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

Area of Science:

• Optics and Photonics
• Spectroscopy
• Materials Science

Background:

• Miniature spectrometers are crucial for portable sensing but face challenges with photodetector complexity and cost, especially in the infrared spectrum.
• Existing reconfigurable spectral response methods have limited wavelength tuning ranges, hindering broad applicability.
• Developing cost-effective, miniaturized spectrometers with wide spectral coverage is essential for point-of-care diagnostics and on-site inspection.

Purpose of the Study:

• To propose and simulate a novel concept for ultra-broadband miniaturized spectroscopy using non-resonant electro-optic modulation.
• To demonstrate a wide spectral tuning range and high spectral resolution for infrared applications.
• To present a low-cost alternative to conventional spectrometer designs.

Main Methods:

• Utilized a 45° groove micro-mirror with a silicon/dielectric/TCOs/metal stack for light modulation.
• Leveraged the epsilon-near-zero (ENZ) effect for spectral response tuning, relying on electron concentration rather than resonators.
• Simulated the device performance, predicting spectral tuning range and resolution.

Main Results:

• Predicted a remarkable spectral tuning range of 3000 nm.
• Achieved a predicted spectral resolution of 6 nm at 2.29 μm.
• Demonstrated strong ENZ mode confinement due to high refractive index contrast, enabling broad operation from near-infrared to mid-infrared.

Conclusions:

• The proposed non-resonant electro-optic modulation technique enables ultra-broadband miniaturized spectroscopy.
• This approach overcomes the limitations of resonator-based methods, offering a wider tuning range.
• The technology presents a promising, low-cost platform for portable optical sensing and on-site inspection applications.