Abstract
We report a high birefringence terphenyl liquid crystal mixture, designated as M3, for infrared phase modulation with special emphasis on mid-wave infrared (MWIR). In addition to high birefringence, M3 exhibits excellent UV stability, modest dielectric anisotropy, and a very broad nematic range. The high birefringence enables a thin cell gap to be used for achieving a 2π phase change while maintaining a high transmittance (T>98%) in the MWIR region. To achieve fast response time, we employed a polymer network liquid crystal using M3 with 2π phase change at λ = 4μm and 3.6-ms response time. This response time is about 100X faster than that of a nematic LC phase modulator.
Highlights
Liquid crystals (LCs) are an amazing class of soft materials which have been widely used in the visible [1, 2], infrared (IR) [3], millimeter wave [4], and terahertz [5, 6] spectral regions
We report a high birefringence terphenyl liquid crystal mixture, designated as M3, for infrared phase modulation with special emphasis on mid-wave infrared (MWIR)
We fabricated three polymer network liquid crystal (PNLC) devices with different polymer concentrations and studied how domain sizes affect the operation voltage and response time. We believe this first PNLC result is promising for MWIR applications, especially its response time is about 100X faster than that of the nematic LC host
Summary
Liquid crystals (LCs) are an amazing class of soft materials which have been widely used in the visible [1, 2], infrared (IR) [3], millimeter wave [4], and terahertz [5, 6] spectral regions. It has a Δn≈0.2 at λ = 5 μm and so to achieve a 2π phase change the required cell gap is 25 μm, which in turn leads to a slow response time (~1s). We report a terphenyl LC mixture, which shows high birefringence (Δn = 0.34 at λ = 514nm and Δn = ~0.253 at λ = 4μm), high transmittance (T>98%) in the MWIR region, and broad nematic range Using this mixture, we fabricated three PNLC devices with different polymer concentrations and studied how domain sizes affect the operation voltage and response time. We fabricated three PNLC devices with different polymer concentrations and studied how domain sizes affect the operation voltage and response time We believe this first PNLC result is promising for MWIR applications, especially its response time is about 100X faster than that of the nematic LC host
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