Linquan Niu

Single- and dual-pulse oscillation in a passively Q-switched Nd:YAG microchip laser

Experimental investigation of single and dual pulses in a passively Q-switched Nd:YAG microchip laser with a Cr4+:YAG saturable absorber has been reported. The dual pulses consist of a main and a satellite pulse with respective spectra, intensities, and durations. It is found that the preponderant oscillating mode gives birth to the main pulse, and the other oscillating mode corresponds to the satellite pulse. Our results demonstrate that the dual-pulse emission results from double-longitudinal-mode oscillation in high pump regime.

A sub-nanosecond narrow-linewidth pulsed laser source with controllable repetition rate

A compact all-fiber sub-nanosecond narrow-linewidth Yb-doped fiber amplifier with a controllable repetition rate has been investigated. Tunable temporal pulses ranging from sub-nanoseconds to 10 ns with repetition rates from 10 kHz to 1 MHz are obtained by controlling the waveform of the injected electrical-pulse signal. Due to the practical requirements of our intended applications, a distributed feedback semiconductor laser with a wavelength of 1064 nm, pulse duration of 802 ps, repetition rate of 500 kHz and average power of 20 μW is used to seed a dual-stage single mode Yb-doped fiber amplifier. The characteristics of the amplified pulses are measured and exhibit a temporal duration of 810 ps with an average power of 31.2 mW. The gain of the amplified pulse is about 32 dB at the maximum output power. A notable feature of the amplifier pulses is that the spectral linewidth can be maintained to less than 0.1 nm during the dual-stage amplifier process. The noise level lies more than 22 dB below the peak value of the amplified spectrum, which represents an excellent signal-to-noise ratio.

The pulsed all fiber laser application in the high-resolution 3D imaging LIDAR system

An all fiber laser with master-oscillator-power-amplifier (MOPA) configuration at 1064nm/1550nm for the high-resolution three-dimensional (3D) imaging light detection and ranging (LIDAR) system was reported. The pulsewidth and the repetition frequency could be arbitrarily tuned 1ns~10ns and 10KHz~1MHz, and the peak power exceeded 100kW could be obtained with the laser. Using this all fiber laser in the high-resolution 3D imaging LIDAR system, the image resolution of 1024x1024 and the distance precision of ±1.5 cm was obtained at the imaging distance of 1km.