Blue to near-IR integrated PZT silicon nitride modulators for quantum and atomic applications

Modulation and control of lasers and optical signals are necessary for trapped-ion and cold neutral atom quantum systems. Given the diversity of atomic species, experimental modalities, and architectures, integrated optical modulators that are designed to operate across the visible to near-infrared (NIR) 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 (Q), DC-coupled broadband frequency response, and low power consumption are essential for scalable photonic integration. Yet progress towards these goals has remained limited. To show the versatility of this platform, we demonstrate four types of integrated stress-optic lead zirconate titanate (PZT) silicon nitride (Si₃N₄) modulators - a coil Mach-Zehnder modulator (coil MZM), a coil pure phase modulator, and bus-coupled and add-drop ring resonator modulators, with operation from 493 nm to 780 nm. The PZT-actuated coil MZM operates at 532 nm with a Vπ of 2.8 V, a DC - 0.4 MHz 3-dB bandwidth, and an extinction ratio of 21.5 dB. The PZT-actuated nitride coil phase modulator operates at 493 nm with a Vπ of 2.8 V and low residual amplitude modulation (RAM) of -34 dB at a 10 kHz 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 (Q_i) of 3.4 million and 1.9 million, a linear tuning strength of 0.92 GHz/V and 1.01 GHz/V, and a 3-dB bandwidth of DC - 2.6 MHz and DC - 10 MHz, respectively. All four modulator designs maintain the native low optical waveguide loss of SiN, are DC coupled with broadband frequency response, operate independently of wavelength, and consume only tens of nW per actuator. Such solutions unlock the potential for further integration with other precision silicon nitride components to realize chip-scale atomic and quantum systems.