SummaryAn automatic linewidth control loop which provides stable optimum linewidth reduction and single cavity mode operation of an external cavity semiconductor laser is presented. Stable linewidth reduction from 70 MHz to below 2 MHz is obtained for a 1.3 μm BH-laser, whereas simultaneous mean frequency stabilization to within 1 kHz and linewidth reduction from 17 MHz to 1.6 MHz is demonstrated for an 830 nm CSP-laser.
A novel frequency stabilization method for the seed laser of the pulse optical parametric oscillator in differential absorption lidar