2.05-µm all-fiber laser source designed for CO₂and wind coherent lidar measurement

Abstract

This work reports on an all-fiber pulsed laser source for simultaneous remote sensing of <i>C</i><i>O</i>₂ concentration and wind velocity in the 2.05 µm region. The source is based on a polarization-maintaining master oscillator power amplifier (MOPA) architecture. Two narrow-linewidth master oscillators for ON-line/OFF-line <i>C</i><i>O</i>₂ differential absorption lidar operation alternately seed a four-stage amplifier chain at a fast switching rate up to 20 kHz. The MOPA architecture delivers laser pulses of 120 µJ energy, 200 ns duration (600 W peak power) at 20 kHz pulse repetition rate (2.4 W average power). The output linewidth is lower than 5 MHz, close to the pulse Fourier transform limit, and the beam quality factor is <i>M</i>²=1.12. The source also provides a pre-amplified 20 mW local oscillator with a relative intensity noise of -160<i>d</i><i>B</i>/<i>H</i><i>z</i> that ensures optimal performance for future coherent detection.