Abstract

Frequency discriminators are attractive devices for reducing integrated laser linewidths for coherent communication systems and high purity microwave photonic systems. Standard diode lasers have MHz level linewidths, with recent integrated delay line lasers showing a 50 kHz [1]. Typical on chip devices allow for a few cm of delay in a Mach Zehnder (MZI) configuration, but larger delays are needed for integrated devices. Here, we show a fully integrated Si₃N₄ ring resonator used as an optical discriminator with a sensitivity better than a 10 meter delay line interferometer. We utilize the Pound-Drever-Hall (PDH) technique to characterize the resonator bandwidth and improve the linewidth of a state of the art commercial laser by locking to the waveguide coupled resonator.

© 2015 Japan Society of Applied Physics, Optical Society of America