>20 dB phase noise reduction by locking an off-the-shelf external cavity laser having sub-kHz linewidth to an on-chip wavelength reference in Si3N4 using an electronic feedback loop on the diode injection current

Abstract

Wavelength stabilization of external cavity lasers is a of key importance to exploit their sub-kHz intrinsic linewidth. In this work we demonstrate > 20 dB optical phase noise reduction at acoustic frequencies using a simple off-the-shelf electronic feedback loop. The novelty here is that we exploit an on-chip optical frequency discriminator (OFD) in Si3N4 (TriPleX), based on an aMZI with a path length difference of 1.4 m, having less than 10 dB loss. The used setup has a bandwidth of approximately 1 MHz, allowing for wavelength modulation depth in the order of tens of MHz.