Small phase pattern 2D beam steering and a single LCOS design of 40 1 × 12 stacked wavelength selective switches

Electrically tuned active metasurface towards metasurface-integrated liquid crystal on silicon (meta-LCoS) devices

Active metasurfaces add a new dimension to static metasurfaces by introducing tunability, and this has received enormous attention from industry. Although various mechanisms have been proposed over the past few years in literature, solutions with good practicality are limited. Liquid crystal (LC)-based active metasurface is one of the most promising approaches due to the well-established LC industry. In this paper, an electrically tunable active metasurface was proposed and experimentally demonstrated using photoaligned nematic LC. The good quality of the LC photoalignment on the metasurface was demonstrated. Tunable transmission was obtained for telecommunication C band and the modulation depth in transmission amplitude of 94% was realized for 1530 nm. Sub-millisecond response time was achieved at operating a temperature of 60°C. The progress made here presents the potential of LC-based active metasurfaces for fast-switching photonic devices at optical communication wavelengths. More importantly, this work lays the foundations for the next-generation liquid crystal on silicon (LCoS) devices that are integrated with metasurfaces (meta-LCoS).

Sub-millisecond switching of multi-level liquid crystal on silicon spatial light modulators for increased information bandwidth

Sub-millisecond response time with a refresh rate higher than 2000 frames per second (fps) and no degradation of the contrast ratio or diffraction efficiency is demonstrated in working liquid crystal on silicon (LCOS) spatial light modulators (SLMs) with 8-bit grey levels of amplitude and phase modulations. This makes possible to achieve an information bandwidth of about 190 Gb s^-1 with a 4k LCOS operating at 10-bit phase modulation levels. The normalised contrast stays at almost the unit level for a frame rate up to 1700 fps and at higher than 0.9 for 2500 fps. The diffraction efficiency stays above -1.0 dB for a frame rate up to 2400 fps. Such a fast response allows us to eliminate image blurring in replaying a fast movie.

Improvements of phase linearity and phase flicker of phase-only LCoS devices for holographic applications

Significant phase distortion corrections were achieved by optimizing the digital driving patterns of phase-only liquid crystal on silicon devices for digital holographic applications. Nearly perfect phase linearity and phase flicker of 0.09% over 256 addressed phase levels in respect to the total modulation range of 2π were realized, enabling a meaningful increase of phase levels from 8 bits (256 levels) to 9 bits (512 levels). Tests were carried out to evaluate the qualities of optically reconstructed holographic images with reduced phase flicker and optimized phase linearity, and an increase of 17.7% in the root-mean-square contrast was demonstrated.

Beyond the display: phase-only liquid crystal on Silicon devices and their applications in photonics [Invited]

Existing for almost four decades, liquid crystal on Silicon (LCOS) technology is rapidly growing into photonic applications. We review the basics of the technology, from the wafer to the driving solutions, the progress over the last decade and the future outlook. Furthermore we review the most exciting industrial and scientific applications of the LCOS technology.

Programmable spectral processor based on spatial polarization manipulation with liquid crystal on silicon

We experimentally demonstrate a novel liquid crystal on silicon (LCoS)-based programmable spectral processor, including two cascaded photonic configurations, to realize the state of polarization (SOP) manipulation in the spatial and spectral domain. As the final SOP at each wavelength is linear polarization with a manageable polarization direction, a broadband linear polarizer is used to filter the undesired wavelengths. The polarization manipulation only needs to be implemented along the dispersion direction with a 1D-LCoS. The programmable spectral processor can experimentally reach an intensity modulation depth of 46.4 dB with less than 1 dB polarization-dependent loss (PDL). Moreover, arbitrary power spectral distribution can be obtained with around 40 dB channel isolation. In particular, our experimental results verify that the proposed setup can achieve the adjustable central wavelength and tunable filtering at a resolution of 0.08 nm.

Electrowetting-actuated multifunctional optofluidic lens to improve the quality of computer-generated holography

This paper presents an electrowetting-actuated multifunctional optofluidic (EAMO) lens to improve the quality of computer-generated holography (CGH). A unique structure of the EAMO lens based on electrowetting effect is designed. When the electrodes of the EAMO lens are applied on different voltages, the functions of focal length change and aperture change can be achieved. Then the proposed lens is used in the reproduction system of the CGH due to the multiple functions. The experimental results show that the CGH with zoom function can be realized and undesirable light can be eliminated due to the unique structure of the EAMO lens. The focal length changes can be varied from 11.6 cm to + ∞ and -∞ to -150.6 cm. The aperture size changes can be varied from 10.1 cm to 6.7 cm. By using the proposed EAMO lens, high-quality CGH can be realized without moving the position of any components mechanically, while the setup of the CGH is greatly simplified.