角抽运Nd:YAG复合板条946 nm连续运转激光器

报道了一种适合中小功率输出的全固态激光器的角抽运方法, 抽运光从板条激光器中板条晶体的角部入射, 可获得较高的抽运效率和较好的抽运均匀性.采用单角抽运方式, 首次进行了角抽运Nd:YAG复合板条946 nm连续运转激光器的实验研究. 激光腔采用紧凑型平凹直腔结构, 腔长仅为20 mm. 当注入抽运功率为50 W时, 946 nm激光连续输出功率最高达5.29 W, 光光转换效率为10.6%, 斜效率为12%. 整台激光器结构紧凑, 调谐简单, 成本低, 具有广阔的应用前景. 关键词： 角抽运 Nd:YAG晶体 连续波 946 nm激光     

Nd:YAG laser pumped at 946 nm

A Nd:YAG laser crystal was pumped at 946 nm and lased at 1064 nm. This pump-lase format was investigated in order to reduce the quantum defect between the pump and laser photons as compared to other pump schemes of this material. To the best of our knowledge, this is the first realization of this scheme. A room temperature absorption coefficient and linewidth of approximately 0.075 cm(-1) and approximately 1 nm for 1% at. Nd(+3) concentrations were measured for the 946 nm absorption line. Those parameters impose both narrow-bandwidth pumping and a long absorption path. By increasing the laser crystal temperature above room temperature, the absorption cross sections at 946 and 938 nm increase due to enhanced thermal population of the upper energy level of the ground manifold. The possibility of exploiting this phenomenon to enhance the pump absorption is also discussed.     

Diode-pumped continuous-wave eye-safe Nd:YAG laser at 1415 nm

We describe the output performance of the 1415 nm emission in Nd:YAG in a plane-concave cavity under traditional pumping into the 4F5/2 level (808 nm) and direct in-band pumping into the 4F3/2 level (885 nm). An end-pumped Nd:YAG laser yielded maximum cw output power of 6.3 W and 4.2 W at 885 nm and 808 nm laser diode (LD) pumping, respectively. To the best of our knowledge, this is the highest output power of a LD-pumped 1415 nm laser.     

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.     

Diode-end-pumped linear-polarized single-frequency Tm:YAG laser at room temperature

By using two solid uncoated etalons, we present a diode-pumped linear-polarized single-frequency Tm:YAG laser operating at 2 μm. Placing one 0.1 mm F-P etalon at nearly Brewster angle in the cavity, the linear-polarization laser is achieved. The other 1 mm F-P etalon was turned in the range of very small angle, single-longitudinal-mode (SLM) could be obtained. The maximum output power of linear-polarized single-frequency laser of 60 mW is achieved at the wavelength of 2013 nm. The degree of the polarization is over 30 dB. Long-term frequency stability was also investigated, with the results of wavelength fluctuation about 2.55 × 10⁻¹³ m within 3 min and frequency change about 18.86 MHz, corresponding to a frequency stability of 1.27 × 10⁻⁷.     

A flashlamp-pumped 946 nm Nd:YAG laser

Generation of 946 nm radiation from a commercially available, flashlamp-pumped Nd:YAG laser was investigated. By suppression of the high-gain 1.064 m transition and with a specially designed cooling system, a stable emission at 946 nm was achieved in the temperature range 300–240 K. At a repetition rate of 10 Hz laser output powers of 100mW and 500 mW were obtained at room temperature and 240 K respectively. The temperature dependence of unsaturated gain, slope efficiency and pumping threshold were determined.S. Dimov is supported by a fellowship from the Alexander von Humboldt Foundation     

Properties of continuous-wave 1123 nm laser with diode-side-pumped Nd:YAG

Laser properties of diode-side-pumped Nd:YAG laser operating at 1123 nm are demonstrated. A 1.0 at % Nd-doped Nd:YAG rod with a size of Ø3 × 63 mm² is used as the active medium. Both radial and tangential thermal focal lengths of this side-pumped Nd:YAG rod are determined under lasing condition. The results show that the bifocusing strength of 1123 nm laser is larger than that of 1164 nm laser, and 1123-nm thermal focal lengths are shorter than those of 1064-nm laser due to higher quantum defect. Laser output performances of 1123 nm in terms of stability, output power and beam quality influenced by pump power at different cavity lengths are also discussed with a convex-piano cavity.     

Continuous-wave, 15.2 W diode-end-pumped Nd:YAG laser operating at 946 nm

A high-power continuous-wave (cw) Nd:YAG laser operating at 946 nm by utilizing a quasi-three-level transition is reported. The laser consists of a composite Nd:YAG rod end pumped by a fiber-coupled diode laser and a simple plane-concave cavity. At an incident pump power of 40.2 W, a maximum cw output of 15.2 W at 946 nm is obtained, achieving a slope efficiency of 45%. To the best of our knowledge, this is the highest output at 946 nm ever generated by diode-pumped Nd:YAG lasers. In addition, at an incident pump power of 15.2 W, a 1.25 W blue output at 473 nm is achieved with a simple compact three-element cavity and a type-I lithium triborate (LiB(3)O(5)) crystal as a frequency doubler.     

LD泵浦Nd:YAG 946 nm/1 064 nm双波长运转及腔内和频

用国产半导体激光二极管(LD)端面泵浦NdYAG晶体, 通过优化激光谐振腔反射膜系,调节1 064 nm谱线的线性损耗以达到与弱谱线946 nm的增益匹配,在室温下实现1 064 nm和946 nm双波长连续运转,并通过I类临界相位匹配LBO晶体腔内和频在国内首次实现500.8 nm青色激光连续输出.当泵浦注入功率为1.4W时和频青色激光最大输出达20 mW,光-光转换效率为1.4%,功率稳定性24 h内优于±3%.     

885 nm pumped,high efficiency single-frequency Nd:YAG ring laser

We report an efficient single-frequency ring laser pumped directly into emitting level by a fiber-coupled laser diode (FCLD) at 885 nm for the first time. 4.8 W laser at 1064 nm was obtained in a 0.7 at % Nd:YAG with 63% slope efficiency and 51.7% light-light efficiency in absorbed pump power. At the same time, the line width of the longitudinal mode was about 50 MHz, and the beam was nearly diffraction-limited with M2 ≈ 1.07.     

All solid-state continuous-wave Nd:YAG laser at 1319 and 659.5 nm under direct 885 nm pumping

The continuous-wave high efficiency laser emission of Nd:YAG at the fundamental wavelength of 1319 nm and its 659.5-nm second harmonic obtained by intracavity frequency doubling with an LBO nonlinear crystal is investigated under pumping by diode laser at 885 nm (on the ⁴ F _3/2 → ⁴ I _13/2 transition). An end-pumped Nd:YAG crystal yielded 9.1 W at 1319 nm of continuous-wave output power for 18.2 W of absorbed pump power. The slope efficiency with respect to the absorbed pump power is 0.55. Furthermore, 5.2 W 659.5 nm red light is acquired by frequency doubling, resulting in an optical-to-optical efficiency with respect to the absorbed pump power of 0.286. Comparative results obtained for the pump with diode laser at 808 nm (on the ⁴ F _5/2 → ⁴ I _13/2 transition) are given in order to prove the advantages of the 885 nm wavelength pumping.     

Diode-pumped continuous-wave Nd:YLF laser at 1313 nm

We present an efficiency Nd:LiYF₄ (Nd:YLF) laser operating at 1313 nm pumped directly into the emitting level ⁴ F _3/2. At the incident pump power of 10.3 W, as high as 3.1 W of continuous-wave output power at 1313 nm is achieved. The slope efficiency with respect to the incident pump power was 36.1%. To the best of our knowledge, this is the first demonstration of such a laser system. Comparative results obtained for the pump with diode laser at 806 nm, into the highly absorbing ⁴ F _5/2 level, are given in order to prove the advantages of the 880 nm wavelength pumping.     

Stable tunable single-frequency Nd:YAG laser

Single frequency operation of a Nd:YAG laser is obtained with a temperature-compensated, sealed intracavity etalon which is optimized with respect to selectivity and loss by taking spatial hole burning of the laser medium into account. For stabilization purposes we calculate the response of the laser when (i) the etalon's thickness is modulated and when (ii) the laser cavity length is modulated. We find orders of magnitude better stability for (i) and demonstrate the feasibility of a system with 100 mW output power, a longterm frequency stability of 3×10^?9, and an intensity stability of 10^?4.     

二极管泵浦1064nm单频Nd:YAG激光器输出功率稳定控制系统设计

介绍了激光二极管(LD)端面泵浦1064 nm单频Nd:YAG激光器的工作原理和结构特点,分析了影响这种固体激光器输出功率稳定性的主要因素,设计并实验研究了一种用于稳定该激光器输出功率的控制方案.该方案在严格控制LD和Nd:YAG晶体工作温度的条件下,当单频Nd:YAG激光器的输出功率波动时,根据LD输出功率与其注入电流成正比这一变化规律,利用获得的功率误差信号反馈控制LD的注入电流,即可稳定单频Nd:YAG激光器的输出功率.实验结果表明:当LD泵浦1064 nm单频Nd:YAG激光器的输出功率约为11.5 mW时,采用所设计的控制系统,可使激光输出功率稳定性在130 min内优于1.3%.     

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.     

100 W, single-frequency operation of an injection-locked Nd:YAG laser

We have built a single-frequency Nd:YAG laser capable of producing an output power of 101 W by injection locking a slave laser that can emit an output power of 121 W in the free-running state to a 2-W master laser. We confirmed that the output mode was diffraction limited and linearly polarized.     

Rotating-disk diode-pumped continuous-wave Nd:YAG laser

Continuous-Wave (CW) diode-laser-pumped experiments using rotating Nd: YAG disk(s) have been performed in the input-power range of 1–6 W and rotation-speed range of 0–25 Hz. With a single Nd: YAG disk in the laser cavity, about 1.56 W of output power at 1.06 µm due to the Nd³⁺ (⁴ F _3/2–⁴ I _11/2) transition at an absorbed input power of 4.2 W has been observed, leading to an optical-to-optical conversion efficiency of over 37% and slope efficiency of 52% using 7.5% transmission output coupler. The laser output power has been observed to decrease by either increasing the number of Nd:YAG disks in the cavity or increasing the rotation speed of the disk(s).     

Electro-optically Q-switched 946 nm laser of a composite Nd:YAG crystal

A depolarization phenomenon in an electro-optical crystal in a quasi-three-level 946 nm Nd:YAG laser is observed. A compensation of the thermal effects in electro-optical crystals is achieved by employing a quarter-wave plate, with one optical axis parallel to the laser polarization. This technique allows for the production of an electro-optically Q-switched 946 nm Nd:YAG laser at 1 k Hz. A maximum output power of 350 m W at 1 k Hz repetition frequency and 11 ns pulse duration are achieved with an output coupler of 10% transmission under the incident pump power of 11.1 W, corresponding to a peak power of ～32 k W.     

An efficient high-power 946 nm Nd:YAG planar waveguide laser

To date increasing the output power of Nd:YAG lasers operating on the three-level ⁴F_3/2→⁴I_9/2 transition has been restricted by detrimental thermal effects in the gain medium. Using a double-clad planar waveguide, an efficient 946 nm laser has been demonstrated that produced 35 W of output power with corresponding slope and optical-to-optical conversion efficiencies of 56% and 50%, respectively. Performance and further power-scaling possibilities are discussed.     

Linear polarization output performance of Nd:YAG laser at 946 nm considering the energy-transfer upconversion

A theoretical model of quasi-three-level laser system is developed, in which both the thermally induced depolarization loss and the effect of energy-transfer upconversion are taken into account. Based on the theoretical investigation of the influences of output transmission and incident pump power on thermally induced depolarization loss, the output performance of 946 nm linearly polarized Nd:YAG laser is experimentally studied. By optimizing the transmission of output coupler,a 946 nm linearly polarized continuous-wave single-transverse-mode laser with an output power of 4.2 W and an optical–optical conversion efficiency of 16.8% is obtained, and the measured beam quality factors are M_x~2= 1.13 and M_y~2= 1.21.The theoretical prediction is in good agreement with the experimental result.