All-fiber multifunction continuous-wave coherent laser radar at 155 µm for range, speed, vibration, and wind measurements

Abstract

The design and performance of a simple, multifunction 1.55-µm continuous-wave (cw) and frequency-modulated cw coherent laser radar system with an output power of 1 W is presented. The system is based on a semiconductor laser source plus an erbium-doped fiber amplifier, a polarization-independent fiber-optic circulator used as the transmit–receive switch, and digital signal processing. The system is shown to be able to perform wind-speed measurements even in clear atmospheric conditions when the visibility exceeds 40 km. The aerosol measurements indicate the potential to use single-particle detection for wind measurements with enhanced sensitivity. The system can perform range and line-of-sight velocity measurements of hard targets at ranges of the order of several kilometers with a range accuracy of a few meters and a velocity accuracy of 0.1 m/s by use of triangular-wave frequency modulation with compensation of the frequency-modulation response of the semiconductor laser. The system also demonstrates a capability for vibration sensing.