Complex spatial light modulation capability of a dual layer in-plane switching liquid crystal panel

Complex spatial light modulator (SLM), which can simultaneously control the amplitude and phase of light waves, is a key technology for wide-range of wave-optic technologies including holographic three-dimensional displays. This paper presents a flat panel complex spatial light modulator that consists of dual in-plane switching liquid crystal panels with double-degrees of freedom of voltage inputs. The proposed architecture features single-pixel level complex light modulation enabling complex light modulation in entire free space, which is most contrast to conventional macro-pixel based complex modulation techniques. Its complex light modulation capability is verified with theoretical simulation and experimental characterization, and a three-dimensional holographic image reconstruction without conjugate noise. It is believed that the proposed flat panel complex SLM can be an essential device for a wide range of advanced wave optic technologies.

Characterization of the spatially anamorphic phenomenon and temporal fluctuations in high-speed, ultra-high pixels-per-inch liquid crystal on silicon phase modulator

High-birefringence liquid crystal (LC) in ultrathin LCOS panels was adopted to prepare high phase precision (mSTD =λ/50) and phase accuracy (mAPAE% ∼8%) with suppressed pixel-level crosstalk effects. In conjunction with optimized digital driving scheme, the zero order light loss was found directly related to the phase accuracy error. Meanwhile, the world's fastest pure phase modulation LCOS with a response time of ∼0.87 ms at 45 °C was also achieved. The low-temporal flicker (P-P ∼2.0%) with high-speed LC responses was demonstrated by applying new digital driving scheme. Finally, the 4K2 K LCOS-SLM (∼7000 PPI) was evaluated its difficulties and opportunities.

Low voltage and high resolution phase modulator based on blue phase liquid crystals with external compact optical system

Liquid crystal phase modulators are emerging as a new technological advancement, since they can be used for a wide range of applications. To improve their performance, polymer stabilized blue phase liquid crystal (PS-BPLC) phase modulators with fast response time and accurate phase profile become a necessary. Here, we proposed a facile PS-BPLC phase modulator to achieve particularly low voltage and high resolution. By employing a specific external compact optical system setup, the driving voltage is reduced to 26.09V to obtain 2π phase change at the wavelength of 532 nm. An accurate numerical modeling is also conducted to provide a systematic investigation of the fringing electric field effect to the performance of high resolution PS-BPLC phase modulator. The wavefront distortion caused by the fringing electric field can be automatically compensated to generate accurate phase profile for fast response liquid crystal phase modulator. This work provides a new protocol to realize liquid crystal on silicon based fast response and high resolution phase modulator.

Polarization-independent phase modulation using a blue-phase liquid crystal over silicon device

Liquid crystal over silicon (LCoS) spatial light modulator technology has become dominant in industries such as pico-projection, which require high-quality reflective microdisplays for intensity modulation of light. They are, however, restricted from being used in wider optical applications, such as computer-generated holography, adaptive optics, and optical correlation, due to their phase modulation ability. The main drawback of these devices is that their modulation is based on simple planar or twisted nematic liquid crystals, which are inherently slow mechanisms due to their viscoelastic properties. Their use is also limited due to fact that the phase modulation is dependent on the state of polarization of the illumination. In this paper, we demonstrate that a polymer-stabilized blue-phase liquid crystal can offer both phase modulation and high speed switching in a silicon backplane device which is independent of the input polarization state. The LCoS device shows continuous phase modulation of light with a submillisecond switching time and insensitivity to the input light polarization direction. This type of phase modulation opens up a whole new class of applications for LCoS technology.

Diffraction based phase compensation method for phase-only liquid crystal on silicon devices in operation

A method to measure the optical response across the surface of a phase-only liquid crystal on silicon device using binary phase gratings is described together with a procedure to compensate its spatial optical phase variation. As a result, the residual power between zero and the minima of the first diffraction order for a binary grating can be reduced by more than 10 dB, from -15.98 dB to -26.29 dB. This phase compensation method is also shown to be useful in nonbinary cases. A reduction in the worst crosstalk by 5.32 dB can be achieved when quantized blazed gratings are used.

High speed liquid crystal over silicon display based on the flexoelectro-optic effect

One of the key technologies to evolve in the displays market in recent years is liquid crystal over silicon (LCOS) microdisplays. Traditional LCOS devices and applications such as rear projection televisions, have been based on intensity modulation electro-optical effects, however, recent developments have shown that multi-level phase modulation from these devices is extremely sought after for applications such as holographic projectors, optical correlators and adaptive optics. Here, we propose alternative device geometry based on the flexoelectric-optic effect in a chiral nematic liquid crystal. This device is capable of delivering a multilevel phase shift at response times less than 100 microsec which has been verified by phase shift interferometry using an LCOS test device. The flexoelectric on silicon device, due to its remarkable characteristics, enables the next generation of holographic devices to be realized.