Blue to Near-IR Integrated PZT Silicon Nitride Modulators for Quantum and Atomic Applications
Modulation and control of lasers and optical signals is necessary for trapped-ion and cold neutral atom quantum systems. Given the diversity of atomic species, experimental modalities, and architectures, integrated optical modulators designed to operate across the visible to near-infrared spectrum are a key step towards portable, robust, and compact quantum computers, clocks, and sensors. Integrated optical modulators that are wavelength-independent, CMOS-compatible, and capable of maintaining low waveguide losses and a high resonator quality factor, DC-coupled broadband frequency response, and low power consumption, are essential for scalable photonic integration. Yet progress towards these goals has remained limited. Here we demonstrate four types of integrated stress-optic lead zirconate titanate (PZT) silicon nitride modulators: a coil Mach-Zehnder modulator, a coil pure phase modulator, and bus-coupled and add-drop ring resonator modulators, with operation from 493 nm to 780 nm. The coil MZM operates at 532 nm with a V$π$ of 2.8V, a 0.4 MHz 3-dB bandwidth, and an extinction ratio of 21.5dB. The coil phase modulator operates at 493 nm with a V$π$ of 2.8V and low residual amplitude modulation of -34 dB at a 1kHz offset. The bus-coupled ring resonator modulator operates at 493 nm and the add-drop ring resonator modulator operates at 780 nm. The ring-based modulators have an intrinsic quality factor of 3.4 million and 1.9 million, a linear tuning strength of 0.9 GHz/V and 1 GHz/V, and a 3-dB bandwidth of 2.6 MHz and 10 MHz, respectively. All four modulator designs maintain the low optical waveguide loss of SiN, are DC coupled with broadband frequency response, operate independent of wavelength, and consume only tens of nW per actuator. Such solutions unlock the potential for further integration with other precision SiN components to realize chip-scale atomic and quantum systems.