Fengdong Chen

Diode pumped operation of tm, Ho:YAP microchip laser

Single-wave length operation of a c-cut Tm (5%), Ho (0.3%):YAP microchip laser pumped by a fiber-coup led diode-laser was reported. Under cryogenic temperature, the output power of 188 mW was obtained under the incident power of 2230 mW, corresponding to the slope efficiency was 12.2%. As much as 168 mW output and slope efficiency of 5.7% was obtained under the pump power of 3400 mW at 291 K. In addition, a maximum single-wave length output power of 60 mW at wavelength of 2130.2 nm and 14 mW at wavelength of 2102.4 nm is demonstrated under 77 and 291 K, respectively.

Room temperature single-frequency output from a diode-pumped Tm,Ho:YAP laser

Single-frequency operation in the range of 2102.45-2102.54 nm and 2130.72-2130.82 nm is demonstrated from a Tm,Ho:YAP laser at room temperature. To our knowledge, this is the first time a room temperature single-frequency Tm,Ho:YAP laser of up to 72.6 mW at 2102.5 nm with Fabry-Perot etalons has been obtained. Regulating the elevation angle of the two etalons, 42.0 mW at 2130.8 nm was obtained. The single-longitudinal-mode laser can be used as a seed laser for coherent wind measurements and differential absorption lidar systems.

Diode-pumped single-frequency Tm:YAG laser with double etalons

A diode end-pumped single-frequency Tm:YAG laser at room temperature is reported. The maximal output power of single-frequency is as high as 60 mW by using two uncoated fused YAG etalons, which are respectively 0.1 and 1.0 mm thick. We obtained a single frequency Tm:YAG laser at 2013.91 nm. The change of the lasing wavelength on temperature was also measured. The single-longitudinal-mode laser can be used as a seed laser for coherent wind measurements and differential absorption LIDAR systems.

Diode-pumped Q-switched Tm:LuAG ring laser operation at room temperature

Abstract2-μm lasers with high pulse energy and long pulse width of hundreds of nanoseconds are needed urgently in the accurate wind velocity lidar systems. This paper presented the acoustic-optical Q-switched Tm:LuAG laser performance in a pulsed-laser-diode end-pumping figure-eight ring resonator structure. Pulse energy and pulse width are investigated with the increasing of the incident pump energy at different repetition rate operation. Maximum energy of 3.3 mJ with the pulse width of 199 ns and 1.8 mJ with pulse width of 293 ns are obtained at the repetition rate of 20 and 50 Hz, respectively. Under Q-switched operation, the peak output wavelength is 2.022 μm at all time, and the beam quality factors are lower than 2 times diffraction-limited measured by a knife-edge traveling method.

Comparison of electro-optical and acousto-optical Q-switched, high repetition rate Nd:GdVO4 laser

The differences between the performances of electro-optical (EO) and acousto-optical (AO) Q-switched, diode pumped Nd:GdVO4 laser at high repetition rates were detailed in this paper. The results revealed that EO Q-switch was more favorable to obtain short pulse width and high peak power laser than AO Q-switch under high repetition rate operation. The minimum pulse widths at 100 kHz were 20.2 ns under EO operation and 28.7 ns under AO operation, corresponding to peak powers of 3.1 kW and 2.2 kW, respectively. The corresponding values at 10 kHz were 5.3 ns, 9.0 ns and 77.4 kW, 45.6 kW, respectively.

Diode-end-pumped Tm, Ho:YVO4 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 M2 factor was measured to be 1.4.

A comparative study on diode-pumped continuous wave Tm:Ho:YVO4 and Tm:Ho:GdVO4 lasers

In this paper, we presented experimental results concerning on the laser characteristics of two microchip lasers emitting in the 2 μm range, Tm:Ho:YVO4 microchip laser and Tm:Ho:GdVO4 microchip laser. At a heat sink temperature of 283 K, the maximum output power of Tm:Ho:YVO4 laser and Tm:Ho:GdVO4 laser is 47 and 34 mW under absorbed pump power of 912 mW, respectively. High efficiency can be achieved for both lasers at room temperature. Nevertheless, compared with Tm:Ho:GdVO4 laser, Tm:Ho:YVO4 laser can operate on single frequency with high power easily. At the heat sink temperature of 288 K, as much as 16.5 mW of 2052.3 nm single-longitudinal-mode (SLM) laser was achieved for Tm:Ho:YVO4 laser. Under the same condition, only 8 mW of 2048.5 nm SLM laser was achieved for Tm:Ho:GdVO4 laser.

LD-end-pumped 60 pm linewidth Tm:YLF laser

Narrow linewidth continuous-wave Tm:YLF laser at room temperature with a Volume Bragg grating and double Fabry-Perot etalons by using the end-pumping configuration was presented. The Tm:YLF laser operates at 1907.3 nm with FWHM of approximately 60 pm. We achieved the maximum output power of 1.92 W when the incident pump power of 13.9 W, corresponding to the optical-to-optical conversion efficiency of 13.8% and slope efficiency of 16.4%.

Room temperature diode-pumped Tm,Ho:YAP laser with double etalons

A diode end-pumped single-frequency Tm,Ho:YAP laser at room temperature was reported. We obtain a single frequency Tm,Ho:YAP laser of up to 31 mW with Fabry-Perot etalons in the cavity at 2130.8 nm. The optical conversion efficiency is 1.0% and the slope efficiency is 6.3%. The measured full width at half maximum (FWHM) is approximately 65 pm. The single-longitudinal-mode (SLM) laser can be used as a seed laser for coherent wind measurements and differential absorption LIDAR systems.

Absolute distance measurement system with micron-grade measurement uncertainty and 24 m range using frequency scanning interferometry with compensation of environmental vibration.

We establish a theoretical model of the Doppler effect in absolute distance measurements using frequency scanning interferometry (FSI) and propose a novel FSI absolute distance measurement system. This system incorporates a basic FSI system and a laser Doppler velocimeter (LDV). The LDV results are used to correct for the Doppler effect in the absolute distance measurement signal obtained by the basic FSI system. In the measurement of a target located at 16 m, a measurement resolution of 65.5 μm is obtained, which is close to the theoretical resolution, and a standard deviation of 3.15 μm is obtained. The theoretical measurement uncertainty is 8.6 μm + 0.16 μm/m Rm (k = 2) within a distance range of 1 m to 24 m neglecting the influence of air refractive index, which has been verified with experiments.