An efficient mid-infrared computational spectrometer based on synergistic microcavity-coupled photonic crystal...

Area of Science:

• Photonics
• Spectroscopy
• Materials Science

Background:

• Mid-infrared (MIR) spectroscopy is crucial for telecommunications, chemical sensing, and biomedical diagnostics.
• Existing spectrometers often lack the miniaturization, portability, and high resolution required for these advanced applications.
• Silicon photonics and computational methods offer pathways to develop compact, on-chip spectral analysis devices.

Purpose of the Study:

• To present a novel photonic spectrometer prototype utilizing a microcavity-coupled photonic crystal waveguide (MPCW) architecture for the mid-infrared region.
• To demonstrate a compact, high-resolution spectrometer leveraging synergistic integration of microcavity resonances and photonic crystal band edges.
• To showcase efficient thermal tuning and robust spectral reconstruction capabilities.

Main Methods:

• Fabrication of a photonic spectrometer based on microcavity-coupled photonic crystal waveguides (MPCW).
• Integration of non-uniform microcavity resonances with sharp photonic crystal band edges for defined spectral responses.
• Implementation of titanium microheaters for thermal tuning via the slow-light effect.
• Application of an alternating optimization approach for spectral reconstruction to reduce computational load.

Main Results:

• The MPCW spectrometer operates in the mid-infrared region with a resolution of 0.5 nm over a 100 nm bandwidth.
• Spectral retrieval of unknown spectra was achieved within several seconds, demonstrating high performance and robustness.
• Efficient thermal tuning enabled precise control over spectral response.
• The design proved scalable to other wavelength regimes by adjusting MPCW dimensions.

Conclusions:

• The developed MPCW spectrometer provides a compact, high-resolution, and robust solution for mid-infrared spectral analysis.
• The synergistic design and advanced reconstruction techniques overcome limitations of existing spectrometers.
• The scalable photonic crystal approach allows for versatile applications across different spectral regions.