UC Santa Barbara

Modulation-based control and locking of lasers, filters, and other photonic components is a ubiquitous function across many applications that span the visible to infrared (IR) range, including atomic, molecular, and optical (AMO), quantum sciences, fiber communications, metrology, and microwave photonics. Today, modulators used to realize these control functions consist of high-power bulk-optic components for tuning, sideband modulation, and phase and frequency shifting while providing low optical insertion loss and moderate operation bandwidth. To enhance the power efficiency, scalability, and cost-effectiveness of these applications while reducing their size and weight, it is imperative to implement modulation control functions in a low-loss, wafer-scale complementary metal-oxide-semiconductor (CMOS)-compatible photonic integration platform. The silicon nitride integration platform has been successful in realizing extremely low waveguide losses across the visible to infrared range [1,2] and components including high-performance lasers [3], filters [4], resonators, stabilization cavities [5], and optical frequency combs [6]. However, the advancement in incorporating low-loss, low-power modulators into the silicon nitride platform while maintaining compatibility with wafer-scale processes has been constrained.This dissertation represents significant progress in the integration of a piezo-electric (PZT, lead zirconate titanate) actuated micro-ring modulator within a fully planar, wafer-scale silicon nitride platform, at both 1550 nm and 780 nm. This integration maintains low optical losses at infrared and visible wavelengths, accompanied by an order of magnitude increase in optical bandwidth (DC to 25 MHz 3-dB) and an order of magnitude lower power consumption of 20 nW improvement over prior PZT modulators [7,8]. This work demonstrated control applications utilizing the developed PZT modulator as sideband modulation in a Pound-Drever Hall (PDH) lock loop for laser stabilization and as a laser carrier tracking filter. Subsequently, an AOM/EOM-free laser stabilization scheme is demonstrated unifying both functions using a single PZT modulator. This approach has the potential to pave the way for photonic integrated stabilized lasers, given the compatibility of the PZT modulator with both the integrated reference cavity [9] and lasers [3,10]. The PZT modulator design can be extended to the visible region in the ultra-low loss silicon nitride platform with waveguide design changes. The integration of PZT modulation in the ultra-low loss silicon nitride waveguide platform enables modulator control functions in a wide range of visible to IR applications such as atomic and molecular transition locking for cooling, trapping and probing, controllable optical frequency combs, low-power external cavity tunable lasers, quantum computers, sensors and communications, atomic clocks, and tunable ultra-low linewidth lasers, and ultra-low phase noise microwave synthesizers. Finally, more complex photonic structures with PZT control are investigated, such as symmetrically coupled photonic molecules and their potential applications in optical isolators and high-order switchable filters. These results open the door to novel device designs and a wide range of applications including tunable lasers, high-order suppression ultra-narrow linewidth lasers, dispersion engineering, optical parametric oscillators, physics simulations, and atomic and quantum photonics.