Waveguide‐Integrated Gate‐Controlled Reconfigurable Phototransistor Based on a WSe ₂ /MoS ₂ Heterojunction on Thin‐Film Lithium Niobate

The development of multifunctional photonic devices with ultra‐compact footprints and excellent optoelectronic performance based on thin‐film lithium niobate (TFLN) has become an important research focus in the field of photonic integration. In this study, we demonstrate a reconfigurable field‐effect transistor (RFET) based on a WSe 2 /MoS 2 van der Waals heterostructure integrated onto a TFLN waveguide. This single RFET device integrates logical rectification and high‐performance photodetection functionalities. Through back‐gate voltage modulation, the RFET realizes polarity transition and achieves precise switching between forward and reverse rectification behaviors, thereby enabling the function of a gate‐controlled bidirectional half‐wave logic rectifier. Furthermore, the RFET exhibits a broadband photoresponse covering the wavelength range from 635 to 1550 nm. Under zero gate voltage and a bias voltage of −1 V, the device shows an ultralow dark current as low as 269 pA. Under biased operation, the responsivity reaches 2245 A/W, while in the self‐powered mode it remains at 144 mA/W. Notably, both responsivity values rank among the highest reported for waveguide‐integrated devices to date. These results highlight the strong potential of RFET‐based multifunctional devices for advancing next‐generation photonic integrated chips and reconfigurable logic devices.