Efficient, scalable, internally folded Nd:YAG laser end-pumped bylaser diodes

A scalable diode-pumped Nd:YAG laser is described in which the gain element resembles a penta-prism. This design allows longitudinal pumping along five separate axes. Using five high-power single stripe laser diodes, 4.16 W of absorbed power produced 2.3 W CW at 1.06 μm. The slope efficiency was 56%, the output was plane polarized, and the laser operated in the TEM₀₀ mode. The threshold power, was 48 mW. No evidence of thermal saturation was observed up to the maximum pump power. With an intracavity KTP crystal, 431 mW of CW amplitude-stable output at 532 nm was generated. Repetitive Q-switched operation is also reported     

Frequency-stabilized diode-pumped Nd:YAG laser of high power

We describe a frequency-stabilized diode-pumped Nd:YAG laser of high power whose single-mode operation is obtained by suppressing the spatial hole burning through the twisted-mode technique. Active frequency stabilization is achieved by fringe side locking the laser beam to a reference Fabry-Perot cavity. Output power up to 800 mW in single-transverse and -longitudinal mode operation with a linewidth of less than 20 kHz is obtained     

半导体激光泵浦Nd:YAG激光器技术研究

本文研究了半导体激光端面泵浦固体激光器中的主要技术,指出泵浦功率较低时,为了降低激光器的阈值应选用近半共心腔或大R腔;泵浦功率较高时,为了提高激光器的输出功率和转换效率应选用半共焦腔。泵浦光耦合系统的设计应满足与激光腔模的最佳模式匹配。当泵浦功率为86mW时,Nd;YAG激光器基模输出8.3mW;激光器阈值为12mW。     

二极管泵浦Nd:YAG/LBO连续波蓝光激光器

报道了一种半导体二极管(LD)泵浦Nd：YAG晶体,LBO腔内倍频实现了稳定的连续波473hm蓝光激光器,采用简单、结构紧凑的平凹腔设计,当注入功率为17W时,单向获得了234mW的单模蓝光输出。     

Tunable single- and double-frequency diode-pumped Nd:YAG lasers

An Nd:YAG 1-cm-long crystal has been used as the active medium for tunable single- and double-frequency lasers with a metallic absorbing thin-film selector. Cobalt and chromium thin films (210-nm thickness) were used for mode number and frequency control. The laser with a short cavity (25 mm) provided slow smooth tuning up to 6 GHz, the frequency chirp up to 4 GHz with repetition rate about 0.5 kHz and hop tuning over 150 GHz at a maximum pump power of 1.8 W. 520 mW of single-frequency output power was achieved. Double-frequency operation with a space of 1.5-2.5 GHz was realized in a laser with cavity length up to 100 mm     

Nd：YAG激光治疗分泌性中耳炎

用Ｎｄ：ＹＡＧ激光在鼓膜前方造孔，孔径２～３ｍｍ，多数病例听力改善在半年内未再出现中耳积液。激光治疗分泌性中耳炎具有显效、简单、安全，易于推广的实用价值。     

激光二极管抽运Nd:YAG双薄片激光器

激光介质的热效应是高平均功率固体激光器面临的最大挑战,采用薄片激光介质是解决热效应的有效手段之一。当在抽运区尺寸远大于薄片厚度并且抽运光均匀分布的条件下,热流近似为沿厚度方向的一维分布,从而大大降低介质的热透镜效应和热致应力双折射。设计了四通光学耦合系统,通过提高二极管激光器阵列输出激光强度分布的均匀性,并优化经微柱透镜准直后光束的发散角,实现了抽运光的近平顶分布。采用两片1 mm厚的Nd∶YAG薄片激光介质,在两个峰值功率2000 W,占空比为15%的二极管激光器阵列抽运下,获得了峰值功率1440 W,平均功率216 W的准连续激光输出,光光转换效率达到36%,电光转换效率超过16%,在稳腔下测得的光束质量M2 因子约为12×13。     

115-W Tm:YAG diode-pumped solid-state laser

A compact diode-pumped Tm:YAG laser capable of generating greater than 100 W of CW power at 2 μm has been demonstrated. A scalable diode end-pumping architecture is used in which 805-nm radiation, coupled to the wing of the Tm³⁺³H₆-³H ₄ absorption feature, is delivered to the end of the laser rod via a lens duct. To facilitate thermal management, undoped YAG end caps are diffusion bonded to the central doped portion of the laser rod. For 2% and 4% Tm-doped rods of the same length, the lower doping level results in higher power, indicating that cross relaxation is still efficient while offering lower thermal stress and reduced absorption at the laser wavelength. Output powers for various output coupler reflectivities are compared to the predictions of a quasi-three-level model. Thermal lensing, cavity stability, and stress-induced birefringence measurements are described. The beam quality was analyzed with the 2% Tm-doped rod and a flat output coupler, yielding M² values of 14-23     

Frequency noise measurement of diode-pumped Nd:YAG ring lasers

The combined frequency noise spectrum of two lightwave Model 120-01A nonplanar ring oscillator lasers was measured by first heterodyne detecting the IF signal and then measuring the IF frequency noise using an RF frequency discriminator. The results indicated the presence of a 1/f² noise component in the power spectral density of the frequency fluctuations between 1 Hz and 1 kHz. After incorporating this 1/f² into the analysis of the optical phase tracking loop, the measured phase error variance closely matches the theoretical predictions     

激光二极管泵浦的调Q Nd：YAG激光器的理论研究

本文主要从理论上分析了ＤＰＬ调Ｑ激光器的动态特性，并对电光调Ｑ与声光调Ｑ激光器的输出特性进行了比较．     

Single-mode operation of diode-pumped Nd:YAG lasers by pump-beamfocusing

We present a theoretical study of the maximum single frequency power that can be obtained from a simple coaxially end-pumped Nd:YAG laser. The approach is general for four-level solid-state laser systems. It is shown that careful control of the pump beam geometry, cavity length, and crystal length can enhance single frequency performance     

Characteristics of an erbium-doped fiber amplifier pumped by a frequency doubled diode-pumped Nd:YAG laser

The characteristics of an erbium-doped fiber amplifier pumped by a 532-nm diode-pumped Nd:YAG laser are presented. A maximum system gain of 31 dB at 591 Mb/s is obtained with a corresponding system noise of less than 0.5 dB. An amplified signal output power of greater than 10 mW was obtained, with a coupled pump power of 46 mW and a corresponding quantum efficiency of around 65%. By optimizing the erbium fiber design, higher system gains and saturation power levels are feasible. These figures, and in particular the combination of high output powers and low noise, establish the usefulness of this pump laser as a viable alternative to the semiconductor pump lasers currently under investigation at 1480 and 980 nm.<>     

Generation of blue light at 469 nm by efficient frequency doublingof diode-pumped Nd:YAG laser

Efficient operation of a diode-pumped Nd:YAG laser at 938.5 nm is reported. A continuous wave output power of 3.9 W is obtained. Single-pass frequency doubling in periodically poled KTiOPO₄ (KTP) delivered a power of 88 mW at 469 nm. By intracavity frequency doubling an output of 200 mW in the blue region is achieved     

Measurements of heating and energy storage in diode-pumped Nd:YAG

Two experiments were carried out to measure the stored energy and heat deposited in the laser medium and to determine the heat parameter χ, defined as the heat deposited per unit of stored energy. The stored energy was calculated from small-signal gain measurements. The heat deposition was calculated from interferometric measurements of the thermally induced optical path length changes of the laser rod under test. χ is to be 1.1 in a 200-μs pump pulse, about one-third of the value obtained for flashpumped Nd:YAG. Without fluorescence decay, χ is 0.7     

Two-frequency injection-seeded Nd:YAG laser

Dual longitudinal mode (DLM) operation of a Nd:YAG laser is achieved by simultaneously injection seeding with two seed frequencies. We show that the relative energy in the two frequency components can be adjusted by varying the relative seed power, and that they have excellent spatial, angular, and temporal overlap. The result is a deeply modulated 1.06-μm pulse with a modulation frequency that can be tuned from 185 MHz to at least 17 GHz in 185 MHz increments. In addition to the two seeded frequencies, weak sidebands are also observed in the output spectra. Their energy content is typically less than 1% of that of the seeded modes. We discuss mechanisms which might cause them     

Single-diode end-pumped Nd:YAG laser

Experimental results on the first miniature Nd:YAG laser end-pumped by a single incoherent infrared-emitting diode are given. Laser operation was verified by measurements of relaxation oscillations, angular divergence, wavelength, and nonlinear output. In order to emit in the 0.81- μm pump band of Nd:YAG, the GaAs1-xPxdiode required cooling to 88 K (-185°C). Cooling the diode increased its efficiency while cooling the rod decreased the pump power necessary to reach threshold. With both laser mirrors highly reflecting at 1.06 μm, the maximum pulse powerP_{D}^{th}emitted by the diode at threshold was 6.2 ± 1.2 mW. The diode power required for laser threshold at room temperature was derived and compared with more recent experiments. Miniature size and long-lived solid-state components make this laser attractive for further development.     

二极管端泵浦Nd：YAG连续激光器

我们研制了一台二极管连续端泵浦的Ｎｄ：ＹＡＧ激光器，用国产激光二极管作泵浦源，泵浦激光波长为０．８０８μｍ。激光介质为φ５×５ｍｍ的Ｎｄ：ＹＡＧ棒，输出激光波长为１．０６μｍ，用ＣＣＤ相机和图象处理系统记录和分析激光光斑，得到激光横模为ＴＥＭ００模，当输入谐振腔的泵浦功率为２２５ｍＷ时，输出连续激光功率最高达７６．４ｍＷ，光－光转移效率为３３．９％，电光斜效率达到９．１％，并做了腔外倍频实验。     

162 W激光二极管抽运Nd:YAG腔内倍频激光器

根据激光介质的热透镜焦距及其随抽运功率的变化，设计了大模体积高准直稳定性谐振腔以获得较大的模体积．同时使谐振腔对热焦距的变化和机械对准的扰动不灵敏。这种设计可以提高激光器的效率和稳定性．并且使输出激光具有较好的光束质量。采用双声光Q开关提高关断功率，在输出功率1250W的连续激光二极管阵列抽运下，获得了210w的调Q激光输出。采用工作温度80℃的Ⅱ类匹配KTP晶体，以避免KTP晶体的灰色轨迹效应，对KTP晶体采用半导体温控系统控温．在重复频率10kHz时获得了162W的调Q绿光输出，光一光转换效率达到13％，脉宽约为80ns．光束质量M^2因子约为20。     

Nd:YAG laser pumped infrared dye laser

Efficient operation of a high peak power and high-average power infrared dye laser, continuously tunable over the range of 10810-12160 Å, has been achieved by pumping with an Nd:YAG laser. A peak power as high as 4 MW with an average power of 390 MW was obtained.