Full-color reflectance-tunable filter based on liquid crystal cladded guided-mode resonant grating

Area of Science:

• Optics and Photonics
• Materials Science
• Liquid Crystal Displays

Background:

• Guided-mode resonant (GMR) gratings function as optical resonators, enabling strong reflection at specific wavelengths.
• Liquid crystals (LCs) are widely used in display technologies due to their tunable optical properties.
• Integrating LC with resonant structures offers potential for advanced optical filtering and modulation.

Purpose of the Study:

• To propose and design a tunable reflective GMR filter incorporating a 90° twisted nematic liquid crystal (TNLC).
• To demonstrate control over the filter's resonance wavelength and reflectance using external stimuli.
• To explore the potential of this hybrid GMR-LC filter for practical optical applications.

Main Methods:

• Fabrication of a GMR grating serving as both an optical resonator and an alignment layer for LC.
• Integration of a 90° TNLC layer, acting as an achromic polarization rotator, with the GMR grating.
• Characterization of the filter's spectral shift and transmittance tuning via angle of incidence and applied voltage.

Main Results:

• The hybrid GMR-LC filter exhibits a tunable spectral shift covering the entire visible spectrum (710 nm to 430 nm).
• Transmittance is precisely tunable to within 10 V across various resonance wavelengths.
• The designed filter is compact, features a simple structure, and is straightforward to fabricate.

Conclusions:

• The proposed tunable reflective GMR-LC filter offers broad spectral tunability and voltage-controlled transmittance.
• The device's compact and simple design facilitates practical implementation in various optical systems.
• This hybrid approach presents a promising solution for advanced optical filtering and polarization control applications.