Waveguide integrated high-speed black phosphorus photodetector on a thin film lithium niobate platform

Abstract

The thin film lithium niobate platform has shown its potential to support high-performance active and passive integrated photonic devices. Yet, due to the transparency of lithium niobate, it is not suitable for building a photodetector monolithically for conventional communication wavelengths. In this work, we demonstrate a high-speed photodetector on the thin film lithium niobate platform using hybrid integration of two-dimensional materials, i.e., black phosphorus. The black phosphorus and lithium niobate hybrid waveguide exhibit a high absorption coefficient of 1.56 dB/µm. The constructed metal-semiconductor-metal photodetector also presents a high responsivity of 2.64 A/W (at an input optical power of 25.1 µW). The 3-dB bandwidth of the device is as high as 1.97 GHz.