Performance enhancement using a stable low-pretilt molecular configuration and a novel driving method for optically compensated bend liquid crystal devices.

A stable low-pretilt molecular configuration (SLPMC) is successfully developed in optically compensated bend (OCB) liquid crystal (LC) devices by simultaneously employing the curing voltage and surface-anchored crosslinking monomer during the polymerization process. For the SLPMC OCB cell with the low-bend state, the warm-up voltage making the LC molecules reorient from the splay to the bend state is annihilated, and the transient twist state occurring as the driven LC molecules recover from the bend to the splay state is also eliminated. In addition, with the novel driving method selecting the specific driving point, the proposed SLPMC OCB cell not only exhibits a good response performance, but also outputs a higher light transmittance, which is superior to the conventional OCB and no-bias-bend cells. This Letter demonstrates an effective SLPMC fabrication method, and points out the significant contributions of SLPMC on the electro-optical properties, which will benefit and enhance the performance design in OCB-based applications.

Effects of the vertically switching electric field on the photoelectric properties of polymer-stabilized blue-phase liquid crystal cells using the director model.

This study uses the director model to analyze the optoelectronic properties of polymer-stabilized blue-phase liquid crystal (PS-BPLC). The director model revealed a linear relationship of refractive index change and the cosine squared of the angle between the LCs and the direction of the electric field. Moreover, we employed simulations based on the Kerr effect and compared the results with those of the director model. The simulation results also show high consistency with real circumstances. Consequently, it can be of great help to design BPLC displays that can be applied to adopting better strategies for developing next-generation LCD devices.

Effects of cell gap on the optoelectronic properties of pure blue-phase liquid crystal devices: estimating the Kerr constant.

In this study, the Kerr constant of pure blue-phase liquid crystal (BPLC) without polymer doping at room temperature and the optoelectronic properties dependent on the cell thickness are explored. The relation between the phase and the voltage in oblique incident light was measured via a reasonable vertical electric field for different thicknesses of BPLC cells. It was found that the Kerr constant formula can be amended with the functions related to the cell gap. This study demonstrates a method to estimate the Kerr constant, especially for cells within a small electrical field, which will benefit optoelectronic applications.

Radially realigning nematic liquid crystal for efficient tuning of microring resonators.

The efficient tuning of microring resonator with the radially realigning nematic liquid crystal (NLC) cladding is presented. By applying the voltage on the in-plane annular electrodes, the produced electric field realigns the homeotropically-aligned NLC in the radial direction. Under the voltage sufficient for 90° NLC reorientation, the guided mode senses the consistent cladding index distribution along the microring waveguide with the maximal index change equal to the optical anisotropy of NLC. The resultant tuning of the resonant wavelength has a blue shift of 23.1nm for the TM mode and a red shift of 10.1nm for the TE mode. The tuning rates for the TM and TE modes are -1.95nm/V and 0.90nm/V. The proposed microring resonator owns the excellent features of wide tuning ranges and high tuning rates for the TM and TE modes.

Simulation of the in-plane-switching blue-phase liquid crystal using the director model.

We analyze the non-uniform electric field distribution in an in-plane-switching blue phase liquid crystal (IPS-BPLC) cell and use the director model to simulate the electro-optical properties of an IPS-BPLC cell using a commercial simulator. The calculated results are in good agreement with the experimental data.

Wide tuning of SiN microring resonators by auto-realigning nematic liquid crystal.

We present wide electrical tuning of microring resonators with auto-realigned nematic liquid crystal (NLC) cladding. By applying electric field, homeotropically-aligned negative Δε NLC with non-rubbed alignment layers is auto-realigned along the microring waveguide due to the protruding of the ridge structure. The consistent cladding index distribution along the microring waveguide produces effective tuning of the resonant wavelength. It achieves a large tuning range of 13nm for TM mode and 2.1nm for TE mode. The NLC reorientation characteristics are investigated by minimizing Oseen-Frank energy. The proposed microring resonator owns the features of large tuning range and bi-polarization wavelength tuning.

Use of modal interference for probing birefringence induced in a bent optical fiber.

We report a novel method that utilizes two lowest-order modes, HE(11) and TE(01), to probe birefringence induced in a bent circular-core optical fiber. The interference patterns of the two modes are examined by using a polarizer at the fiber output end. The contrast that is extracted from the interference pattern is periodically modulated as a function of phase retardation between the two modes, while the shift of the contrast function shows a strong dependence on the fiber birefringence as the polarizer rotates. Theoretical description followed by the test results demonstrates the feasibility of the method.

Use of liquid-crystal-clad fiber as a modal filter for a two-mode fiber-optic interferometer.

A novel two-mode fiber-optic interferometer employing a liquid-crystal-clad fiber as a modal filter is proposed. The liquid-crystal-clad fiber can guide one of the second-order modes, TE01, and leak out the other TM01 and HE21 modes. Thus two spatial modes, fundamental mode HE11 and second-order mode TE01 serve as the two arms of the interferometer to detect an external perturbation. The experimental results obtained when this interferometer was used to sense temperatures ranging from 20 to 100 degrees C are demonstrated.