Fiber-based coherent DIAL / Doppler Lidar at 1645 nm for remote sensing of methane plumes

A new coherent, fiber-based, and dual-function DIAL/Doppler Lidar is currently being developed at Onera, for remote sensing of CH4 plume in case of industrial onshore or offshore gas leaks. The system is designed for operation at 1645 nm in pulsed mode to allow for range-resolved measurements. It relies upon a new fiber laser source developed in the lab. The laser is a semiconductor laser diode amplified and pulsed through a MOFPA architecture using two Raman amplification stages. The lidar emits 10 μJ, 100 ns, linearly polarized pulses at 20 kHz repetition rate from a monomode fiber. The pulse spectral width is 10 MHz, close from the Fourier limit, and is suitable for coherent detection. The frequency stability of emitted pulses is below 100 kHz (<0.1 m/s) for time accumulation over 20 ms. The lidar has been set in monostatic configuration for wind and CH4 measurements tests.