High Repetition Rate Three-wavelength Laser for Particulate Organic Carbon Detection

A multi-wave laser source for POC hyperspectral detection LiDAR with high repetition rate and high beam quality was developed, using frequency stabilized seed source combined with fiber-bulk hybrid amplification technology and nonlinear frequency conversion technology. A 1064 nm single-frequency distributed feedback (DFB) semiconductor laser was used as the seeder, and an iodine molecular absorption pool was designed to control the frequency stability.

The seeder laser was chopped into nanosecond pulse train with a repetition rate of 5 kHz by an acousto-optic modulator after continuous fiber amplifier, and then amplified by a fiber-bulk hybrid cascaded amplifier. Finally, more than 2.6 mJ of 355 nm ultraviolet (UV) laser pulse energy was achieved by third harmonic generation through two LBO crystals, with conversion efficiency of about 42%. Pumped by 355 nm laser pulse, 486.1 nm blue laser pulse was obtained from an optical parametric oscillator system (OPO) based on BBO crystal, the maximum output pulse energy of 0.7 mJ was achieved with pulse width of 6.9 ns, corresponding to an optical-optical conversion efficiency of 26.9%.