2-W Ho:YAG laser intracavity pumped by a diode-pumped Tm:YAG laser

Efficient room-temperature operation of a Ho:YAG laser, intracavity pumped by a diode-bar-pumped Tm:YAG laser, is reported. At rod mount temperatures of 10 degrees C, for both the Tm:YAG and the Ho:YAG rods, we obtained 2.1 W of output at 2.097mum from the Ho:YAG laser for 9.2 W of diode power incident upon the Tm:YAG rod.     

Short-term frequency characteristics of 2 µm single frequency Solid-state lasers

The Short term frequency stability characteristics of 2 μm single frequency Solid-state lasers was investigated. The two laser systems of 2 μm single longitudinal mode oscillation Tm, Ho:YLF microchip laser and Ho:YAG NPRO laser were designed and constructed. The Short term frequency stability of these two laser were measured with the fiber delay self-beating heterodyne method. The 3dB width of the relative frequency fluctuation of Tm, Ho:YLF microchip laser and Ho:YAG NPRO laser were measured to be 895 and 736 Hz with 500 m fiber optical (2.5 μs delay). The proportional relation between the lasing fluctuation and the delay time were 358 and 263 Hz/μs, respectively. The vibration experiment was presented and it indicated that the NPRO Ho:YAG was more terrible to the influence of vibration, which is important in the practical application of wind measurement lidar.     

6.1 W single frequency laser output at 1645 nm from a resonantly pumped Er:YAG nonplanar ring oscillator

A monolithic 1645 nm Er:YAG nonplanar ring oscillator (NPRO) resonantly pumped by a 1532 nm fiber laser is demonstrated. For reducing the energy-transfer upconversion effect, a 0.5% doped Er:YAG nonplanar crystal was used. An up to 6.1 W single frequency laser output at 1645 nm was obtained, with a slope efficiency of 55.2% and an optical efficiency of 48.0%. The linewidth of the Er:YAG NPRO was 14.4 kHz.     

In-band pumped highly efficient Ho:YAG ceramic laser with 21 W output power at 2097 nm

We report on the high-power and high-efficiency operation of a polycrystalline Ho:YAG ceramic laser in-band pumped by a Tm fiber laser at ~1907 nm. Lasing characteristics of a 1.5 at.% and a 2.0 at.% Ho3?-doped YAG ceramic were investigated and compared. Using an output coupler of 6% transmission, over 21.4 W of cw output power at 2097 nm has been generated with the 1.5 at.% doped Ho:YAG ceramic under 35 W of incident pump power, corresponding to an average slope efficiency with respect to the incident pump power of 63.6% and an optical-to-optical conversion efficiency of 61.1%.     

Efficient single-axial-mode operation of a Ho:YAG ring laser pumped by a Tm-doped silica fiber laser

Efficient single-frequency operation of a Ho:YAG ring laser at room temperature with a traveling-wave TeO2 acousto-optic modulator to enforce unidirectional operation is reported. By use of a 2-at. % Ho3+-doped 10-mm-long Ho:YAG rod, end pumped by a cladding-pumped tunable Tm-doped silica fiber operating at 1.9 microm, the Ho:YAG ring laser yielded 3.7 W of single-frequency output at 2.1 microm in a diffraction-limited TEM00 beam with M2 < 1.1 for an incident pump power of 8.8 W. The rf power required for unidirectional operation was 0.3 W and corresponded to an increase in cavity loss for the lasing direction (due to diffraction) of only 0.5%. The prospects for further improvement in efficiency are discussed.     

Efficient grating-tuned mid-infrared Cr2+:CdSe laser

Room-temperature, all-solid-state, broadly tunable laser operation of Cr(2+) -doped CdSe has been demonstrated. Pumping with a Q -switched Tm, Ho:YLF laser running at a 1-kHz repetition rate achieved broadband output of 500 mW at 2.6mum with 48% absorbed power slope efficiency. With reduced efficiency, as much as 815 mW of power was obtained. With a diffraction grating, the Cr(2+): CdSe laser was tuned from 2.3 to 2.9mum with 10-nm bandwidth (FWHM) and output power up to 350 mW.     

Continuous-wave operation of a room-temperature Tm: YAP-pumped Ho: YAG laser

We report a continuous-wave (CW) 2.1-μm Ho:YAG laser operating at room temperature pumped by a diode-pumped 1.94-?m Tm:YAP laser.The maximum output power of 1.5 W is obtained from Ho:YAG laser,corresponding to Tm-to-Ho slope efficiency of 17.9% and diode-to-He conversion efficiency of 5.6%.     

Laser-diode-pumped 1319-nm monolithic non-planar ring single-frequency laser

Single-frequency 1319-nm laser was obtained by using a laser-diode-pumped monolithic Nd:YAG crystal with a non-planar ring oscillator (NPRO). When the NPRO laser was pumped by an 800-μm fiber coupled laser diode, the output power of the single-frequency 1319-nm laser was 220 mW, and the slope efficiency was 16%. With a 100-μm fiber coupled diode laser pumped, 99-mW single-frequency 1319-nm laser was obtained with a slope efficiency of 29%.     

Single-frequency, Q-switched Ho:YAG laser at room temperature injection-seeded by two F-P etalons-restricted Tm, Ho:YAG laser

We demonstrated a 1.91 μm pumped, injection-seeded Q-switched Ho:YAG laser operating at room temperature. By inserting two Fabry-Perot etalons into the laser cavity, single-frequency Tm, Ho:YAG seed lasing was achieved at a wavelength of 2090.9 nm, with a typical output power of 60 mW. Single-frequency, nearly transform-limited Q-switched operation of the Ho:YAG laser was achieved by injection seeding. The output energy of the single-frequency Q-switched pulse is 7.6 mJ, with a pulse width of 132 ns and a repetition rate of 100 Hz. We measured the pulse spectrum, half-width of which was 3.5 MHz, by a heterodyne technique.     

A Tm:YLF End-Pumped Acousto-Optic <Emphasis Type="Italic">Q</Emphasis>-Switched Ho:YAG Laser

We report an acoustic Q-switched Ho:YAG laser end-pumped by a 1,908 nm Tm:YLF laser. The doping concentration of Ho:YAG crystal is 2 at.%, and dimensions ø5×20 mm. We measure the pulsedlaser output characteristics of the Ho:YAG laser at different repetition rates (RF). Under optimum experimental conditions, the high-power 2.1 μm output power reaches 4.17 W at a given pump power of 13.25 W and repetition frequency of 8.0 kHz. For a slope efficiency of 16.88%, the corresponding optical-to-optical conversion efficiency reaches 31.47%. We obtain a minimum single pulsed energy of 7.36 mJ and a pulse width of 52.8 ns at a pump power of 10.52 W and repetition rate of 0.5 kHz, with a peak power of 139 kW.     

Injection-locked single-frequency laser with an output power of?220?W

A solid-state laser system for the next generation of gravitational wave detectors with an output power of 220?W at the wavelength of 1064?nm is presented. Single-frequency operation of the laser was achieved by injection-locking of a high-power ring oscillator to an amplified non-planar ring oscillator (NPRO) following the Pound?CDrever?CHall scheme. The high-power stage which features four longitudinally pumped Nd:YAG laser crystals as active media in a ring resonator configuration was designed for reliable long term operation. Using a non-confocal ring cavity to filter the output beam, a pure TEM₀₀ mode with 168 W output power was obtained.     

Ho:YAG laser intracavity pumped by a diode-pumped Tm:YLF laser

We report a compact Ho:YAG laser that is intracavity pumped by a diode-pumped Tm:YLF laser. Both lasers exhibit pulse mode behavior. Operating both crystals at room temperature (25 degrees C), we obtained 1.6 W of average output at 2.09 microm from the Ho:YAG laser for 15.4 W of diode power incident upon the Tm:YLF rod and a slope efficiency of 21%.     

高功率Cr,Tm,Ho∶YAG激光器的实验研究

在医学应用上,Cr,Tm,Ho∶YAG激光器需要在大功率、高重频下工作。合理的设计对提高Cr,Tm,Ho∶YAG激光器的输出功率是很重要的。通过对Cr,Tm,Ho∶YAG输出特性进行理论分析和实验验证可知,腔长、全反射镜曲率半径、输出镜透过率、水温等因素对Cr,Tm,Ho∶YAG激光器的输出功率均有影响。提出了优化设计Cr,Tm,Ho∶YAG激光器的方法。在镀银腔情况下,当重频为10Hz时,激光阈值为45J,斜效率为1.1%;当输入能量为121J时,输出的平均功率为9.7W。在陶瓷聚光腔情况下,当重频为10Hz时,激光阈值为40J,斜效率为2.7%;当输入能量为100J时,输出的平均功率为16.2W。     

An Ho:YAG Laser with Double-Pass Pumping and the ZnGeP2 OPO Pumped by the Ho:YAG Laser

We report an efficient Ho:YAG laser end pumped by Tm:YLF lasers with double-pass pumping. We achieve the maximum continuous wave (CW) output power of 46.0 W with a single-pass pumping and 50.2 W with a double-pass pumping, corresponding to a slope efficiency of 58.0% and 62.8%, respectively. In addition, we use the Ho:YAG laser as a pumping source of the ZnGeP₃ optical parametric oscillator (OPO) and obtain the maximum average output power of 14.2 W with a linear cavity and 17.0 W with a ring resonator, respectively.     

Directly diode-pumped high-energy Ho:YAG oscillator

We report on the high-energy laser operation of an Ho:YAG oscillator resonantly pumped by a GaSb-based laser diode stack at 1.9 μm. The output energy was extracted from a compact plano-concave acousto-optically Q-switched resonator optimized for low repetition rates. Operating at 100 Hz, pulse energies exceeding 30 mJ at a wavelength of 2.09 μm were obtained. The corresponding pulse duration at the highest pump power was 100 ns, leading to a maximum peak power above 300 kW. Different pulse repetition rates and output coupling transmissions of the Ho:YAG resonator were studied. In addition, intracavity laser-induced damage threshold measurements are discussed.     

Frequency stabilization of a monolithic Nd:YAG ring laser by controlling the power of the laser-diode pump source

The frequency of a 700-mW monolithic nonplanar Nd:YAG ring laser (NPRO) depends, with a large coupling coefficient (megahertz per milliwatt), on the power of its laser-diode pump source. Using this effect, we demonstrate frequency stabilization of a NPRO to a frequency reference by feeding back to the current of its pump diodes. We achieved an error-point frequency noise smaller than 1mHz/ radicalHz and, simultaneously, a reduction of the power noise of the NPRO by 10 dB without an additional power-stabilization feedback system.     

Efficient high-power Ho:YAG laser directly in-band pumped by a GaSb-based laser diode stack at 1.9 μm

An efficient high-power Ho:YAG laser directly in-band pumped by a recently developed GaSb-based laser diode stack at 1.9 μm is demonstrated. At room temperature a maximum continuous wave output power of 55 W at 2.122 μm and a slope efficiency of 62% with respect to the incident pump power were achieved. For narrow linewidth laser operation a volume Bragg grating was used as output coupler. In wavelength stabilized operation a maximum output power of 18 W at 2.096 μm and a slope efficiency of 30% were obtained. In this case the linewidth is reduced from 1.2 nm to below 0.1 nm. Also spectroscopic properties of Ho:YAG crystals at room temperature are presented.     

Development of a Single-Longitudinal-Mode Ho:YAG Laser Based on Corner Cube

We present a Tm-doped fiber laser pumped Fabry-Perot etalons Ho:YAG laser based on a corner cube.A maximum single-longitudinal-mode and fundamental transverse mode output power of 478 mW at the waveiength of 2091.06 nm is achieved with a pump power of 16.3 W,corresponding to an opticai-to-optical efficiency of 2.9%and a slope efficiency of 7.9%.The single-longitudinal-mode and fundamental transverse mode are less sensitive to the rotating of the corner cube.The results indicate the potential impact of a single-longitudinal-mode Ho:YAG laser with corner cube geometry to improve the anti-maladjustment stability.     

103 W in-band dual-end-pumped Ho:YAG laser

An efficient 2?μm in-band pumped Ho:YAG laser was demonstrated. The resonator involves two Ho:YAG crystals, each of which was dual-end-pumped by two orthogonally polarized diode-pumped Tm:YLF lasers. The maximum continuous wave output power of 103?W was achieved, corresponding to a slope efficiency of 67.8% with respect to the incident pump power and an optical-to-optical conversion efficiency of 63.5%. Under Q-switched mode, we obtained 101?W laser output at 30?kHz, corresponding to a slope efficiency of 66.2%. The beam quality or M² factor was found to be less than 2.     

LD抽运Cr,Tm,Ho∶YAG微片激光器单纵模运转特性的研究

研究了LD抽运的单纵模Cr,Tm,Ho∶YAG微片激光器,激光器厚度为1?mm,在用波长785?nm的LD进行端面抽运时,激光器阈值为1060?mW,单纵模激光最大输出功率为31?mW. 对激光器输出功率随温度变化特性进行了研究,验证了CTH∶YAG晶体的温度敏感性. 还研究了激光器的温度调谐特性,实验测得激光器的温度调谐系数为14?GHz/℃. 关键词： 激光光学 CTH∶YAG微片激光器 LD抽运 单纵模运转