Theoretical analysis and simulation of a high SNR and real-time MPMG-based computational spectrometer

Achieving a balance between signal-to-noise ratio (SNR) and real-time performance in infrared (IR) spectral detection of weak and moving targets is a significant challenge. Here, we propose a long-wave infrared (LWIR) computational spectrometer (MPMGFTS) based on a multi-depth phase modulation grating (MPMG). MPMG functions as the core component of the MPMGFTS. To ensure accuracy in calculating the diffraction field of MPMG, Rigorous Coupled-Wave Analysis (RCWA) theory is employed to build the field distribution model. Additionally, the effects of structural duty cycle, incident angle, and fabrication errors are analyzed. MPMGFTS offers both high SNR and temporal resolution. It retains the transient response characteristics of grating-based spectrometers (GS) while improving the SNR by approximately 120 times compared to GS. Our study on MPMGFTS offers a novel and effective approach for remote sensing and target recognition.