Fast Lithium Niobate Photodetector

Abstract Despite various successes in lithium niobate (LN) integrated photonic devices (e.g., light sources, waveguides, modulators, etc.), LN photodetectors (PD) that converts light into electrical signals have received less research attention. Here, fast LN PDs are demonstrated. Defect energy states are used within the forbidden band of the LN as electron donor centers to generate free carriers in the conduction band under optical excitation in the visible range. Compared with previous pyroelectric LN PDs whose response speeds are normally limited to the order of 100 Hz, these LN PDs show faster responses up to 10 kHz. The dependences of the PDs' performances on the electrode gap, external driving voltage, illumination power, and impurity dopants are also studied. This work provides a step toward high‐performance LN PDs for constructing monolithic full‐functional integrated LN photonic chips.