Spectrally tailored and polarimetric shortwave infrared detection with narrowband response via quasi-BIC enhanced third harmonic generation

Abstract

Shortwave infrared (SWIR) detectors offer excellent penetration capabilities, making them highly valuable for applications such as target recognition and optical communication. However, traditional SWIR photodetectors suffer from high dark current, thermal noise, and the inability to resolve multidimensional information like polarization, making it challenging for highly sensitive and multidimensional sensing. Herein, we proposed a “symmetry breaking” principle to theoretically design an upconversion SWIR detector based on a silicon (Si) metasurface, which enables two-dimensional detection of light intensity and polarization information with high resolution and spectral tunability. By exciting a quasi-bound state in the continuum (quasi-BIC) mode with broken symmetry, this metasurface can achieve efficient third harmonic generation with an efficiency of 0.02%, which is seven orders of magnitude higher than that of the planar Si membrane. The efficient upconversion process increases the theoretical detectivity up to 7.9 × 1012 Jones in the SWIR band (1535.6 nm), comparable to that of commercially available InGaAs detectors. Benefiting from the filtering characteristics of the metasurface, the detector exhibits a response bandwidth of only 0.2 nm, making it one of the highest performance narrowband photodetectors in this spectral range. Furthermore, compared with conventional photodetectors, which only capture one-dimensional light intensity information, the third harmonic signal exhibits strong polarization sensitivity, which enables us to design a dual-dimensional optical communication system that doubles the data rate without additional readout time. This work provides a new technological pathway for the design of multiplexed high precision optical communication detectors.