Electrically tunable focusing microlens arrays based on polarization independent optical phase of nano liquid crystal droplets dispersed in polymer matrix are demonstrated. Such an optical medium is optically isotropic which is so-called an optically isotropic liquid crystals (OILC). We not only discuss the optical theory of OILC, but also demonstrate polarization independent optical phase modulation based on the OILC. The experimental results and analytical discussion show that the optical phase of OILC microlens arrays results from mainly orientational birefringence which is much larger than the electric-field-induced birefringence (or Kerr effect). The response time of OILC microlens arrays is fast~5.3ms and the tunable focal length ranges from 3.4 mm to 3.8 mm. The potential applications are light field imaging systems, 3D integrating imaging systems and devices for augment reality.
The feature that devices based on blue phase liquid crystals (BPLCs) is free of alignment layers. However, the alignment layers could affect the morphologies of BPLC-devices as well as the electro-optical properties. In this paper, we investigate the influence of alignment layers to crystal growth of polymer-stabilized blue phase liquid crystals (PS-BPLCs). Without alignment layer, PS-BPLCs experiences both homogeneous nucleation and heterogeneous nucleation, and the morphology appears in random crystal orientations. On the contrary, when the surfaces coated with alignment layers, a heterogeneous nucleation dominates during the crystal growth process. We further proposed a possible mechanism for crystal growth under different surface condition. This study provides an alternative method to control crystal growth of PS-BPLCs, which is for facilitating many PS-BPLCs based photonic devices.
This paper develops a hybrid power model consisting of a hydrogen production system, a proton exchange membrane fuel cell (PEMFC), a secondary battery, and solar cells. First, we integrate the system, and build a simulation model by MATLAB SimPowerSystem TM . The model parameters are adjusted by experimental data. Second, we define two performance indexes: system cost and reliability. Third, we consider a general household profile, and apply the model to discuss the effects on system costs and reliability by adjusting the sizes of the solar cells and battery. Based on the results, adjusting system components can significantly reduce system costs and improve system reliability. In addition, the developed hybrid PEMFC power model can effectively reduce the efforts for developing customized power systems.
Amongst many research applications, liquid crystal on Silicon spatial light modulators (LCoS SLM) are used in telecommunication applications as a beam steering device. The efficiency of the device is determined by the reflectivity of its backplane and the efficiency of the addressed phase function. While a dielectric mirror coating (DMC) helps improve the reflectivity, fringing field effects are also enhanced, leading to a decrease in diffraction efficiency. To minimize the thickness of the dielectric mirror, properly identifying the relevant parameter, which has an impact on the reflectivity of the backplane, is important. From experiment results and simulation results from the finite element method, we found the pixel shape as the relevant parameter. With the pixel shape taken into consideration, we show an example of optimized DMC.
'%3e%3cg id='b'%3e%3cpath id='a' stroke='%23000' stroke-width='2' d='M-6-25H6m-12 3H6m-12 3H6'/%3e%3cuse xlink:href='%23a' y='44'/%3e%3c/g%3e%3cpath stroke='%23fff' d='M0 17v10'/%3e%3ccircle r='12' fill='%23cd2e3a'/%3e%3cpath fill='%230047a0' d='M0-12A6 6 0 0 0 0 0a6 6 0 0 1 0 12 12 12 0 0 1 0-24z'/%3e%3c/g%3e%3cg transform='rotate(-123.69)'%3e%3cuse xlink:href='%23b'/%3e%3cpath stroke='%23fff' d='M0-23.5v3M0 17v3.5m0 3v3'/%3e%3c/g%3e%3c/svg%3e)
'/%3e%3cuse xlink:href='%23a' transform='rotate(60)'/%3e%3ccircle r='17' fill='%23000095'/%3e%3ccircle r='15' fill='%23fff'/%3e%3c/svg%3e)
