腔内倾斜标准具法压缩KrF激光线宽的研究

我们对采用腔内倾斜标准具法压缩激光线宽进行了研究，较详细地讨论了影响线宽压缩效果的各种因素。并在一台长脉冲放电泵浦ＫｒＦ准分子激光器上，采用三个标准具作为线宽压缩元件，获得了线宽小于３ＧＨｚ，发散角近似衍射极限的高质ＫｒＦ激光输出。实验中研究了不同光阑孔径及输出耦合率对输出线宽和输出能量的影响。     

Nd：S—FAP晶体1.328μm激光特性研究

用染料激光和氙灯泵浦实现了ＮｄＳ－ＦＡＰ晶体低阈值、高效率的１．３２８μｍｍ激光运转。在透过率７％的平－平腔情况下，染料激光泵浦斜效率为３８％，阈值４．５ｍＪ，倍频红光波长为０．６６４μｍ，线宽１．３ｎｍ；采用氙灯泵浦（４×３０ｍｍ），实现了１．３２８μｍ自由运转，阈值为２４０ｍＪ，斜效率为０．８５％。测量了不同腔长，不同透过率情况的输出能量、光束发散角和偏振特性等。     

光栅腔BBO光参量振荡器

报道０．５３２μｍ泵浦的光栅腔ＢＢＯ光参量振荡器的实验研究结果，在１．０２－１．０８μｍ可调谐范围内，其输出线宽小于１ｎｍ，参量转换效率为３．５％。     

强反馈光纤光栅外腔半导体激光器

在理论上对强外腔反馈情形的半导体激光器线宽压窄效应进行了分析，对消反膜剩余反射率，外腔反射率，外腔腔长对线宽压缩的影响进行了研究，在实验上采用光纤光栅作为反馈元件，与一端镀有消反膜的１．５μｍ波段的常规多纵模交导体激光器耦合，构成强反馈光纤光栅外腔半导体激光器，得到单频窄线宽的激光输出，静态下边模抑制比大于３０ｄＢ，线宽小于１２０ｋＨｚ。     

XeF(C-A)蓝绿激光线宽压缩技术

利用表面放电光泵浦XeF(C-A)蓝绿激光器开展了激光线宽压缩技术研究,分别采用谐振腔腔镜谱带重叠法和光栅谐振腔法实现了线宽小于10 nm的窄线宽激光输出。采用谐振腔腔镜谱带重叠法,激光输出线宽约7 nm,采用光栅谐振腔法可以将激光线宽压缩到约1 nm,并实现XeF(C-A)激光的可调谐输出,调谐范围为470~495 nm。     

三种半导体阵列光谱组束结构的输出特性

基于光谱光束组合技术,利用光栅的衍射和外腔的反馈,并通过加入光束整形系统,将标准的半导体激光阵列的发光单元锁定在窄线宽的不同波长上,以近似平行光束沿组合方向输出,以实现半导体激光阵列输出光束质量的改善和线宽的压窄。实验中采用发光单元宽度100μm,周期500μm,由19个单元构成的标准阵列,分别对快、慢轴准直后光谱组束、光束整形后光谱组束和线宽压窄外腔组束进行了实验验证,实现了组合光束与单个发光单元近似的光束质量,同时得到了较窄的线宽输出,并对实验结果进行了分析。     

染料激光泵浦Nd：S—VAP晶体激光特性研究

实验测定了Ｎｄ：Ｓｒ５（ＶＯ４）３Ｆ晶体的吸收光谱特性；在５８３．０ｎｍ和８０９．０ｎｍ处有强的吸收峰。用可调谐染料激光作泵浦源，实现了低阈值、高效率的激光运转。在透射率１５％的平面平行腔情况下，斜率效率为５０％，阈值为２ｍＪ。倍频光中心滤长为５３６．０ｎｍ，线宽为１．４ｍｍ。本文还对Ｎｄ：Ｓ－ＶＡＰ晶体可作为ＬＤ泵浦的小型激光器的工作物质等问题进行了讨论。     

染料激光泵浦Nd：S－VAP晶体激光特性研究

实验测定了Ｎｄ：Ｓｒ５（ＶＯ４）３Ｆ（简称Ｎｄ：Ｓ－ＶＡＰ）晶体的吸收光谱特性；在５８３．０ｎｍ和８０９．０ｎｍ处有强的吸收峰。用可调谐染料激光作泵浦源，实现了低阈值、高效率的激光运转。在透射率１５％的平面平行腔情况下，斜率效率为５０％，阈值为２ｍＪ。倍频光中心波长为５３６．０ｎｍ，线宽为１．４ｍｍ。本文还对Ｎｄ：Ｓ－ＶＡＰ晶体可作为ＬＤ泵浦的小型激光器的工作物质等问题进行了讨论。     

喇曼自由电子激光振荡器

本文报道喇曼自由电子激光振荡器的研究结果。脉冲加速器电子束能量０．４ＭｅＶ，束流８００Ａ。采用满足布喇格条件的分布反馈谐振腔，取代传统的激光器反射镜。理论上进行了分析和设计，采用正弦形波结构选择振荡模式。喇曼自由电子激光振荡器实验表明，输出光谱显著变窄。频率分布半高宽度，超辐射下范围为７．５ｍｍ～９．２ｍｍ，分布腔下范围为８．６ｍｍ～８．９ｍｍ。     

成型压力对La0.7Sr0.3MnO3纳米固体内部缺陷结构影响的研究

应用溶胶凝胶法合成了平均尺寸为４０ｎｍ的Ｌａ０．７Ｓｒ０．３ＭｎＯ３纳米粉末，在０．２ＧＰａ到４．５ＧＰａ的压力范围内加压成型，制成＝６ｍｍ，厚为１ｍｍ的纳米固体样品。测量了不同成型压力下样品的正电子寿命谱，研究了纳米固体内部存在的三类空位缺陷随压力的变化规律。在低于１．０ＧＰａ的情况下，三类缺陷随压力的增加变化敏感，成型压力高于１．０ＧＰａ时，纳米固体内部的压致碎化导致十几个单空位尺寸大小的微孔洞缺陷数量的剧增，使纳米固体内部的缺陷密度增加，呈现反常的压力依赖关系。     

二极管泵浦Nd:LMA激光器的1054nm连续波输出

报道用一个3W激光二级管端面泵浦Nd:LMA激光器.实验采用三镜折叠象散补偿腔.在1054nm波长,激光器CW输出功率达230mW,斜率效率为38%,光-光转换效率9.5%.     

Highly selective terahertz optical frequency comb generator

Using a 10.5-GHz resonant electro-optic modulator placed inside a resonant optical cavity, we generated an optical frequency comb with a span wider than 3 THz. The optical resonator consists of three mirrors, with the output coupler being a thin Fabry-Perot cavity with a free spectral range of 2 THz and a finesse of 400. Tuning this filter cavity onto resonance with a particular high-order sideband permits efficient output coupling of the desired sideband power from the comb generator, while keeping all other sidebands inside for continued comb generation. This spectrally pure output light was then heterodyne detected by another laser with a frequency offset of the order of 1 THz.     

Experiment Research on a Highly Stable LD-pumped Solid State Laser

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Experiment Research on a Highly Stable LD-pumped Solid State Laser

In high power laser systems, the stability of the seed laser is vitally important. This paper presents the work on the design and manufacture of a highly stable LD pumped solid state seed laser which has the advantages of being all solid state, compact, easy to manufacture and low cost. The laser was composed of two parts. One was an LD pumped 0.5 mm thin Nd: YLF laser system in which the instability was around±6% (3σ). The other was a close-looped laser power control system using external cavity power feedback. Using an electro-optic modulator, a 1×2 optical fiber splitter and a signal processing circuit, we successfully realized the highly stable LD pumped Nd: YLF laser in which the instability of laser output power was lower than±0.2 %/hour (3σ). A digital PID (Proportion, Integration and Differentiation) control method was used with a control frequency of 40 kHz. The 3 mW of highly stable laser power through the optical fiber was obtained.     

All-fiber ring-cavity based frequency swept laser source for frequency domain OCT

<正>We develop a high-speed tunable,quasi-continuous-wave laser source for frequency domain(FD) optical coherence tomography(OCT).The laser resonance is realized within a unidirectional all-fiber ring cavity consisting of a fiber coupler,two fiber isolators,a semiconductor optical amplifier(SOA),and a fiber FabryPerot tunable filter(FFP-TF) for frequency tuning.Light output from the coupler is further amplified and spectral shaped by a booster SOA terminated at both ends with two isolators.The developed laser source provides up to 8000 sweeps per second over a full-width wavelength tuning range of 120 nm at center wavelength of 1320 nm with an average power of 9 mW,yielding an axial resolution of 13.6μm in air and a maximum sensitivity of about 112 dB for OCT imaging.The instantaneous linewidth is about 0.08 nm,enabling OCT imaging over an axial range of 3.4 mm in air.For optimization consideration based on this custom-built swept laser,experimental study on imaging quality relevant parameters of the swept laser with sine and ramp driving waveforms to the FFP-TF is conducted,and investigation of the swept laser on the cavity length is done.Implementing the laser source in our established swept source based OCT(SS-OCT) system,real-time structural imaging of biological tissue is demonstrated.     

Diode-pumped Pr(3+):KY(3)F(10) red laser

We report the first observation to our knowledge of room-temperature continuous-wave laser operation of a Pr(3+):KY(3)F(10) single crystal at 644.5 nm, pumped by a blue GaN laser diode emitting at 446 nm. With a 2.5% transmission output coupler and a nonoptimized optical cavity, an output power of 39 mW was obtained at 644.5 nm with a laser threshold of 125 mW and a differential slope efficiency of 23%.     

All-fiber single polarized Yb-doped fiber laser with a high extinction ratio

We present an all-fiber design for a single polarization Yb-doped fiber laser with all-fiber connections spliced. Single polarization with a high extinction ratio was achieved by the design of a laser cavity consisting of a fiber Bragg grating inscribed on a single-polarization fiber as a high reflective mirror and a piece of end-cleaved single-polarization fiber as an output coupler. The fiber laser operates at 1063.25 nm with an output power of 1.7 W, an optical signal- to-noise ratio of 70 dB and a narrow bandwidth of 54 pm. The laser output has a polarization extinction ratio of 700:1 or 28 dB, and a very stable power output.     

Compact high conversion efficiency Nd:YAG/LBO green laser using unstable V cavity

We demonstrated a 36.9 W green laser with an intra-cavity second harmonic generation. A compact unstable V type cavity was adopted to compress the whole cavity configuration. The type I phase-matching LiB₃O₅ was used as the nonlinear crystal in the second harmonic generation. The 36.9 W average power and 38 ns pulse width of 532 nm green laser was obtained at a repetition rate of 10.3 kHz, corresponding to a peak power of 94 kW. The optical to optical conversion efficiency from diode to green and from IR to green laser was about 19.8 and 82%, the whole cavity length is about 300 mm. To the best of our knowledge, this is the shortest cavity configuration of side pump green system with output power higher than 30 W and IR to green conversion efficiency larger than 80%. The output fluctuation of this system was less than 3% in 2 h.     

Laser performance of Nd:LaB3O6 cleavage microchips passively Q-switched with a Cr4+:YAG saturable absorber

Passively Q-switched laser oscillation at 1060 nm from an unprocessed Nd:LaB₃O₆ cleavage microchip with a Cr⁴⁺:YAG saturable absorber has been demonstrated. The influence of absorbed pump power, output coupler transmission and cavity length on the output pulse characteristics has been investigated. For a plano-concave cavity with a cavity length of 28 mm, pulse with 100 mW average output power, 4.0 μJ energy, 17 ns duration, 25 kHz repetition rate, and 0.24 kW, peak power was obtained at the absorbed pump power of 1.42 W and output coupler transmission of 3.5%. For a plano-plano cavity with a cavity length of 5 mm, pulse with 85 mW average output power, 2.1 μJ energy, 2.3 ns duration, 40 kHz repetition rate, and 0.89 kW, peak power was obtained at the absorbed pump power of 1.42 W and output coupler transmission of 5.6%. Because a chopper with a 5% duty cycle was employed in the experiments to reduce the influence of pump-induced thermal loading, the above average output powers were obtained at the 5% duty cycle and extrapolated to 100%.PACS 42.55.Rz; 42.60.Gd; 42.70.Hj     

Highly efficient and high output power of erbium doped fiber laser in a linear cavity configuration

A simple Erbium Doped Fiber Laser (EDFL) in linear cavity configuration is reported. The cavity design is based on an FBG as a back reflector, and a loop back optical circulator with an output coupler as the front reflector. Different coupling ratios of the coupler are tested and 50: 50 provides the highest coupling output power of 22.06 dBm (160.7 mW). The pump power conversion efficiency is about 95% when pumping with two pump lasers at 1460 and 1490 nm with combined pumping power of 545 mW. The laser output has a measured linewidth of 0.0179 nm.