Dual-Wavelength $\phi$-OFDR Using a Hybrid-Integrated Laser Stabilized to an Integrated SiN Coil Resonator

We demonstrate dual-wavelength distributed acoustic sensing over 37 km of standard single-mode fiber using $\phi$-OFDR, utilizing a scalable hybrid-integrated dual-wavelength laser chip frequency-locked to a high-Q integrated SiN coil resonator.