Frequency noise reduction of a diode laser by using the FM sideband technique

The frequency of a 1.5-microm three-electrode multiple-quantum-well distributed-feedback diode laser was stabilized to a reference Fabry-Perot cavity by using a current-modulated FM sideband technique. The low-frequency AM noise imposed on the frequency error signal was effectively reduced with this technique, and the power spectrum density of the FM noise was reduced to less than 25 Hz(2) /Hz at a Fourier frequency of less than 10 kHz, which corresponded to a Lorentz spectral half-linewidth of approximately 80 Hz.