In this paper, a practical single-frequency high-repetition linearly-polarized eye-safe all-fiber laser with constant peak power is demonstrated. It is based on master-oscillator power amplifier (MOPA) system. A distributed feedback laser diode simulating at 1550nm with narrow linewidth of 2.3 kHz is employed as the seed source. It is modulated to a pulse laser with high repetition of 20 kHz and peak power of 10mW by an acousto-optic modulator (AOM). The pulse width is tunable between 100ns to 400ns. Two-stage cascade amplifier is established, which consists of a pre-amplifier and a power-amplifier. Amplified spontaneous emission (ASE) and stimulated billion scattering are well suppressed by special management. The output peak power of 30W is obtained, which has nearly diffraction-limited beam quality. It operates in linewidth of 1.2MHz, polarization-extinction ratio (PER) of 25dB and signal-to-noise ratio (SNR) of more than 40dB. Gain of the whole amplifier achieves nearly 35dB. Furthermore, an embedded control system (ECS) based on the WinCE operating system (OS) and the chip of S3C2440 is proposed. This control system based on closed-loop feedback technology makes the peak power keeping constant even the pulse width tunable, which is convenient for the end user of the radar. This robust portable laser is remarkable and fulfills the desire of coherent detection excellently.
In the paper, we reported a single-frequency(SF), single-mode(SM), linear-polarized ytterbium-doped all-fiber master
oscillator power amplifier (MOPA) system consisting of two stage amplifier which could be used in coherent detection.
With a pump power of 17.5W at 976nm, the system emitted up to 12.7 W of single-frequency radiation at a wavelength
of 1064 nm with the polarization-extinction ratio (PER) more than 35dB and signal-to-noise ratio (SNR) more than 40dB.
The final-stage amplifier operated with a high conversion efficiency of 73% and the gain of the whole amplifier achieved
31 dB, it has nearly diffraction-limited beam quality.