1 广东大湾区空天信息研究院，广东 广州 510700
2 广东省太赫兹量子电磁学重点实验室，广东 广州 510700
3 中国科学院大学，北京 100049
深紫外激光具有光子能量高、波长短等特点，在激光加工、半导体光刻等领域中具有重要的应用价值。固体激光非线性频率变换是实现高功率、高相干性深紫外激光输出的主要方式之一。采用全固态532 nm激光作为基频光、国产商用CsLiB6O10（CLBO）晶体作为频率变换晶体，在基频光功率为34.2 W时，实现了平均功率为14 W、重复频率为100 kHz、脉冲宽度为1.8 ns的266 nm深紫外激光输出，光-光转换效率达到41%。该深紫外光源具有效率高、结构紧凑的优点，验证了国产商用CLBO晶体的实用性，可进一步获得更稳定、更高功率的深紫外激光输出。
激光器 深紫外激光 全固态激光 CsLiB6O10晶体 高功率
Author Affiliations
Abstract
1 Chinese Academy of Sciences, GBA branch of Aerospace Information Research Institute, Guangzhou, China
2 University of Chinese Academy of Sciences, Beijing, China
A 60-mW solid-state deep ultraviolet (DUV) laser at 193 nm with narrow linewidth is obtained with two stages of sum frequency generation in LBO crystals. The pump lasers, at 258 and 1553 nm, are derived from a homemade Yb-hybrid laser employing fourth-harmonic generation and Er-doped fiber laser, respectively. The Yb-hybrid laser, finally, is power scaling by a 2 mm × 2 mm × 30 mm Yb:YAG bulk crystal. Accompanied by the generated 220-mW DUV laser at 221 nm, the 193-nm laser delivers an average power of 60 mW with a pulse duration of 4.6 ns, a repetition rate of 6 kHz, and a linewidth of ∼640 MHz. To the best of our knowledge, this is the highest power of 193- and 221-nm laser generated by an LBO crystal ever reported as well as the narrowest linewidth of 193-nm laser by it. Remarkably, the conversion efficiency reaches 27% for 221 to 193 nm and 3% for 258 to 193 nm, which are the highest efficiency values reported to date. We demonstrate the huge potential of LBO crystals for producing hundreds of milliwatt or even watt level 193-nm laser, which also paves a brand-new way to generate other DUV laser wavelengths.
193 nm solid-state laser deep ultraviolet LBO crystal sum frequency mixing narrow linewidth Advanced Photonics Nexus
2024, 3(2): 026012
1 中国科学院合肥物质科学研究院等离子体物理研究所, 安徽 合肥 230031
2 中国科学技术大学, 安徽 合肥 230026
等离子体发射光谱是研究托卡马克等离子体物理过程的重要诊断手段之一。边界等离子体中存在着复杂的原子分子物理过程, 部分较弱的粒子光谱信号混杂着大量噪声, 能否有效去除噪声、提高信号质量对后续利用其分析理解实验中相关物理过程具有重要意义。以仿真信号和真实托卡马克实验中钨原子光谱数据作为研究对象, 采用信噪比(SNR) 和均方根误差(RMSE) 作为滤波效果的评价依据, 对小波阈值去噪处理方法的去噪效果进行了研究。仿真实验对比分析表明: 选取 sym8 小波基、4 层小波分解、启发式阈值计算以及渐进半软阈值函数进行小波去噪时, 可获得最大信噪比 19.2166，最小均方根误差 0.0290。进而将这些最佳匹配参数应用于实测偏滤器钨原子光谱信号处理中, 也取得较好的去噪效果。结果表明: 小波阈值去噪能够有效地消除偏滤器钨原子光谱信号中的噪声, 同时较好地保留有用信号, 避免信号失真, 显著提高了信号质量。
光谱学 偏滤器钨原子光谱信号 小波变换 阈值去噪 信噪比 均方根误差 spectroscopy spectral signal of tungsten atom in divertor wavelet transform threshold denoising signal-to-noise ratio root mean square error
北京航空航天大学 仪器科学与光电工程学院, 北京 100191
通过建立POL(Polarization Observation by The Lens-Effective Tracing)保偏光纤定轴系统仿真模型, 分析了定轴过程中光纤发生微小位移以及相机像元尺寸所产生的误差。为了减少该种误差, 实现自动对轴, 提出了一种基于POL技术的保偏光纤定轴方法——POLF(Polarization Observation by The Lens-Effective with Fiber-Focus)定轴法。对该定轴方法进行了仿真验证, 并通过对轴实验对其定轴精度进行了验证。实验结果证明POLF定轴算法能够实现优于1°的定轴精度。
保偏光纤 POL法 定轴 PM-fibers POL technique azimuthal alignment
Author Affiliations
Abstract
1 State Key Laboratory of Luminescent Materials and Devices and Institute of Optical Communication Materials, South China University of Technology, Guangzhou 510640, China
2 College of Optoelectronic Technology, Chengdu University of Information Technology, Chengdu 610225, China
3 Guangdong Engineering Technology Research and Development Center of High-Performance Fiber Laser Techniques and Equipments, Zhuhai 519031, China
4 Guangdong Engineering Technology Research and Development Center of Special Optical Fiber Materials and Devices, Guangzhou 510640, China
5 Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques, South China University of Technology, Guangzhou 510640, China
A noise-sidebands-free and ultra-low relative intensity noise (RIN) 1.5 μm single-frequency fiber laser is demonstrated for the first time to our best knowledge. Utilizing a self-injection locking framework and a booster optical amplifier, the noise sidebands with relative amplitudes as high as 20 dB are completely suppressed. The RIN is remarkably reduced by more than 64 dB at the relaxation oscillation peak to retain below 150 dB/Hz in a frequency range from 75 kHz to 50 MHz, while the quantum noise limit is 152.9 dB/Hz. Furthermore, a laser linewidth narrower than 600 Hz, a polarization-extinction ratio of more than 23 dB, and an optical signal-to-noise ratio of more than 73 dB are acquired simultaneously. This noise-sidebands-free and ultra-low-RIN single-frequency fiber laser is highly competitive in advanced coherent light detection fields including coherent Doppler wind lidar, high-speed coherent optical communication, and precise absolute distance coherent measurement.
Lasers, fiber Lasers, single-mode Fluctuations, relaxations, and noise Photonics Research
2018, 6(4): 04000326
1 上海海事大学 商船学院, 上海 201306
2 大连海事大学 物理系, 辽宁 大连 116026
将发射光谱信号引入到辉光放电等离子体天线开启时间测量当中，根据等离子体光信号与激励电压信号的时间差测出辉光等离子体天线的开启时间。结果发现该方法可有效测量直流和频率较高的交流辉光等离子体天线开启时间。直流和kHz级交流等离子体天线开启时间约为在1 ms，MHz级交流等离子体天线开启时间在0.5 ms左右。而对于50 Hz低频交流等离子体天线，由于放电状态不稳定，测量误差较大。天线的开启时间与激励电源的功率和电源的响应时间有很大关系。在一定范围内，随放电功率增加，天线的开启时间缩短。同时放电功率的增加也增大了天线开启时间测量结果的可重复性，误差减小，为1%~2%。
等离子体 天线 开启时间 光电时差 plasma antenna switch-on time light-electricity time difference 强激光与粒子束
2017, 29(5): 052001
