Ultra-broadband tunable miniaturized spectroscopy based on epsilon-near-zero effect enabled electro-optic modulation

Miniature spectrometers hold significant potential in point-of-care diagnosis, on-site inspection and portable optical sensing. However, large photodetector arrays increase the complexity and cost of miniature spectrometers, particularly in the infrared band. A single photodetector integrated with a reconfigurable spectral response offers a promising approach to solve this issue, but the wavelength tuning range of spectral response cells remains limited. In this paper, a concept of non-resonant electro-optic modulation enabled ultra-broadband miniaturized spectroscopy is proposed, where the spectral tuning range of 3000 nm and the spectral resolution of 6 nm at 2.29 μm are predicted in simulation. Light modulation is realized with a 45° groove micro-mirror consisting of a silicon /dielectric /TCOs/metal stack, where the large refractive index contrast between Si/metal and ENZ material facilitates strong ENZ mode confinement. Without an integration of any resonator, the peak wavelength depends solely on the electron concentration within the ENZ layer, resulting in such a broad operating band from near-infrared to mid-infrared. This technique shows promising potential as a low-cost platform for on-site inspection.