Sub-kHz single-frequency pulsed semiconductor laser based on NPRO injection locking

We report a single-frequency, narrow-linewidth semiconductor pulsed laser based on pump current modulation and an optical injection locking technique.A homemade monolithic non-planar ring oscillator laser is employed as the seed to guarantee the single-frequency narrow-linewidth performance.Simultaneously, pulse operation is achieved by directly modulating the pump current of the semiconductor laser.The single-frequency pulsed laser has achieved a pulse repetition rate of 50 kHz-1 MHz, a pulse duration ranging from 120 ns to a quasi-continuous state, and a peak power of 160 mW.Moreover, the single-frequency pulsed laser (SFPL) has reached a carrier linewidth as narrow as 905 Hz 16 Hz, and an optical spectrum signal-to-noise ratio of better than 70 dB at a center wavelength of 1064.45 nm.Such an extremely narrow-linewidth, repetition-rate, and pulse-width tunable SFPL has great potential for applications in coherent LIDAR, metrology, remote sensing, and nonlinear frequency conversion.