Dynamically tunable membrane metasurfaces for infrared spectroscopy and strong light-matter interactions

Area of Science:

• Photonics
• Spectroscopy
• Materials Science

Background:

• Mid-infrared spectroscopy is vital for biochemical sensing but limited by instrument size and sensitivity.
• Optical metasurfaces offer on-chip spectrometry potential but typically lack tunability.
• Static metasurfaces hinder the development of compact and versatile spectroscopic devices.

Purpose of the Study:

• To develop dynamically tunable silicon membrane metasurfaces for mid-infrared spectroscopy.
• To demonstrate high-Q transmissive resonances in the molecular fingerprint region.
• To enable sensitive, non-contact chemical analysis and explore strong light-matter interactions.

Main Methods:

• Utilized silicon's thermo-optical properties for dynamic tuning of metasurfaces.
• Engineered coupling-induced transparency (CIT) modes from quasi-bound states in the continuum (q-BICs) and surface lattice modes (SLMs).
• Employed non-contact chemical analysis of polymer films and investigated vibrational strong coupling.

Main Results:

• Achieved a spectral tuning rate of 0.06 cm^-1 K^-1 over a 23.5 cm^-1 range.
• Successfully detected characteristic absorption bands of polystyrene and poly(methyl methacrylate) without conventional spectrometers.
• Demonstrated a Rabi splitting of ~43 cm^-1, indicating vibrational strong coupling.

Conclusions:

• Established a reconfigurable photonic platform for mid-infrared spectroscopy and molecular sensing.
• The tunable metasurfaces offer spectral precision and strong field enhancement.
• Potential applications include compact spectrometers, advanced sensors, and programmable polaritonic devices.