Spectral encoding based on narrowband/broadband modulations of QBIC for computational spectral imaging

Area of Science:

• Nanophotonics
• Computational Imaging
• Optical Engineering

Background:

• Accurate spectral reconstruction is vital for nanophotonic computational spectral imaging.
• Conventional encoders with broadband modulation limit spectral resolution and fidelity for narrowband features.

Purpose of the Study:

• To propose a simultaneous narrowband and broadband spectral encoder using quasi-bound states in the continuum (QBIC).
• To overcome the resolution limitations of conventional nanophotonic encoders.

Main Methods:

• Designed a QBIC structure with tunable lateral dimensions to control electric/magnetic dipole resonances.
• Implemented simultaneous narrowband and broadband modulation by combining QBIC resonances with broadband transmittance modulation.
• Evaluated performance against a typical multilayer film modulator in real-world scenarios.

Main Results:

• Achieved simultaneous narrowband and broadband spectral modulation across the operating wavelength range.
• Enhanced the average peak signal-to-noise ratio of reconstructed images by 5.33 dB.
• Reduced the error of full width at half maximum by approximately 5 nm compared to conventional modulators.

Conclusions:

• The proposed QBIC-based spectral encoder overcomes resolution limitations of conventional modulators.
• Combined broadband and narrowband modulation offers new possibilities for high-accuracy, miniaturized computational imaging.
• This approach enhances spectral reconstruction fidelity, particularly for objects with narrowband spectral features.