Pound-Drever-Hall locking of 780 nm laser using on-chip Mach-Zehnder interferometer

Low-noise, narrow-linewidth lasers are of great importance for applications demanding exceptional spectral purity, for example the laser cooling. While the cold atom systems usually use large, expensive, sophisticated lasers to achieve certain wavelengths, photonic integrated circuits can enable portable laser frequency locking systems. This work presents an integrated 780 nm laser stabilization scheme using an on-chip silicon nitride Mach-Zehnder interferometer as a reference. Through the Pound-Drever-Hall locking technique, the system reduces frequency noise by 48.5 dB and narrows the integral linewidth to 15.4 kHz. This demonstrates a compact, high-performance solution for laser stabilization, showing the potential for rubidium atom cooling and quantum manipulation.