminesce in the visible region. Conjugating such NPs with photodynamic dyes that absorb their luminescence makes it possible to increase the depth at which PDT is performed. (2) Methods: We conducted a comprehensive study on the possibility of using NaYF4:Er:Yb UCNPs in vivo for imaging and PDT. The NPs were synthesized by a hydrothermal method. The synthesis of NPs with a size of 80 nm and hexagonal structure was demonstrated. (3) Results: The accumulation of NPs in organs after their intravenous injection into rats was studied. The effect of NPs on the shape, size, and degree of aggregation of red blood cells (RBC) was also investigated. (4) Conclusions: The possibility of luminescent visualization of NPs in histological sections and their subcutaneous distribution is demonstrated. All investigated particles showed moderate toxicity, causing mostly reversible changes.
{"title":"NaYF4: Yb,Er Upconversion Nanoparticles for Imaging: Effect on Red Blood Cells","authors":"A. Doronkina, V. Kochubey, Anastasia V. Maksutova, A. Pravdin, A. M. Mylnikov, N. Navolokin, I. Yanina","doi":"10.3390/photonics10121386","DOIUrl":"https://doi.org/10.3390/photonics10121386","url":null,"abstract":"(1) Background: Upconversion nanoparticles (UCNPs) are a promising tool for biological tissue structure visualization and photodynamic therapy (PDT). The luminescence of such NPs is excited in the spectrum’s near-infrared (NIR) region, while the NPs luminesce in the visible region. Conjugating such NPs with photodynamic dyes that absorb their luminescence makes it possible to increase the depth at which PDT is performed. (2) Methods: We conducted a comprehensive study on the possibility of using NaYF4:Er:Yb UCNPs in vivo for imaging and PDT. The NPs were synthesized by a hydrothermal method. The synthesis of NPs with a size of 80 nm and hexagonal structure was demonstrated. (3) Results: The accumulation of NPs in organs after their intravenous injection into rats was studied. The effect of NPs on the shape, size, and degree of aggregation of red blood cells (RBC) was also investigated. (4) Conclusions: The possibility of luminescent visualization of NPs in histological sections and their subcutaneous distribution is demonstrated. All investigated particles showed moderate toxicity, causing mostly reversible changes.","PeriodicalId":20154,"journal":{"name":"Photonics","volume":"22 32","pages":""},"PeriodicalIF":2.4,"publicationDate":"2023-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138966208","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 : 2023-12-16DOI: 10.3390/photonics10121385
E. K. Mikhailov, K. Bobkov, A. Levchenko, V. Velmiskin, D.V. Khudyakov, S. Aleshkina, T.S. Zaushitsyna, M. Bubnov, D. Lipatov, M. Likhachev
We demonstrated an optimization of a picosecond fiber amplifier based on Yb-doped tapered fiber in a spectral range of 1030 nm. Nonlinear effects limiting peak power scaling (stimulated Raman scattering and four-wave mixing) were studied and factors affecting their threshold were established, such as gain, diameter profile along the length of taper, output mode field diameter, and numerical aperture of a pump. By determining the optimal amplification regime and manufacturing advanced tapered fibers, we amplified 13 ps pulses to a record-high peak power of 1 MW at a wavelength of 1029 nm directly at the output of the fiber at an average power of 13.8 W. Four-wave mixing was the limiting factor, and the total fraction of deleterious components in the output spectrum was ~2%. The quality of the output beam was close to being diffraction limited (M2 < 1.2).
{"title":"Picosecond Pulse Tapered Fiber Amplifier Operated near 1030 nm with Peak Power up to 1 MW","authors":"E. K. Mikhailov, K. Bobkov, A. Levchenko, V. Velmiskin, D.V. Khudyakov, S. Aleshkina, T.S. Zaushitsyna, M. Bubnov, D. Lipatov, M. Likhachev","doi":"10.3390/photonics10121385","DOIUrl":"https://doi.org/10.3390/photonics10121385","url":null,"abstract":"We demonstrated an optimization of a picosecond fiber amplifier based on Yb-doped tapered fiber in a spectral range of 1030 nm. Nonlinear effects limiting peak power scaling (stimulated Raman scattering and four-wave mixing) were studied and factors affecting their threshold were established, such as gain, diameter profile along the length of taper, output mode field diameter, and numerical aperture of a pump. By determining the optimal amplification regime and manufacturing advanced tapered fibers, we amplified 13 ps pulses to a record-high peak power of 1 MW at a wavelength of 1029 nm directly at the output of the fiber at an average power of 13.8 W. Four-wave mixing was the limiting factor, and the total fraction of deleterious components in the output spectrum was ~2%. The quality of the output beam was close to being diffraction limited (M2 < 1.2).","PeriodicalId":20154,"journal":{"name":"Photonics","volume":"55 34","pages":""},"PeriodicalIF":2.4,"publicationDate":"2023-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138995639","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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