Broadband Transient Spectral Band Detection and Computation Based on 2D-vdW Nano Device.

The ability to resolve optical signals with different wavelengths or colors is essential for a wide range of advanced photonic applications, such as wavelength-division multiplexed multichannel optical communications and multiparameter intelligent sensing systems. However, most of the current solutions rely on several different detectors to form a complex detection system. Herein, we exploit intrinsic transient characteristics of 2D semiconductor devices for broadband spectral band recognition in only one detector. We find that four key transient modes, including positive/negative step response, overshoot, and hysteresis, show distinct spectral band-dependent characteristics, which makes multi-band spectral discrimination possible. We verify this through three different measurement systems. We call this method Photocurrent Transient Response Spectral Band Recognition (PTRSBR). Using a single MoS2/WSe2/MoS2 2D van der Waals bipolar junction transistor (2D-vdW BJT), we obtain measurement results from four spectral bands of wavelengths in the broad range of 500 nm-0.3 mm, under a bias voltage of as low as 1 V without scanning. Moreover, the underlying physical mechanisms are proposed with mathematical models for these modes. Furthermore, a transient spectral band detection and computation hardware system prototype is demonstrated. It lays the foundation for compact detectors suitable for use in optical communication and spectral imaging.