Ultralow noise and supermode suppression for high-speed photonic sampling with a semiconductor diode ring laser

Summary form only given. We report the most extensive supermode suppression (and lowest pulse-train noise) achieved to date with a 10 GHz external-cavity semiconductor diode ring laser. Using a recently developed wideband modification of an established homodyne noise measurement technique, we present high dynamic range measurements out to Nyquist offsets which show strong supermode suppression to levels below -140 dBc/Hz. In the loss-modulated laser geometry, the free-space section contains extensive isolation and polarization-controlling optics surrounding an InGaAsP SOA. For supermode suppression, a high-finesse (/spl sim/180) fiber-Fabry-Perot (FFP) filter (FSR = 10 GHz) and 3-ring polarization controller (PC) are inserted before the Mach-Zehnder modulator (MZM).