Er:YAG Methane Lidar Laser Technology

We report on the design, fabrication and testing of a 1645 nm injection-seeded and locked Er:YAG laser resonator with single-frequency output operating at a methane line with > 500 μJ/pulse at 4-7 kHz pulse repetition frequencies with a pulse width < 1 μsec. The state-of-the-art technology for lidar methane sensing uses Optical Parametric Oscillator (OPO)/Optical Parametric Amplifier (OPA)–based systems. A key innovation of our system is the use of resonantly 1532 nm pumped Er:YAG gain crystals, which results in improved efficiency and a reduced footprint compared with the current OPO systems. Another feature adapted in our system is the high bandwidth injection locking technique which includes fast piezoelectric mirror and in-house developed FPGA locking algorithm, capable of active locking and wavelength control for each pulse as pulse repetition frequencies up to 10 kHz. The single frequency laser output follows the seed diode wavelength and which scans across the targeted methane absorption line.