Millimeter-wave signal generation by optical heterodyne of two channels from an arrayed waveguide grating-based multi-wavelength laser

Arrayed waveguide grating multi-wavelength lasers have been shown to provide simultaneously multiple wavelengths. In this work we report the characteristics of the heterodyne signal in the millimeter-wave range. The optical linewidth measured from the modes generated by the different channels can be as narrow as 120 kHz. We present for the first time the beat note obtained from mixing two channels onto a high speed photodiode, demonstrating a narrow linewidth of 250 kHz, which is to the best of out knowledge the narrowest beat-note measured from a free running monolithic semiconductor dual wavelength source working on the 1,550 nm wavelength range.