A monolithically integrated tunable single longitudinal mode extended cavity ring laser using Intracavity Mach-Zehnder interferometers

A ring geometry laser with a wavelength tunable intracavity filter is demonstrated. The device is realized as a photonic integrated circuit and fabricated within COBRA InP active-passive multi project wafer run. The device under test features a three stage asymmetric Mach-Zehnder interferometer filtering scheme allowing for a single mode operation with the side mode suppression and contrast ratios of 43 dB and 60 dB respectively when the laser is DC biased at 2.5 times of the threshold current.