Versatile CMOS modulation-free self-isolating stabilized precision lasers on a chip
Ultra-low-noise stabilized lasers are a fundamental tool for precision quantum technologies, optical clocks, microwave and millimeter-wave generation, and fiber sensing. Existing systems rely on table-top bulk-optic components -- discrete lasers, reference cavities, isolators, modulators and frequency shifters -- limiting portability, scalability, and manufacturability. While these systems offer flexibility in laser design to tailor linewidth, frequency noise, and wavelength to specific applications, fully integrating a stabilized laser onto a chip without sacrificing performance and versatility has remained elusive. Here, we report integration of the precision stabilized laser in the low-loss silicon nitride photonic platform, combining a flexible isolator-free core laser design with a modulation-free stabilization cavity. We demonstrate a stabilized widely tunable self-isolating extended cavity tunable laser monolithically integrated with an on-chip coil-loaded Mach-Zehnder interferometer (CL-MZI). This design yields a fundamental linewidth of 1.7 - 10.5 Hz across a 60 nm tuning range, integral linewidth of 299 - 505 Hz over a 30 nm tuning range, frequency noise reduction of over 5 orders of magnitude, and an Allan-Deviation (ADEV) of 6.5x10-13 at 0.08 ms. We next highlight the versatility of this approach by demonstrating a self-isolating stimulated Brillouin scattering (SBS) laser, that provides nonlinear noise suppression of high frequency noise by multiple orders of magnitude, stabilized to an on-chip CL-MZI. The stabilized SBS laser achieves 4 Hz fundamental linewidth, 74 Hz integral linewidth, and ADEV of 2.8x10-13 at 5 ms. These results bring the performance and versatility of table-top stabilized laser systems to a chip for the first time, providing a path to scalable, low-cost, and manufacturable precision lasers for portable quantum, sensing, and communications applications.