520nm泵浦780nm+1560nm双共振光学参量振荡器

我们在实验中演示了520nm单频绿光泵浦的基于周期极化磷酸钛氧钾(PPKTP)晶体的780nm+1560nm双共振光参量振荡器,高效制备780nm+1 560nm连续可调谐双色下转换光场。该参量振荡器可输出93.3 mW的1 560nm单频激光和44.6mW的780nm单频激光。通过改变PPKTP晶体的温度所得到的波长粗调范围为:信号光1 529.81nm~1 573.83nm(~44nm),闲置光788.26nm~777.20nm(~11nm);通过连续调谐520nm泵浦激光频率初步得到的闲置光在780.24nm(铷原子D2线)处频率连续调谐范围约1.6GHz。     

三硼酸锂晶体上1064 nm,532 nm,355 nm三倍频增透膜的设计

采用矢量法设计了三硼酸锂晶体上1064 nm、532 nm和355 nm三倍频增透膜,结果表明1064 nm、532 nm和355 nm波长的剩余反射率分别为0.0017%、0.0002%和0.0013%。根据误差分析,薄膜制备时沉积速率精度控制在 5.5%时,1064 nm、532 nm和355 nm波长的剩余反射率分别增加至0.20%、0.84%和1.89%。当材料折射率的变化控制在 3%时,1064 nm处的剩余反射率增大为0.20%,532 nm和355 nm处分别达0.88%和0.24%。与薄膜物理厚度相比,膜层折射率对剩余反射率的影响大。对膜系敏感层的分析表明,在1064 nm和355 nm波长,从入射介质向基底过渡的第二层膜的厚度变化对剩余反射率的影响最大,其次是第一膜层。在532 nm波长,第一和第三膜层是该膜系的敏感层。同时发现,由于薄膜材料的色散,1064 nm5、32 nm和355 nm波长的剩余反射率分别增加至0.15%、0.31%和1.52%。     

1 064, 532和680 nm波长的反射-吸收复合型防护膜的研制

 针对1 064, 532 和 680 nm波长激光, 以聚碳酸酯 （PC） 为镀膜基底, 钕玻璃激光中心波长为1 064 nm, 采用六分之一加三分之一膜系的反射膜系设计,以氧化锆为高折射率膜层材料,氯化酞菁铝掺杂的氧化硅为低折射率膜层材料,通过溶胶-凝胶法镀21层膜,并在多层反射膜与PC基底之间插入张力匹配层,实现了钕玻璃激光器1 064 nm主频和532 nm二倍频波长激光的反射,以及680 nm波长红宝石激光的同时吸收,1 064,532和680 nm波长处的透射率分别为1.67％,18.24％和2.4％。     

1 064, 532和680 nm波长的反射-吸收复合型防护膜的研制

针对1 064, 532 和 680 nm波长激光, 以聚碳酸酯 （PC） 为镀膜基底, 钕玻璃激光中心波长为1 064 nm, 采用六分之一加三分之一膜系的反射膜系设计,以氧化锆为高折射率膜层材料,氯化酞菁铝掺杂的氧化硅为低折射率膜层材料,通过溶胶-凝胶法镀21层膜,并在多层反射膜与PC基底之间插入张力匹配层,实现了钕玻璃激光器1 064 nm主频和532 nm二倍频波长激光的反射,以及680 nm波长红宝石激光的同时吸收,1 064,532和680 nm波长处的透射率分别为1.67％,18.24％和2.4％。     

All-Solid-State Nd:YAG Laser Operating at 1064nm and 1319nm under 885nm Thermally Boosted Pumping

We report a high-effciency Nd：YAG laser operating at 1064 nm and 1319nm, respectively, thermally boosted pumped by an all-solid-state Q-switched Ti：sapphire laser at 885 nm. The maximum outputs of 825.4 m W and 459.4mW, at 1064nm and 1319nm respectively, are obtained in a 8-ram-thick 1.1 at.% Nd：YAG crystal with 2.1 W of incident pump power at 885nm, leading to a high slope efficiency with respect to the absorbed pump power of 68.5% and 42.0%. Comparative results obtained by the traditional pumping at 808nm are presented, showing that the slope efficiency and the threshold with respect to the absorbed pump power at 1064nm under the 885nm pumping are 12.2% higher and 7.3% lower than those of 808rim pumping. At 1319nm, the slope efficiency and the threshold with respect to the absorbed pump power under 885nm pumping are 9.9% higher and 3.5% lower than those of 808 nm pumping. The heat generation operating at 1064 nm and 1319 nm is reduced by 19.8% and 11.1%, respectively.     

Molecular iodine laser optically pumped at 521 nm and 531 nm

We report the observation and identification of over 50 new cw laser lines belonging to the B³∏?X¹∑ system of I₂ optically pumped by a single mode krypton ion laser. When pumping at 531 nm, simultaneous oscillation was achieved on up to 16 lines in the range 540 nm to 650 nm. This system offers considerable potential as a multi-wavelength laser source in interferometry.     

1064 nm Nd:YAG laser intracavity pumped at 946 nm

We present for the first time a Nd:YAG laser emitting at 1064 nm intracavity pumped by a 946 nm diode-pumped Nd:YAG laser. A 885 nm laser diode is used to pump the first Nd:YAG crystal emitting at 946 nm, and the second Nd:YAG laser emitting at 1064 nm intracavity pumped at 946 nm. We achieved an output power of 7.97 W at 1064 nm for an absorbed pump power at 946 nm of 9.55 W, corresponding to an optical efficiency of 83.4%. The beam quality M² quality factor is about 1.1 at the maximum output power.     

Holmium-doped fluoride fiber laser at 2950 nm pumped at 1175 nm

We report a single-mode, highly stable, continuous-wave Ho³⁺: ZBLAN fiber laser. The system was pumped by a 1175-nm fiber Raman laser and emitted at ～2950 nm. The optical-to-optical conversion efficiency was 43% that is the highest reported in the literature. Characterizations revealed a quasigaussian intensity profile with a power stability of less than 1%. This high stability relies on the single-wavelength emission of the system because the system does not require simultaneous oscillation at 2100 nm. Coincidence between the emission wavelength and the absorption peak of water makes the system suitable to replace a high-power (～9.34-W) Er³⁺: ZBLAN fiber laser for cutting materials with high moisture content.     

Multilayers with high-reflectivity at 19.5 nm and low-reflectivity at 30.4 nm

The multilayer （ML） mirror with high-reflectivity （HR） at a specific emission line of 19.5 nm （Fe line） and low-reflectivity （LR） at 30.4 nm （He line） is needed to be designed and fabricated for observing the image of sun. Based on a variety of optimizations utilized different structures, the design is performed and the final results demonstrate that the reflectivity at 30.4 nm does not achieve minimum value when the reflectivity at 19.5 nm reaches the maximum value. The tradeoff should be done between the HR at 19.5 nm and LR at 30.4 nm. One optimized mirror is fabricated by direct current magnetron sputtering and characterized by grazing-incident X-ray diffraction （XRD） and synchrotron radiation （SR）. The experimental results demonstrate that the ML achieves the reflectivity of 33.3% at 19.5 nm and of 9.6× 10-4 at 30.4 nm at the incident angle of 13°.     

在19.5 nm处高反在30.4 nm处抑制的双功能薄膜

 研究了极紫外波段的双功能光学元件。采用周期膜叠加的思想,运用遗传方法优化设计了在19.5 nm处高反,在30.4 nm处抑制的双功能多层膜。采用磁控溅射技术制备了多层膜,利用X射线衍射仪测试了多层膜的结构,在国家同步辐射实验室测试了双功能多层膜的反射特性。结果表明：制备出的双功能膜性能与设计相符,在入射角13°,19.5 nm处的反射率达到33.3%,接近传统的19.5 nm周期高反膜的反射率,并且在30.4 nm附近将反射率由1.1%降到9.6×10^-4。     

473 nm和946 nm双波长输出的全固态Nd:YAG激光器

设计并实现了473 nm和946 nm双波长输出的全固态Nd:YAG激光器.利用激光二极管端面泵浦Nd:YAG晶体,在三镜折叠谐振腔中插入Brewster窗片作为起偏器,通过周期极化晶体PPKTP内腔倍频获得473 nm蓝光输出.同时利用Nd:YAG激光晶体的热退偏效应,把Brewster窗片作为基频光输出耦合镜,实现946 nm激光输出.通过调谐PPKTP的温度,优化了倍频光和基频光的输出功率.泵浦功率25W时,实验获得了1.8W的473 nm倍频蓝光和0.8W的946 nm基频激光输出.     

Sub-38 nm resolution tabletop microscopy with 13 nm wavelength laser light

We have acquired images with a spatial resolution better than 38 nm by using a tabletop microscope that combines 13 nm wavelength light from a high-brightness tabletop laser and Fresnel zone plate optics. These results open a gateway to the development of compact and widely available extreme-ultraviolet imaging tools capable of inspecting samples in a variety of environments with a 15-20 nm spatial resolution and a picosecond time resolution.     

单模光纤1250～1650 nm超平坦宽带耦合器

随着光纤技术的飞速发展和应用．光纤无源器件顺应当前形势也获得很大的发展空间,其中光纤熔锥器件具有制作简单、性能可靠、价格便宜及技术指标优越等优点,从而广受青睐。在熔锥器件中,光纤耦合器是广为应用的基础元器件。目前为实现全光通信。光纤超平坦宽带耦合器则成为热点课题。利用特殊相位补偿工艺方法,研制出单模光纤超平坦宽带耦合器。其工作波长范围为1250～1650nm,3dB带内最大插损偏差小于等于0．4dB,带内最大附加损耗小于等于0．1dB,方向性(输入侧非注人光的一端的输出光功率与注入光功率的比值)大于等于66．5dB,偏振相关性小于等于0．1dB。研制方法有很高的成品率,可批量生产。     

Observation of 280 nm and 298 nm ultraviolet emissions in sodium vapor

Dye laser output around 578 nm is utilized to pump sodium vapor confined in a heatpipe. Fixed wavelength ultraviolet emissions at 280 nm and 298 nm are observed for the first time and can be explained by anti-Stokes Raman scattering and two photon emission respectively. In addition, there are tunable emission lines around 280 nm and 298 nm, the frequencies of which vary with pump laser wavelength. These tunable lines can be explained by four-wave mixing schemes.     

在19.5 nm处高反在30.4 nm处抑制的双功能薄膜

研究了极紫外波段的双功能光学元件。采用周期膜叠加的思想,运用遗传方法优化设计了在19.5 nm处高反,在30.4 nm处抑制的双功能多层膜。采用磁控溅射技术制备了多层膜,利用X射线衍射仪测试了多层膜的结构,在国家同步辐射实验室测试了双功能多层膜的反射特性。结果表明：制备出的双功能膜性能与设计相符,在入射角13°,19.5 nm处的反射率达到33.3%,接近传统的19.5 nm周期高反膜的反射率,并且在30.4 nm附近将反射率由1.1%降到9.6×10-4。     

1150 nm High-Power Fiber Laser Oscillator Pumped by 976 nm Laser Diode

We present an all-fiber 1150 nm Yb-doped fiber laser oscillator pumped by a 976 nm laser diode. To suppress amplified spontaneous emission and avoid parasitic laser oscillation, we propose a long-length gain fiber and a high-reflectivity output fiber Bragg grating in the fiber laser oscillator. The 1150 nm band single-mode fiber laser with output power of 20.5 W is demonstrated at room temperature. The optical-to-optical conversion efficiency ranges up to 51.6% at the maximum output. The central wavelength of the fiber laser oscillator is 1150.35 nm, and its 3 dB spectral width is 0.72 nm. No evidence of amplified spontaneous emission, residual pump light, or parasitic laser oscillation were observed in the experiments. The high-power 1150 nm fiber laser oscillator can be used as a pump source in the development of a 3 μm Ho-doped fiber laser.     

Tuning ranges of 355 nm pumped dyes from 410 to 715 nm

Wavelength tuning ranges and optimal concentrations are reported for 16 commercially available laser dyes pumped with the third harmonic of a Nd-YAG laser at 355 nm. The laser dye outputs cover the visible range from 410 to 715 nm.     

Precision measurement of two iodine lines at 585 nm and 549 nm

The transition frequencies of thei-component of the R(99)15-1 and thew-component of the R(85)26-0 transition in the B-X system of molecular¹²⁷I₂ have been determined with an overall relative standard uncertainty of 1.3 · 10^?10. For this purpose a commercial linear dye laser has been modified and stabilized to the corresponding iodine line. This dye laser serves as a transportable frequency standard which is compared with the wavelength standards of the PTB. The evaluation of an experiment for testing special relativity at the test storage ring (TSR) in Heidelberg is based on the precision of the reported interferometric wavelength comparison.     

1064 nm Nd:YVO4 laser intracavity pumped at 912 nm and sum-frequency mixing for an emission at 491 nm

We present for the first time a Nd:YVO(4) laser emitting at 1064 nm intracavity pumped at 912 nm by a Nd:GdVO(4) laser. We carried out a model to design the system properly, and laser performance was experimentally investigated. Intracavity sum-frequency mixing at 912 and 1064 nm was then realized in a BiBO crystal to reach the blue range. We obtained a cw output power of 155 mW at 491 nm with a pump laser diode emitting 20 W at 808 nm.     

High-power laser diodes of the spectral region of 808 nm and 980 nm

A technique for assembling high-power laser diodes emitting at 808 and 980 nm was developed, which stably provides high radiation parameters when using one of the standard types of heat sinks for assembling high-power laser diodes, i.e., the C-mount. The maximum achievable power of laser diodes with a stripe contact width of 150 µm in the cw lasing mode was 25 W at a temperature of 20 °C.