Chip-scale mid-infrared digitalized computational spectrometer powered by silicon photonics MEMS technology

Miniaturized spectrometers are attracting widespread interest due to the rising demand for portable spectroscopic applications. While the chip-scale spectrometers are widely investigated using silicon photonics technology, few research have addressed the need for a mid-infrared (MIR) integrated chip-scale spectrometer due to the lack of an effective reconfigurable photonics approach. In this paper, we present a novel solution using silicon photonics MEMS technology in the MIR region (3.6–5 µm wavelength range). We adopt a computational spectrometry scheme using the digitalized control of cascaded MEMS-tunable waveguide couplers. The MEMS waveguide couplers are operated in digital on/off mode, thus making the device immune to driving voltage fluctuations and robust for on-chip field sensing applications. Moreover, a comprehensive numerical analysis method is discussed to systematically evaluate the performance of the computational spectrometer, including its resolution and operational bandwidth. As a proof-of-concept, a chip-scale spectrometer realized by seven cascaded MEMS-actuated waveguide coupler is demonstrated. The sparse spectral reconstruction is demonstrated in the wavelength range from 3.65 to 4.1 µm and the dual-peaks reconstruction results indicate a resolution of 8 nm. Besides, response time and power consumption of the proposed device are experimentally characterized. Benefitting from good scalability, the spectral resolution can be further improved by increasing the number of waveguide coupler stages. The proposed work has the potential to realize lab-on-a-chip applications with advances in MIR silicon photonics. © 2001 Elsevier Science. All rights reserved.