Narrow-line, low-amplitude noise semiconductor laser oscillator in the 780 nm range

We present a narrow-band and low-intensity noise laser oscillator around 780 nm built from a commercially available laser diode. We have stabilized the frequency of two extended cavity diode lasers on the same high finesse Fabry–Pérot cavity using a wide-band electronic feedback loop. We have reduced the relative linewidth of the two lasers down to 570 Hz and strongly concentrated their energy: 95% in a relative bandwidth smaller than 10 kHz. The intensity noise of this device corresponds to the shot noise for Fourier frequencies larger than a few megaHertz.