Ultra-Low-Power Tuning in Hybrid Barium Titanate–Silicon Nitride Electro-optic Devices on Silicon

As the optical analogue to integrated electronics, integrated photonics has\nalready found widespread use in data centers in the form of optical\ninterconnects. As global network traffic continues its rapid expansion, the\npower consumption of such circuits becomes a critical consideration.\nElectrically tunable devices in photonic integrated circuits contribute\nsignificantly to the total power budget, as they traditionally rely on\ninherently power-consuming phenomena such as the plasma dispersion effect or\nthe thermo-optic effect for operation. Here, we demonstrate ultra-low-power\nrefractive index tuning in a hybrid barium titanate (BTO)-silicon nitride (SiN)\nplatform integrated on silicon. We achieve tuning by exploiting the large\nelectric field-driven Pockels effect in ferroelectric BTO thin films of sub-100\nnm thickness. The extrapolated power consumption for tuning a free spectral\nrange (FSR) in racetrack resonator devices is only 106 nW/FSR, several orders\nof magnitude less than many previous reports. We demonstrate the technological\npotential of our hybrid BTO-SiN technology by compensating thermally induced\nrefractive index variations over a temperature range of 20 {\\deg}C and by using\nour platform to fabricate tunable multiresonator optical filters. Our hybrid\nBTO-SiN technology significantly advances the field of ultra-low-power\nintegrated photonic devices and allows for the realization of next-generation\nefficient photonic circuits for use in a variety of fields, including\ncommunications, sensing, and computing.\n