A polarization-independent phase-only liquid crystal (LC) phase modulator using a double-layered structure is demonstrated. Two orthogonal LC layers are separated by two ultra-thin anisotropic polymer films. The anisotropic polymeric films not only separate the LC layers but also provide good molecular alignment. As a result, a polarization-independent phase modulator with 2pi phase shift is achieved at 9Vrms and 8.1pi at 40Vrms using a 12-microm-thick E7 LC layers. This operating voltage is ~10X lower than that using a conventional 0.3-mm-thick glass separator.

We demonstrate a variable optical attenuator (VOA) at lambda=1.55 microm using a sheared polymer network liquid crystal (SPNLC). The SPNLC exhibits a fast response time and weak wavelength dependency. Comparing with other polymer-stabilized liquid crystals, the SPNLC has lower driving voltage and negligible light scattering loss when the wavelength exceeds 700 nm. A reflection type VOA with ~0.24 ms response time and -32 dB dynamic range is demonstrated at room temperature and 35 Vrms voltage.

An axially-symmetric sheared polymer network liquid crystal (SPNLC) device is demonstrated and its performances characterized. Through analyzing the structure of this axially-symmetric SPNLC, we constructed a 3-D model to explain the observed phenomena. The simulation results agree well with the experiment. Two potential applications of such an axially-symmetric SPNLC, namely tunable-focus negative lens and spatial polarization converter, are discussed.

Fast-response, polarization-independent, and hysteresis-free phase-only modulation using a normal-mode polymer-stabilized cholesteric texture ͑PSCT͒ is demonstrated. Although the remaining phase change in the high-voltage regime is small, it is still useful for making microdevices. Polarization-independent tunable-focus microlens arrays using such a PSCT are demonstrated.

A fast phase modulator based on ferroelectric liquid crystal (FLC) is demonstrated and its performances characterized. For uniform alignment and pure phase modulation, we propose a new FLC device configuration using short helical pitch material and homeotropic alignment structure. This device is driven by periodic in-plane electrode stripes implemented on the surface of both cell substrates. As a result, we have obtained large phase modulation (> 2pi at lambda=1.55 microm) and fast response (< 200 microsec).

The surface pining effects on phase separation dynamics of polymer-dispersed liquid crystals (PDLCs) with thin cell gaps are demonstrated. Comparing various boundary conditions, the inner surfaces of the substrates with or without polyimide layers [but no rubbing] cannot provide enough anchoring force, so in either case the liquid crystal (LC) droplets flow and coalesce to form larger and less uniform droplets. However, if the inner surfaces of the substrates are coated with rubbed polyimide layers with anchoring energy >1x10-4 J/m2, almost all the nucleated LC droplets grow at a fixed position during phase separation. The appearance of the coalescence is not obvious and the formed LC droplets are relatively uniform. The surface anchoring has a significant effect on the morphology of PDLCs.

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Two high performance reflective guest‐host liquid crystal displays (GH LCDs) using a dual‐frequency liquid crystal (DFLC) gel and a negative liquid crystal (NLC) gel are developed. These polarizer‐free GH‐LCDs exhibit ∼50% reflectance, ∼200:1 contrast ratio, and <5 ms response time. Such reflective LCDs can also be used in double cell gap transflective displays.