Diode-end-pumped Tm,Ho:YVO<Subscript>4</Subscript> microchip laser at room temperature

Room temperature Tm, Ho:YVO₄ microchip laser operated around 2 μm was demonstrated for the first time to our knowledge. At a heat sink temperature of 283 K, a maximum output power of 47 mW was obtained by using a 0.25 mm length crystal at an absorbed pump power of 912 mW, corresponding to a slope efficiency of 9.1%. Increasing the temperature to 288 K, as much as 16.5 mW 2052.3 nm single-longitudinal-mode laser was achieved. The M ² factor was measured to be 1.4.     

A comparative study on diode-pumped single-frequency Tm:YAG and Tm:GdVO<Subscript>4</Subscript> lasers

In this paper, we present experimental results concerning on the laser characteristics of Tm:YAG laser and Tm: GdVO₄ laser. At room temperature, the maximum output power of Tm:YAG laser and Tm:GdVO₄ laser is 210 and 145 mW, respectively. High efficiency can be achieved for both lasers at room temperature. Nevertheless, compared with Tm:GdVO₄ laser, Tm:YAG laser can operate on single frequency with high power easily. As much as 60 mW of 2013.9 nm single-longitudinal-mode (SLM) laser was achieved for Tm:YAG laser. For Tm:GdVO₄ laser 51 mW of 1919.7 nm SLM laser was achieved. The SLM Tm:YAG laser is better for using as a seed laser for coherent wind measurements and differential absorption LIDAR systems.     

2041.3 nm/2054.6 nm simultaneous dual-wavelength single-longitudinal-mode Tm,Ho:YVO<Subscript>4</Subscript> microchip laser

We report a single-longitudinal-mode CW diode-pumped Tm, Ho: YVO₄ microchip laser emitting at both 2041.3 and 2054.6 nm. At each wavelength, the laser has a single longitudinal mode. The total single-longitudinal-mode output power reaches 185 mW with 20.4% optical conversion efficiency at 905 mW incident pump power.     

Single-longitudinal-mode lasing of Tm,Ho:GdVO<Subscript>4</Subscript> using a filter of Fabry-Perot etalon and volume Bragg grating

In this letter, we report a diodepumped CW Tm, Ho:GdVO₄ laser at 77 K with a volume Bragg grating (VBG) instead of the conventional mirror. Inserting a Fabry-Perot etalon into the cavity, a singlelon-gitudinal-mode of Tm, Ho:GdVO₄ laser which I s operating at 2038.387 nm with output power 64 mW is obtained. The slope efficiency of 4.68% and a narrow linewidth about 45 pm FWHM are achieved. And appropriate cavity length is about 75 ± 5 mm.     

Diode-pumped Tm:GdVO<Subscript>4</Subscript> lasers with double etalons

Diode end-pumped single-frequency Tm:GdVO₄ laser at room temperature was reported. The maximal output power of single-frequency is as high as 51 mW by using two uncoated fused YAG etalons, which are respectively 0.05 mm thick and 1 mm thick. We obtained the single frequency Tm:GdVO₄ laser at 1919.7 nm. The slope efficiency is 1.4%. The single-longitudinal-mode (SLM) laser can be used as a seed laser for coherent wind measurements and differential absorption LIDAR systems.     

Room temperature diode-pumped 1875.1 nm Tm:GdVO<Subscript>4</Subscript> laser

A diode end-pumped single-frequency Tm:GdVO₄ laser at room temperature was reported. The maximal output power of single-frequency is as high as 66 mW by using two uncoated fused etalons, which are respectively 0.05 mm thick YAG and 1 mm thick quartz. We obtained the single frequency Tm:GdVO₄ laser at 1875.1 nm. The slope efficiency is 1.5%. The change of the lasing wavelength on temperature was also measured. The single-longitudinal-mode (SLM) laser can be used as a seed laser for coherent wind measurements and differential absorption LIDAR systems.     

diode-pumped single-frequency Tm:GdVO<Subscript>4</Subscript> laser at 1897.6 nm

A diode end-pumped Tm:GdVO₄ laser at room temperature is reported. The maximal output power of single-frequency is as high as 34 mW by using two uncoated fused etalons, which are respectively 0.05 mm thick YAG and 1mm thick quartz. We obtained the single frequency Tm:GdVO₄ laser at 1897.6 nm with the slope efficiency of 1.3%. The single-longitudinal-mode (SLM) laser can be used as a seed laser for coherent wind measurements and differential absorption LIDAR systems.     

Laser spectrum of a high power Tm,Ho:GdVO<Subscript>4</Subscript> laser

In this paper, we report a 18.8 W continuous wave and 18.4 W Q-switched diode-pumped cryogenic Tm(5 at %), Ho(0.5 at %):GdVO₄ laser. The pumping source of Tm, Ho:GdVO₄ laser is a fiber-coupled laser diode with fiber core diameter of 0.4 mm, supplying 42 W power at 802.5 nm. For input pump power of 41.9 W at 802.4 nm, the output power of 18.8 W in CW operation, optical-to-optical conversion efficiency of 45% at 2.05 μm and the average output power of 18.4 W in Q-switched operation, optical-to-optical conversion efficiency of 44% at 2.04 and 2.05 μm have been attained. The emission wavelengths of the Tm(5 at %), Ho(0.5 at %):GdVO₄ laser were firstly compared when it worked in CW mode and Q-switched mode.     

A high power CW Ho,Tm:GdVO<Subscript>4</Subscript> laser

In this paper, we report a 22.7 W continuous wave (CW) diode-pumped cryogenic Ho( at %), Tm(3 at %):GdVO₄ laser. The pumping sources of Ho,Tm:GdVO₄ laser are two fiber-coupled laser diodes with fiber core diameter of 0.4 mm, both of them can supply 42 W power laser operating near 802 nm. For input pump power of 64.7 W at 802.5 nm, the output power of 22.7 W in CW operation, optical-to-optical conversion efficiency of 35.1% at 2.05 μm has been attained. The M ² factor was found to be 2.0 under an output power of 16.5 W.     

A single-longitudinal-mode CW 0.25 mm Tm,Ho:GdVO<Subscript>4</Subscript> Microchip Laser

A single-longitudinal-mode of 0.25 mm Tm,Ho:GdVO₄ Microchip Laser was reported. The maximal continuous wave (CW) output power was 26.4 mW and the threshold of 118 mW. The Tm,Ho:GdVO₄ Microchip Laser output wavelength was centered at 2039.7598 nm with bandwidth of about 57.1 pm. The beam quality factor was M ² ∼ 1.52 ± 0.03 measured by knife-edge method. The Longitudinal-Mode was scanned by a FPI and the transverse mode was monitored by an infrared vidicon camera.     

A Single-Longitudinal-Mode Dual-Wavelength cw Tm,Ho:GdVO4 Microchip Laser

A liquid nitrogen cooled dual-wavelength Tm,Ho：GdVO4 microchip laser is reported. The output dual wavelengths axe at 2038.9nm and 2050.1 nm. At each wavelength, the laser has a single longitudinal mode. The threshold power is nearly 20mW and the slope efficiency is 18.7%. The single longitudinal mode output power reaches 98mW, and the ratio of power is about 60% （2038.9nm） and 40% （2050.1 nm）.     

Research of Tm (5.5 at %), Ho (0.55 at %):GdVO<Subscript>4</Subscript> laser pumped by diode laser at 800 nm

In this paper, we report a Tm (5.5 at %), Ho (0.55 at %):GdVO₄ laser pumped by diode laser at 800 nm. To our best knowledge, it is the first time that the use of Tm (5.5 at %), Ho (0.55 at %):GdVO₄ crystal among the similar experiments. We observed the influences of LD working temperature i.e. pump wavelength to 2 μm laser conversion efficiency. In the conditions of the continuous wave and 10 kHz acousto-optic Q-switch, high efficiency output of 2.05 μm laser was obtained. With the maximum pump power of 34.6, 13.9, and 13.6 W at 2.05 μm laser output was achieved respectively. Single laser pulse width was 25.6 ns in 10 kHz acousto-optic Q-switched condition.     

Single-longitudinal mode Nd:YVO<Subscript>4</Subscript>/YVO<Subscript>4</Subscript>/KTP green solid state laser

We present the concept and practical realization of a single frequency, tuneable diode pumped Nd:YVO₄/YVO₄/KTP microchip laser operating at 532 nm. Theoretical analysis of the single mode operation of such a laser configuration is presented. The single frequency operation has been obtained in a birefringent filter, where an YVO₄ beam displacer acts as an ideal polarizer. Experimental results are in good agreement with theoretical analysis. We have obtained stable single frequency operation, tuneable over 0.6 nm in the spectral range around 1064 nm. The laser operated with output power up to 110 mW at 53 nm. The total optical efficiency (808 nm to 532 nm) was 14%.     

Single longitudinal mode lasing of Tm,Ho:YAP microchip laser at 2000.4 nm

Single-longitudinal-mode operation of a b-cut Tm(5%), Ho(0.3%):YAlO₃ microchip laser is reported. An incident pump power of 1.85 W is used to generate the maximum single-frequency output power of 30 mW at 2000.4 nm, which represent a 1.6% optical-to-optical conversion efficiency. To the best of our knowledge, this is the first time to report on single-frequency operation in Tm,Ho:YAP lasers.     

A High-Power,Long-Wavelength Infrared ZnGeP<Subscript>2</Subscript> Opo Pumped by a <Emphasis Type="Italic">Q</Emphasis>-Switched Tm,Ho:GdVO<Subscript>4</Subscript> Laser

We report a high-power, long-wavelength infrared ZnGeP₂ (ZGP) optical parametric oscillator (OPO) pumped by a Q-switched Tm,Ho:GdVO₄ laser. The wavelength tuning range of 7.8–9.9 μm is realized by rotating the external angle of the ZGP crystal. We obtain an output power over 30 mW across the whole wavelength range and achieve a 1.71 W output power at 8.08 μm by transmitting the OPO parameters, corresponding to an idler laser slope efficiency of 12.1%.     

Comparison of RTP electro-optic Q-switch and acousto-optic Q-switch in Tm,Ho:GdVO<Subscript>4</Subscript> laser

We demonstrate a tunable, narrow linewidth, linearly polarized and gain-switched Cr²⁺:ZnSe laser pumped by a Tm, Ho:YVO₄ laser at 10 kHz pulse repetition frequency. By setting a quartz birefringent filter with a Brewster angle in the cavity, the linearly polarized Cr²⁺:ZnSe laser can be continuously tuned from 2.45 to 2.50 μm, and the output power was almost not changed. In addition, the linewidth was compressed to about 5 nm. At the incident pump power to the crystal of 14 W, the maximum output power of 2.84 W was obtained, corresponding to a slope efficiency of 20.4%.     

Improvement of diode-end-pumped 912 nm Nd:GdVO<Subscript>4</Subscript> laser performance based on microchannel heat sink

To solve the thermal dissipation problem in diode-end-pumped solid state lasers and improve the performance of 912 nm Nd:GdVO₄ lasers, a novel microchannel heat sink is designed and used in the experiments. Heat-transfer coefficients for the common heat sink and microchannel heat sink are calculated. The results obtained for the heat-transfer coefficient for the heat sink with a channel width of 0.2 mm is almost 5 times higher than that of the common one. The heat resistance for the novel heat sink is analyzed. Simulation results show that the maximum temperature in the laser crystal is reduced by 19°C at an absorbed pump power of 24.0 W, and the heat transfer ability significantly increases if the microchannel heat sink is used. Experimental results also indicate that the performance for a 912 nm laser is improved significantly using the novel heat sink, especially from the aspects of laser-beam quality and power scaling.     

Amplification of a <Emphasis Type="Italic">Q</Emphasis>-Switched Ho:GdVO<Subscript>4</Subscript> Oscillator in Thulium-Doped Large-Mode-Area Fiber

We report a high peak power, narrow linewidth, stable pulsed Ho:GdVO₄ amplifier based on thuliumdoped fiber, which produces 6.65 W average output power at 2,048 nm and 56.8 kW peak power with 11.7 ns pulse width at 10 kHz repetition rate. We use a simple Q-switched Ho:GdVO₄ laser as a seed laser and a thulium-doped fiber pumped by a 792 nm laser diode as an amplifier. The fiber amplifier provided 6.5 dB gain to the input signal. The spectral linewidth of the Ho:GdVO₄ amplifier remains < 0.5 nm with an M² beam quality of 1.36.     

Thermal focal length measurement of an LD-end-pumped Tm,Ho:GdVO4 laser

The thermal focal length of a Tm,Ho:GdVO₄ crystal was measured in this paper. The pump laser was 25.73 W, and the thermal focal length was 692.6 mm; based on the thermal focal length of a Tm,Ho:GdVO₄ crystal, a single end-pump continuous wave (CW) operation of Tm,Ho:GdVO₄ laser was designed to demonstrate the effect of thermal focal length, and a 0.26-W output power was high in considering the thermal focal length than in unconsidering the thermal focal length with a 26.1-W pump power.     

Lasing of diode-pumped c-cut Tm, Ho:YAlO3

We report on a diode-pumped Tm, Ho:YAlO₃ (c-cut) laser operating at 274 K. The maximum output power reaches 163 mW at an absorbed pump power of 2.3 W. A conversion efficiency from the absorbed pump power to laser output of 7.1% is demonstrated in Tm, Ho:YAlO₃, corresponding to a slope efficiency of 11.1%. The output center wavelength of Tm, Ho:YAlO₃ is 2102 nm with about a 2-nm FWHM. As far as we know, our work represents the first investigation of the laser performance of c-cut Tm, Ho:YAlO₃ at 274 K.