Power spectrum of frequency noise of semiconductor lasers with optical feedback from a high-finesse resonator

The power spectrum of frequency noise of a semiconductor laser with optical feedback from a high-finesse resonator is calculated using a differential-difference equation. The results are compared with measurements. The feedback reduces the frequency noise at low Fourier frequencies, while enhancing the oscillations near the relaxation oscillation frequency, eventually driving the system unstable. The results show a simple way to choose the parameters of the high-finesse cavity to minimize the frequency noise without causing instabilities.