Photonics最新文献

{"title":"High-Precision Temperature Control of Laser Crystals","authors":"Xiang Zhang, Hang Xu, Liwen Feng, Zhongqi Liu, Tianyi Wang, Jinqiang Xu, Shengwen Quan, Senlin Huang","doi":"10.3390/photonics11080745","DOIUrl":"https://doi.org/10.3390/photonics11080745","url":null,"abstract":"Temperature control is important in second harmonic generation (SHG) based on non-critical phase matching, which is widely used in the accelerator field to generate drive lasers. To further improve the stability of the drive laser for the DC-SRF photocathode electron gun at Peking University, a high-precision temperature control oven for lithium borate (LBO) crystals was developed. The oven’s structure was designed to minimize heat exchange with the external environment. The temperature control circuit uses a thermoelectric cooler to ensure the temperature stability of the sampling circuit. The program utilizes a cascaded proportional-integral-derivative and an anti-saturation integral algorithm to achieve high-precision temperature control. Experiments showed that fluctuation at the working temperature of the LBO crystal in this oven was within ±0.009 °C, corresponding to a root mean square (RMS) jitter of 0.003 °C, and the long-term power fluctuation of the 13.7 W green laser generated with SHG was less than 1%.","PeriodicalId":20154,"journal":{"name":"Photonics","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141925330","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}

{"title":"Analyses of an Ultra-Wideband Absorber from UV-B to Middle-IR Utilizing a Square Nanopillar and a Square Hollow Embedded in a Square Cavity of the Top Layer of Multilayer Metamaterials","authors":"Chia-Te Liao, Pei-Xiu Ke, Chia-Min Ho, Cheng-Fu Yang, Tung-Lung Wu","doi":"10.3390/photonics11080742","DOIUrl":"https://doi.org/10.3390/photonics11080742","url":null,"abstract":"In this study, an ultra-wideband absorber spanning from UV-B to middle-IR was designed and analyzed using a novel structure. The multilayer metamaterial, arranged from bottom to top, consisted of an Al metal layer, a lower SiO2 layer, a graphite layer, another SiO2 layer, a thin Ti layer, and a top SiO2 layer. The top layer of SiO2 had a 200 nm square cavity etched out, and then a square Ti nanopillar and a square Ti hollow outside a Ti nanopillar were embedded. This specific arrangement was chosen to maximize the absorption properties across a broad spectrum. The absorption spectrum of the designed absorber was thoroughly analyzed using the commercial finite element analysis software COMSOL Multiphysics® (version 6.0). This analysis confirmed that the combination of these various components achieved perfect absorption and an ultra-wideband response. The synergistic interaction between the layers and the nanopillars structure contributed significantly to the absorber’s efficiency, making it a promising candidate for applications requiring broad-spectrum absorption. The comprehensive analyses of the parameters for different structures demonstrated that the effects of guided-mode resonance, coupling resonance, optical impedance matching, and propagating surface plasmon resonance existed in the investigated structure. The optimal model, determined through analyses using COMSOL Multiphysics®, showed that the broadband absorption in the range of 270 to 3600 nm, spanning from UV-B to middle-IR, exceeded 90.0%. The average absorption rate within this range was 0.967, with the highest reaching a near-perfect absorptivity of 99.9%. We also compared three absorption spectra in this study: the t1–t6 flat structure, the t1–t5 flat structure with t6 featuring a square cavity, and the structure proposed in this study. This demonstrates that a square nanopillar and a square hollow embedded in a square cavity can enhance the absorptive properties of the absorber.","PeriodicalId":20154,"journal":{"name":"Photonics","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141926456","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}

{"title":"Interferometrically Enhanced Intensity and Wavelength Modulation in Tunable Diode Laser Spectroscopy","authors":"Sander Vervoort, Marcus Wolff","doi":"10.3390/photonics11080740","DOIUrl":"https://doi.org/10.3390/photonics11080740","url":null,"abstract":"Tunable diode laser spectroscopy (TDLS) is a measurement technique with high spectral resolution. It is based on tuning the emission wavelength of a semiconductor laser by altering its current and/or its temperature. However, adjusting the wavelength leads to a change in emission intensity. For applications that rely on modulated radiation, the challenge is to isolate the true spectrum from the influence of extraneous instrumental contributions, particularly residual intensity and wavelength modulation. We present a novel approach combining TDLS with interferometric techniques, exemplified by the use of a Mach–Zehnder interferometer, to enable the separation of intensity and wavelength modulation. With interferometrically enhanced intensity modulation, we reduced the residual wavelength modulation by 83%, and with interferometrically enhanced wavelength modulation, we almost completely removed the residual derivative of the signal. A reduction in residual wavelength modulation enhances the spectral resolution of intensity-modulated measurements, whereas a reduction in residual intensity modulation improves the signal-to-noise ratio and the sensitivity of wavelength-modulated measurements.","PeriodicalId":20154,"journal":{"name":"Photonics","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141927385","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}

{"title":"A Numerical Study of Microwave Frequency Comb Generation in a Semiconductor Laser Subject to Modulated Optical Injection and Optoelectronic Feedback","authors":"Chenpeng Xue, Wei Chen, Beibei Zhu, Zuxing Zhang, Yanhua Hong","doi":"10.3390/photonics11080741","DOIUrl":"https://doi.org/10.3390/photonics11080741","url":null,"abstract":"This study presents a comprehensive numerical investigation on the generation of a microwave frequency comb (MFC) using a semiconductor laser subjected to periodic-modulated optical injection. To enhance performance, optoelectronic feedback is incorporated through a dual-drive Mach–Zehnder modulator. The results show that the first optoelectronic feedback loop, with a delay time inversely proportional to the modulation frequency, can optimize MFC generation through a mode-locking effect and the second optoelectronic feedback loop with a multiple delay time of the first one can further enhance the performance of the MFC. The comb linewidth appears to decrease with the increase in the second-loop delay time in the power function. These results are consistent with experimental observations reported in the literature. We also explore the impact of the feedback index on comb contrast, the statistical characteristics of the central 128 lines within the MFC, and side peak suppression. The simulation results demonstrate the presence of an optimal feedback index. The study also reveals that linewidth reduction, through increasing the feedback index and delay time, comes at the cost of declining side peak suppression. These findings collectively contribute to a deeper understanding of the factors influencing MFC generation and pave the way for the design and optimization of high-performance MFC systems for various applications.","PeriodicalId":20154,"journal":{"name":"Photonics","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141925896","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}

{"title":"Efficient Depth Measurement for Live Control of Laser Drilling Process with Optical Coherence Tomography","authors":"Jinhan Zhao, Chaoliang Zhang, Yaoyu Ding, Libing Bai, Yuhua Cheng","doi":"10.3390/photonics11080743","DOIUrl":"https://doi.org/10.3390/photonics11080743","url":null,"abstract":"Laser drilling is widely used for fabricating holes in the semiconductor industry due to high throughput and a small heat-affected zone. However, it produces varying depths owing to uncertain external conditions and requires live control at the rate of a few tens of kHz to handle the fast material removal rate. Optical coherent tomography is capable of in situ acquiring a raw interferogram at a high rate (>80 kHz), but the depth extraction is slow due to the involved heavy Fast Fourier Transform (FFT). To address this, an efficient depth-tracking algorithm is proposed to save the FFT. It searches the depth in the raw interferogram locally with a known last depth given the two truths that only one depth exists and the adjacent depths do not change significantly. The proposed algorithm was proven to expedite the measuring rate six times with sub-pixel tracking precision. To further secure the rate against the interrupting of the system, the tracking process is parallelly implemented in a field-programmable gate array. The closed-loop control tests were conducted on probe cards with depth variations introduced by offsetting laser focus. The proposed method maintained a uniform depth, with variations reduced by 80% compared to traditional methods.","PeriodicalId":20154,"journal":{"name":"Photonics","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141929604","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}

{"title":"Experimental Study on Transverse Mode Instability of All-Fiber Single-Frequency Amplifier Based on Tapered Yb-Doped Fiber","authors":"Yue Tao, Zhengfei Mo, Pengrui Kang, Man Jiang, Can Li, Jin-yong Leng, Pu Zhou, Zongfu Jiang","doi":"10.3390/photonics11080696","DOIUrl":"https://doi.org/10.3390/photonics11080696","url":null,"abstract":"We experimentally studied the transverse mode instability (TMI) threshold of a linearly polarized single-frequency fiber laser amplifier constructed with tapered ytterbium-doped fiber (TYDF) under different bending diameters. The TMI threshold increased from 333 W to 451 W by reducing the bending diameter from 16 cm to 12 cm, which was accompanied by the deterioration of the beam quality from 1.47 to 1.67. The anomalous characteristics between the TMI threshold, bending diameter, and beam quality are mainly attributed to the decreased bending loss of higher-order mode (HOM) content as a result of the increased system heat loads caused by a tight bending-induced loss of amplification efficiency. It is believed that the presented results will provide useful guidelines for the design of high-power single-frequency fiber amplifiers.","PeriodicalId":20154,"journal":{"name":"Photonics","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141798708","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}

{"title":"Scintillation and Luminescent Properties of the (Gd,Y)3Al2Ga3O12:Ce Ceramics Obtained by Compaction of Green Bodies Using Digital Light Processing 3D Printing","authors":"L. V. Ermakova, V. Smyslova, Valery V. Dubov, P. Karpyuk, Petr S. Sokolov, I. Komendo, A. Bondarau, Vitaly Mechinsky, Mikhail V. Korzhik","doi":"10.3390/photonics11080695","DOIUrl":"https://doi.org/10.3390/photonics11080695","url":null,"abstract":"Dense and transparent ceramic samples of a (Gd,Y)3Al2Ga3O12:Ce scintillator were obtained by using stereolithography-based Digital Light Processing (DLP) 3D printing for compacting, subsequent burnout, and pressureless sintering. The effects of stoichiometric deviations and green body compaction methods (uniaxial pressing versus DLP 3D printing) on the optical, luminescent, and scintillation properties of ceramics were analyzed. An excess of Y and Gd in the composition led to an increase in transmittance and to the acceleration of the scintillation kinetics. Moreover, transparent ceramics made of 3D-printed green bodies were found to be superior in light yield to the samples, which were prepared from the same powders and densified by uniaxial pressing.","PeriodicalId":20154,"journal":{"name":"Photonics","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141801632","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}

{"title":"Experimental Investigation on the Dynamics Characteristics of a Two-State Quantum Dot Laser under Optical Feedback","authors":"Yanfei Zheng, G. Xia, Xiaodong Lin, Ruilin Fang, Qingqing Wang, Fengling Zhang, Zhengmao Wu","doi":"10.3390/photonics11080692","DOIUrl":"https://doi.org/10.3390/photonics11080692","url":null,"abstract":"We experimentally investigate the dynamics characteristics of a two-state quantum dot laser (TSQDL) subject to optical feedback. Firstly, we inspect the impact of the temperature on the power-current characteristics of the ground state (GS) lasing and the excited state (ES) lasing in the TSQDL operating at free-running. The results demonstrate that with the decrease in the temperature, the threshold current for GS lasing (IthGS) and the threshold current for ES lasing (IthES) decrease very slowly. There exists a current for GS quenching (IQGS), which is gradually increased with the decrease in the temperature. After introducing optical feedback, the overall trend of change is similar to those obtained under free-running. Next, through inspecting the time series and power spectrum of the output from the TSQDL under optical feedback, the dynamical characteristics of the TSQDL are investigated under different feedback ratios, and diverse dynamical states including quasi-chaos pulse package, chaos state, regular pulse package, quasi-period two, quasi-regular pulsing, and chaos regular pulse package have been observed. Finally, for the TSQDL biased at three different cases: lower than IthES, slightly higher than IthES, and higher than IthES, nonlinear dynamic state evolutions with the increase in feedback ratio are inspected, respectively. The results show that, for the TSQDL biased at lower than IthES, it presents an evolution route of stable state—quasi-chaos pulse package—chaos state—regular pulse package. For the TSQDL biased at slightly larger than IthES, it presents an evolution route of stable state—quasi-regular pulsing—quasi-period two—chaos regular pulse package. For the TSQDL biased at higher than IthES, the TSQDL always behaves stable state within the range of feedback ratio that the experiment can achieve. However, with the increase in optical feedback ratio, the number of longitudinal modes for GS lasing and ES lasing are changed.","PeriodicalId":20154,"journal":{"name":"Photonics","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141802837","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}

{"title":"Unraveling the Dominant Size Effect in Polydisperse Solutions and Maximal Electric Field Enhancement of Gold Nanoparticles","authors":"Quang Truong Pham, Gia Long Ngo, Chi Thanh Nguyen, Isabelle Ledoux-Rak, N. D. Lai","doi":"10.3390/photonics11080691","DOIUrl":"https://doi.org/10.3390/photonics11080691","url":null,"abstract":"In this study, we systematically investigate theoretically and experimentally the plasmonic effect and roles of big and small gold nanoparticles (Au NPs) within a mixed solution. The polydisperse solution was initially prepared by mixing small (10, 30 nm) Au NPs with larger ones (50, 80 nm), followed by measuring the extinction using ultraviolet–visible (UV-vis) spectroscopy. The experimental results clearly showed that the extinction of the mixed solution is predominantly influenced by the presence of the larger NPs, even though their quantity is small. Subsequently, we conducted simulations to explore the plasmonic properties of Au NPs of different sizes as well as their mixings and to validate the experimental results. To explain the deviation of the extinction spectra between experimental observations and simulations, we elaborated a simulation model involving the mixture of spherical Au NPs with ellipsoidal NPs, thus showing agreement between the simulation and the experiment. By performing simulations of plasmonic near-field of NPs, our investigation revealed that the maximal electric field intensity does not occur precisely at the plasmonic resonant wavelength but rather at a nearby redder wavelength. The optimal size of the Au NP dispersed in water for achieving the highest field enhancement was found to be 60 nm, with an excitation wavelength of 553.7 nm. These interesting findings not only enrich our understanding of plasmonic NPs’ optical behavior but also guide researchers for potential applications in various domains.","PeriodicalId":20154,"journal":{"name":"Photonics","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141806380","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}

{"title":"Smartphone-Readable Optical-Fiber Quasi-Distributed Phosphorescent Temperature Sensor","authors":"T. Eftimov, I. Kostova, S. Fouzar, D. Brabant, Kristian Nikolov, Veselin Vladev","doi":"10.3390/photonics11080694","DOIUrl":"https://doi.org/10.3390/photonics11080694","url":null,"abstract":"In this paper we present the principle of operation, fabrication and performance of a phosphorescent optical-fiber quasi-distributed sensor with contactless smartphone interrogation. An array of short strong corrugated long-period gratings (C-LPG) is used as a platform to spatially locate and to excite the phosphors whose time responses are temperature-dependent. The C-LPG array was fabricated using a pulsed CO2 laser. The quasi-distributed sensing array is excited by a UV LED and the normalized differential rise/decay time response measured by a smartphone is used as a measure of the temperature. The sensing spots have a volume smaller than 0.5 μL, can be separated by several millimeters to several meters and the interrogation can be simultaneous or in a sequence. The response and the sensitivity to temperature have been measured. The sensing array has been shown to measure abrupt and gradual temperature changes in space as well as time-dependent processes in the 0 °C to 100 °C range and with a measurement time of 1 s.","PeriodicalId":20154,"journal":{"name":"Photonics","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141805783","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}