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Electrically Tunable Defect-Mode Wavelengths in a Liquid-Crystal-in-Cavity Hybrid Structure in the Near-Infrared
Guan-Fu Sung1, Shun-Yi Chiu2, Yi-Cheng Chang3
1College of Photonics, National Yang Ming Chiao Tung University, Guiren District, Tainan 711010, Taiwan.
Materials (Basel, Switzerland)
|April 28, 2023
Summary
This study introduces a tunable near-infrared (NIR) spectrometer component using a liquid crystal (LC) photonic crystal (PC). A novel PC/LC structure achieves wide wavelength tunability with low voltage, ideal for spectrometer development.
Area of Science:
- Photonics
- Materials Science
- Spectroscopy
Background:
- Development of tunable optical components is crucial for advanced spectroscopic applications.
- Liquid crystals (LCs) offer electro-optic tunability, making them attractive for photonic devices.
- Photonic crystals (PCs) provide unique light manipulation properties within specific wavelength ranges.
Purpose of the Study:
- To propose and validate a novel tunable wavelength component for near-infrared (NIR) spectrometers.
- To investigate a hybrid photonic crystal (PC) structure incorporating liquid crystals (LCs).
- To demonstrate wavelength tunability via electrical control of LC molecules within a PC cavity.
Main Methods:
- Utilized a liquid crystal-in-cavity structure as a hybrid photonic crystal (PC).
- Employed the 4x4 Berreman numerical method for simulating defect mode behavior and cell thickness relationships.
- Experimentally investigated defect mode wavelength shifts under varying applied voltages.
Main Results:
- Demonstrated that altering LC molecule tilt angle electrically tunes transmitted photon wavelengths as defect modes within the photonic bandgap (PBG).
- Identified a 7.9 μm thick PC/LC cell requiring only 2.5 Vrms to cover the 1250-1650 nm NIR range.
- Confirmed low power consumption and wide spectral coverage for the developed tunable component.
Conclusions:
- The proposed tunable PC/LC structure is a viable core component for NIR spectrometers and monochromators.
- Achieved efficient wavelength tunability across the entire NIR spectrum with minimal operating voltage.
- The hybrid photonic crystal approach offers a promising pathway for developing compact and power-efficient optical modules.
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