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This paper presents the development of liquid crystal on silicon (LCOS) technology aimed at enhancing the image quality and reliability of projectors. Additionally, we introduce an 8K LCOS panel with a pixel pitch of 2.6 μm. Furthermore, we discuss the application prospects of the developed phase‐only spatial light modulator. [ABSTRACT FROM AUTHOR]

This developed 1.2‐inch 4K2K LCOS with 76.0 lp/mm spatial resolution can still achieve high phase accuracy and obviously enlarge field‐of‐viewing (FOV) angle compared with previous 0.55‐inch 2K1K LCOS. The holographic image quality within phase‐only LCOS not only can be improved by using higher phase accuracy and compensation technologies, but also can realize the real 3D imaging into near‐eye displays to avoid the VAC phenomena. In addition to, the holographic 4K2K LCOS (26.6mm x 15.8mm) optical design can achieve lighter optical engine and reconstructed square (26.6mm x 26.6mm) image per eye, so that it has advantages of more feasible driving condition and cost competition. As high‐speed technologies of display electronics, liquid crystal, and optical algorithm were gradually mature, the above 1.2" phase‐only LCOS with both high pixel resolution and smaller pixel pitch will be another choice into the VR & MR headsets utilized video see‐through (VST) method. Meanwhile, the 1.2" 4K2K LCOS with enhanced FOV can be alternative scheme for AR glasses using optical see‐through (OST) method before the trade‐off between volume, brightness, and FOV angle are resolved. [ABSTRACT FROM AUTHOR]

The relationship among the liquid crystal thickness, fringing field effect and diffractive efficiency of the Liquid Crystal on Silicon (LCoS) device is studied in this paper, by measuring two prepared LCoS devices working at 1550nm with liquid crystal thickness of 5µm and 7µm respectively. The width of the fly back region of the LCoS devices was measured under microscopy to characterize the effect of the fringing field effect. The results demonstrated that in most cases, the smaller the thickness of the liquid crystal layer, the narrower the fly back region, and the higher the diffractive efficiency, but the direction of the grating may also affect the width of the fly back region to a certain extent. [ABSTRACT FROM AUTHOR]

Holographic display enabled by performing both amplitude modulation (AM) and phase modulation (PM) in a single Liquid Crystal on Silicon (LCoS)‐based Spatial Light Modulator (SLM) is introduced. Light propagation is manipulated in two different directions to perform both AM and PM via liquid crystals alignment layer which can be based on technologies by using photoalignment, nano‐imprint lithography (NIL), or unique over‐driving across Liquid Crystal (LC) layer of Vam‐Vpm method which are described and proved to be effective to tune incident light, control the polarization and propagation of the light entering the liquid crystals of a single LCoS‐based SLM (LCoS‐SLM) device. These methods enable holographic display and to alleviate the issues in using two separated SLMs trying to achieve the same. Further, the design techniques and methods to suppress adjacent pixels' crosstalk due to fringe field effect (FFE) [1] in 2D array are amenable to ensure higher resolution with pixel pitch down to 1¼m for compact size and higher pixel numbers beyond 8K×4K. It mitigates to reduce chores of pixel‐to‐pixel alignment, and to enhance image clarity and quality within a single LCoS‐SLM. It will be applicable to enable holographic display with such unique LCoS‐SLM particularly for AR/VR/MR smart glasses applications [18] [19] [20] once being fabricated in the future. [ABSTRACT FROM AUTHOR]

Wavelength selective switches (WSSs) are key components in commercial reconfigurable optical add/drop multiplexer systems that are essential for future wavelength‐division multiplexing (WDM) networks. With rapidly increasing data transmission, there is a demand for high‐capacity WSSs. However, in a WSS, the number of channels, which is related to the ratio of its band coverage relative to spectral resolution, is limited within a certain range, since the 1D dispersion of the grating fails to utilize the 2D selectivity of the liquid crystal on silicon (LCoS) pixel array in the "disperse and select" architecture.. To surpass this limitation, here a virtually imaged phased array (VIPA) is employed into the WSS system to expand 1D‐dispersion into 2D space in order to fully utilize the 2D selectivity of LCoS. According to the experimental results, this VIPA‐grating‐based 2D WSS approach enables a spectral resolution that can be narrowed to 1.57 GHz (18 times improvement from 1D WSS, and massive (>1600) WDM channels can be predicted) and ultrabroadband spectral coverage across the S‐, C‐, and L‐bands of 20 THz. The data communication performance of the 2D WSS is also tested. [ABSTRACT FROM AUTHOR]

High‐performance beam‐steering devices play a crucial role for optical wireless communication (OWC), which can meet the demand for increasing number of wireless mobile devices and emerging high‐speed multimedia applications. Conventional beam‐steering optical components like spatial light modulator and digital micromirror device are limited to realize a small steering angle (typ. several degrees), thus dramatically limits the spatial scope of OWC. Herein, a beam‐steering metadevice utilizing an ultracompact metasurface assisted with a spatial light modulator is presented, which can significantly increase the beam‐steering angle without at the cost of complicated optical setup like conventionally used angle magnifier. Based on the actively tunable beam‐steering metadevice, an intelligent bidirectional optical broadcasting communication system is designed and experimentally demonstrated, which exhibits nine broadcasting areas covering a large field‐of‐view of 20° × 20°, with user‐defined dynamic beam‐steering ability in each area, and each user has a data rate of 10 Gbps for both upstream and downstream transmission. The proposed metadevices can meet the demand of intelligent optical wireless communication which requires both high‐performance and low‐cost for practical purpose, under currently available technical architectures. [ABSTRACT FROM AUTHOR]

For wavefront corrector (WFC) based on liquid crystal on silicon (LCoS), existing good phase change linearity and fast response are the key requirements to achieve fast and high-accuracy performance. Aiming at this, refreshing manner and period is optimised firstly to minimise the temporal phase fluctuation derived from pixels phase updating. Grey bit of applied voltage used for LCoS-WFC is also optimised to form better phase linearity and phase modulating accuracy, whether the LCoS is under over-driving method or not. After optimisation, both the phase error derived from poor phase linearity and the temporal phase fluctuation derived from improper refreshing process could be reduced by nearly one time, and the phase modulated step can be reduced to 80% of that before optimisation. This result can not only save significant LCoS design costs, but also provide full design guidance for future improvement of LCoS WFC. [ABSTRACT FROM AUTHOR]

This communication aims to address the recent surge of interest in reconfigurable intelligent surfaces (RISs) among both academic and industrial communities, which has largely neglected the historical developments of two other underpinning technologies, i.e., liquid crystal on silicon (LCOS) and liquid crystal reflectarray antenna (LCRA). Specifically, this communication focuses on the state of the art of LC-RIS, highlighting the unique features of this newly raised enabling technology for post-5G (6G) networks and comparing it to LCOS, which operates at different frequencies and is suited to different use cases. Drawing on insights from existing knowledge of LCOS and LCRA, opportunities and challenges are explored for LC-RIS's technical advancements in enhancing the coverage, capacity, and energy efficiency of wireless networks. In particular, the development status and roadmap of LC-RIS in China is reviewed. [ABSTRACT FROM AUTHOR]

The classical polarimetric method has been widely used in liquid crystal on silicon (LCoS) phase measurement with a simple optical setup. However, due to interference caused by LCoS cover glass reflections, the method lacks accuracy for phase uniformity measurements. This paper is aimed at mathematically analyzing the errors caused by non-ideal glass reflections and proposing procedures to reduce or eliminate such errors. The measurement is discussed in three conditions, including the ideal condition with no reflections from the LCoS cover glass, the condition with only the front reflection from the cover glass, and the condition with only the back reflection from the cover glass. It is discovered that the backward reflection makes the largest contribution to the overall measurement error, and it is the main obstacle to high-quality measurements. Several procedures, including optical alignment, LC layer thickness measurement, and phase estimation method, are proposed, making the uniformity measurement more qualitative and consistent. [ABSTRACT FROM AUTHOR]

High‐performance beam‐steering devices play a crucial role for optical wireless communication (OWC), which can meet the demand for increasing number of wireless mobile devices and emerging high‐speed multimedia applications. Conventional beam‐steering optical components like spatial light modulator and digital micromirror device are limited to realize a small steering angle (typ. several degrees), thus dramatically limits the spatial scope of OWC. Herein, a beam‐steering metadevice utilizing an ultracompact metasurface assisted with a spatial light modulator is presented, which can significantly increase the beam‐steering angle without at the cost of complicated optical setup like conventionally used angle magnifier. Based on the actively tunable beam‐steering metadevice, an intelligent bidirectional optical broadcasting communication system is designed and experimentally demonstrated, which exhibits nine broadcasting areas covering a large field‐of‐view of 20° × 20°, with user‐defined dynamic beam‐steering ability in each area, and each user has a data rate of 10 Gbps for both upstream and downstream transmission. The proposed metadevices can meet the demand of intelligent optical wireless communication which requires both high‐performance and low‐cost for practical purpose, under currently available technical architectures.

The vertical alignment technology by processing sputtered ZnO film for LCD with ozone is proposed in this paper. The prepared ZnO thin films were treated with ozone in the ultraviolet cleaning machine through polarizer. The wettability of the treated ZnO films switched to hydrophobicity, reaching a contact angle of 92°. With the prepared ZnO film as the alignment layer in the transmissive LCD cell, the vertical alignment (VA) can be realized. The results demonstrated that the test cells not only possessed the photo‐electronic characteristics of traditional VA liquid crystal cells but also had a smaller threshold voltage of 1.95V. In addition, the ZnO films are applied into character display successfully since the VA test cell has a high contrast ratio. [ABSTRACT FROM AUTHOR]

The classical polarimetric method has been widely used in Liquid Crystal on Silicon (LCoS) phase depth measurement with a simple optical setup. However, the current method does not provide sufficient accuracy to measure the phase uniformity due to interference caused by LCoS cover glass reflections. This paper is aimed at mathematically analyzing the errors caused by non‐ideal glass reflections, and proposing procedures to reduce or eliminate such errors. The measurement is discussed in three conditions, including an ideal condition with no reflections off the LCoS cover glass, a second condition with only forward reflection off the cover glass and a third condition with only backward reflection off the cover glass. It is discovered that the backward reflection has the largest contribution to the overall measurement error, and is the main obstacle to high‐quality measurements. Several procedures including optical alignment, gap thickness measurement and phase estimation based on gap thickness are proposed, making the uniformity measurement more qualitative and consistent. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Liquid Crystal & Displays is the property of Chinese Journal of Liquid Crystal & Displays and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The pulsed current has been proposed as a promising battery charging technique to improve the charging performance and maximize the lifetime for lithium-ion (Li-ion) batteries. However, the effect of the pulsed current charging is inconclusive due to the changeable current mode and conditions. This article systematically investigates the effect of various pulsed current charging modes, i.e., positive pulsed current mode, pulsed current-constant current mode, negative pulsed current mode, alternating pulsed current mode, sinusoidal-ripple current mode, and alternating sinusoidal-ripple current mode on battery performance. Moreover, a comprehensive analysis of the frequency impact on the quality of the current mode is performed. The current modes in this work are evaluated considering the maximum rising temperature, discharging capacity, and charging speed according to experimental results. Furthermore, this work provides guidance for developing pulsed current charging strategies to satisfy future charging requirements. [ABSTRACT FROM AUTHOR]

Holographic generation of beam spot array with high uniformity have been extensively investigated while existing methods cannot combine high quality and tunability. This paper demonstrated a method to generate beam spot array by using phase-only liquid crystal on silicon (LCOS) device. The proposed method is highly flexible and tolerant to the defects within the LCOS device. The uniformity deviation of the speckle array can be limited to within ±5% in the numerical simulation and the experimental results agreed well with the simulation results. [ABSTRACT FROM AUTHOR]

The classical polarimetric method has been widely used in liquid crystal on silicon (LCoS) phase measurement with a simple optical setup. However, due to interference caused by LCoS cover glass reflections, the method lacks accuracy for phase uniformity measurements. This paper is aimed at mathematically analyzing the errors caused by non-ideal glass reflections and proposing procedures to reduce or eliminate such errors. The measurement is discussed in three conditions, including the ideal condition with no reflections from the LCoS cover glass, the condition with only the front reflection from the cover glass, and the condition with only the back reflection from the cover glass. It is discovered that the backward reflection makes the largest contribution to the overall measurement error, and it is the main obstacle to high-quality measurements. Several procedures, including optical alignment, LC layer thickness measurement, and phase estimation method, are proposed, making the uniformity measurement more qualitative and consistent.

This communication aims to address the recent surge of interest in reconfigurable intelligent surfaces (RISs) among both academic and industrial communities, which has largely neglected the historical developments of two other underpinning technologies, i.e., liquid crystal on silicon (LCOS) and liquid crystal reflectarray antenna (LCRA). Specifically, this communication focuses on the state of the art of LC-RIS, highlighting the unique features of this newly raised enabling technology for post-5G (6G) networks and comparing it to LCOS, which operates at different frequencies and is suited to different use cases. Drawing on insights from existing knowledge of LCOS and LCRA, opportunities and challenges are explored for LC-RIS’s technical advancements in enhancing the coverage, capacity, and energy efficiency of wireless networks. In particular, the development status and roadmap of LC-RIS in China is reviewed.

The increase in communications network traffic has led to a demand for a larger transmission capacity. To meet this demand, the combination of wavelength division multiplexing (WDM) and space-division multiplexing (SDM) is being extensively investigated. Among various SDM systems, that based on multi-core fiber is attractive because network flexibility increases while it maintains the transmission capacity to be enlarged in proportion to the number of SDM channel number. However, problems arise because the number of input/output ports increases dramatically in optical nodes. To solve these problems, there is a novel optical configuration technology, the spatial and planar optical circuit (SPOC), which makes the integration of multiple WSSs and filters possible. The SPOC platform has been used to achieve variety of devices such as optical dispersion compensation and WSSs. One of the great advantages of SPOC platform is that we can integrate multiple optics of WSSs in a module, which contribute to miniaturization of devices. In this paper, we review the devices for SDM networks, which are realized with SPOC platform including WSS arrays, wavelength cross-connects (WXCs), multi-channel optical performance monitors, and its related technology. [ABSTRACT FROM AUTHOR]

Current 2D windshield head-up displays can lead to driver distractions due to a shift of gaze from the road towards a small area of the windshield. Customizable mixed reality real-time head-up displays can increase safety in transportation due to the holographic road obstacles being aligned with the road scene. Based on accelerated parallel processing algorithms, a 4K spatial light modulator, virtual Gabor lenses and a He-Ne laser, 3D holographic road signs appear within 1.15 seconds in the driver’s gaze on the road.

In this paper, we propose a holographic zoom system based on two adjustable lenses. Different from the traditional holographic system, a digital conical lens and a liquid lens are used as the zoomable lenses. The liquid lens with large effective image aperture is designed and produced by a 3D printer. By mechanically controlling the curvature of the liquid-liquid surface, the focal length of the liquid lens can be changed easily. Compared with the other lenses, the conical lens has a larger focal depth. By encoding the phase information of the conical lens on the liquid crystal on silicon, the focal length and focal depth of the conical lens can be adjusted easily. The liquid lens and conical lens cooperate with each other so as to realize the high quality of holographic zoom projection. With such a system, the size and depth of the reconstructed image can be changed easily according to the requirement. Experimental results verify the feasibility of the proposed system.

Holographic generation of beam spot array with high uniformity have been extensively investigated while existing methods cannot combine high quality and tunability. This paper demonstrated a method to generate beam spot array by using phase-only liquid crystal on silicon (LCOS) device. The proposed method is highly flexible and tolerant to the defects within the LCOS device. The uniformity deviation of the speckle array can be limited to within ±5% in the numerical simulation and the experimental results agreed well with the simulation results.

A hybrid phase modulation of liquid crystal on silicon (LCOS) was proposed to optimize the crosstalk and diffraction efficiency of the ports with different deflection angle of wavelength selective switch(WSS). With phase profile of high phase depth, the ports of small deflection angle may achieve high diffraction efficiency and low crosstalk. And the ports of large deflection angle may achieve low crosstalk and relative high diffraction efficiency with phase profile of low phase depth. The hybrid phase modulation shows the great potential application of multi‐port WSS. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Liquid Crystal & Displays is the property of Chinese Journal of Liquid Crystal & Displays and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Supercontinuum (SC) lasers combine a broadband light spectrum with the unique properties of single-mode lasers. In this work we present an optical system to spectrally filter a SC laser source using liquid-crystal on silicon (LCoS) spatial light modulators (SLM). The proposed optical system disperses the input laser and the spectrally separated components are projected onto the LCoS-SLM, where the state of polarization of each wavelength is separately modulated. Finally, recombining the modulated spectral components results in an output laser source where the spectrum can be controlled dynamically from a computer. The system incorporates two branches to independently control the visible (VIS) and the near infrared (NIR) spectral content, thus providing a SC laser source from 450 to 1,600 nm with programmable spectrum. This new ability for controlling at will the wide spectra of the SC laser sources can be extremely useful for biological imaging applications.

This article demonstrates the design, assembly, optimisation, and characterisation of 24 [1 × 12] wavelength selective switches (WSSs) based on a single set of optics and a 4k liquid crystal on silicon (LCoS) device. The average insertion loss was measured to be 8.4 dB with an average crosstalk level of 26.9 dB. To our knowledge, this module with 312 fibre ports is the highest-capacity WSS demonstrated so far. The module can be flexibly reconfigured into different switches and port counts for advanced reconfigurable optical add/drop multiplexer (ROADM) applications. [ABSTRACT FROM AUTHOR]

Two nematic liquid crystal mixtures with high birefringence, modest dielectric anisotropy, relatively low viscosity, and wide nematic range (‐40°C ~105°C) are developed and their physical properties evaluated. When used in reflective LCoS panels, the average response time is 2.37 ms 2π phase modulation and ~1ms for amplitude modulation. Potential applications for AR and head‐up displays are emphasized. [ABSTRACT FROM AUTHOR]

This work demonstrates that wavefront encoding technique can be used reduce the peak transient crosstalk by >10 dB in holographic optical switches based on the liquid crystal on silicon (LCOS) technology, when compared with switches based on the conventional Fourier transform optical setup. At the same time, this technique also reduces the switching time, without any modifications needed to either the LCOS device or its driving circuits. [ABSTRACT FROM AUTHOR]

This paper proposes a ripple injection method in a two-stage intermediate bus architecture to overcome the incremental negative-impedance effect in the intermediate bus converter (IBC) induced by the constant power load, which is essentially a tightly regulated point of load (PoL) converter. The proposed method uses the voltage ripple of the intermediate bus in the feedback path for the closed-loop PoL converter while operating the IBC in open loop. The small-signal model is derived and verified using SIMPLIS simulation. The voltage ripple is shown to carry the inductor current information of the PoL converter. Thus, the proposed scheme is expected to retain the superior line regulation of current mode control for the PoL converter even without sensing the inductor current. Load current feed forward can improve the transient response for the PoL converter. Moreover, the load current information is also used to generate the appropriate duty ratio for the IBC during transient recovery. A simple PI controller is used for the PoL converter, which reduces the design complexity using the proposed control scheme. A hardware prototype is made, and the superior performance using the proposed control scheme is experimentally verified. [ABSTRACT FROM AUTHOR]

An $8\times \,\,16$ wavelength selective switch (WSS) with full contentionless switching is proposed and experimentally demonstrated. Utilizing two chips of liquid crystal on silicon, the optical wavelengths can be switched, attenuated, or blocked among 8 input ports and 16 output ports. The maximum insertion loss is less than 14 dB; the bandwidth tuning range is from 50 to 5000 GHz. The attenuation range is from 0 to 15 dB, and the optical blocking value is greater than 27 dB. Compared with the previous reports, the $8\times16$ WSS proposed in this letter is a truly contentionless WSS device with the highest number of input and output ports. [ABSTRACT FROM AUTHOR]

This paper reviews the recent developments in microwave photonic devices based on liquid crystal on silicon (LCOS) technology. The operation principle, functions and important specifications of an LCOS based optical processor are described. Three microwave photonic devices, which are microwave photonic notch filters, phase shifters and couplers, reported in the past five years are focused on in this paper. In addition, a new multi-function signal processing structure based on amplitude and phase control functions in conjunction with a power splitting function in a commercial LCOS based optical processor is presented. It has the ability to realize multiple time -shifting operations and multiple frequency-independent phase shifting operations at the same time and control multiple RF signal amplitudes, in a single unit. The results for the new multi-function microwave photonic signal processor demonstrate multiple tunable true time delay and phase shifting operations with less than 3 dB amplitude variation over a very wide frequency range of 10 to 40 GHz. [ABSTRACT FROM AUTHOR]

Coded aperture imaging systems have recently shown great success in recovering scene depth and extending the depth-of-field. Tremendous efforts have been focused on designing good coded patterns. The ideal pattern, however, would have to serve two conflicting purposes: 1) it should be broadband to ensure robust deconvolution and 2) it should have sufficient zero-crossings for a high depth discrepancy. This paper presents a simple but effective scene-adaptive coded aperture solution to bridge this gap. We observe that natural scenes often exhibit a dominant edge direction that can be caused by structure, texture, shading, etc. We therefore apply depth-discriminative codes along the dominant direction and broadband codes along its orthogonal direction. To physically implement this scheme, we adopt a two-shot scheme. Firstly, we capture a scene image with a pinhole aperture and analyze image content to determine the dominant direction. Secondly, we apply the proposed coding scheme using the programmable Liquid Crystal on Silicon (LCoS). Experiments on a broad range of synthetic and real scenes show that our technique is able to combine advantages of the state-of-the-art patterns for recovering better quality depth map and all-focus images. [ABSTRACT FROM AUTHOR]

Highlights • A LCOS-based 1 × 25 wavelength selective switch has been demonstrated experimentally. • Any wavelength channel can be selected and switched into any of 25 output ports independently. • The output channel passband and spacing can be adjusted flexibly through uploading a hologram on the LCOS chip. • The insertion loss for polarized beam ranges from 5.4 to 7.5 dB for 1–20 output ports and increases up to 9.6 dB at side ports for 100 GHz spaced ITU-T channels over the C-band. Abstract Wavelength-selective-switching based reconfigurable optical add-drop multiplexers are the essential components of current and next generation dynamic optical networks. A proof-of-concept 1 × 25 wavelength selective switch is demonstrated experimentally based on liquid crystal on silicon (LCOS) technology and 2- f optical system. Each of the input C-band wavelength channel can be independently selected and switched into arbitrary output ports. The channel passband and channel spacing can be adjusted flexibly by applying holograms onto an LCOS chip. The insertion loss for polarized beam ranges from 5.4 to 7.5 dB for 1–20 output ports and increases up to 9.6 dB at side ports for 100 GHz spaced ITU-T channels over the C-band. The general channel crosstalk is below −20 dB. The minimum resolution of center frequency for each channel is 5 GHz (0.04 nm). The performance can be further improved by using an LCOS chip with smaller pixel pitch, higher-quality optical components and accurate alignment of the fiber-lenslet array. [ABSTRACT FROM AUTHOR]

A liquid crystal on silicon (LCOS) device exhibiting high diffraction efficiency at a large deflection angle is demonstrated. An LC mixture with a large birefringence ($\Delta \text{n}\,\,=0.25$ at $\lambda =1550$ nm) and a large dielectric constant ($\Delta \varepsilon = 10.4$) is developed to obtain the high-phase retardation, more than $4\pi $ , at 1550 nm within a relatively low operation voltage of 5.5 V on LCOS. When compared with the conventional modulation method of $2\pi $ phase retardation, both grating period and phase retardation are doubled in $4\pi $ modulo modulation. Using the high-phase retardation modulation method, the LCOS may achieve high diffraction efficiency more than 56.6% at 4.5° deflection angle of C-band wavelength with an optimized phase retardation profile. The high diffraction efficiency phase modulator shows the great potential application of beam steering for the wavelength selective switch and the holographic display. [ABSTRACT FROM AUTHOR]

Highlights • We proposed an experimental method to calibrate LCoS displays. • We provided a self-calibrating technique based on diffractive lenses schemes. This means the used DOEs are self-generated by the LCoS to be studied. • LCoS phase-voltage look-up table, as well as the surface profile, are experimentally obtained with the same (and compact) optical arrangement. • As we are dealing with a self-calibrating approach, the technique allows to calibrate the LCoS without the necessity of external optical set-ups. Abstract An experimental method to calibrate Liquid Crystal on Silicon (LCoS) displays by self-generating lens configurations on the studied device is proposed in this paper. On the one hand, a split-lens is displayed in the LCoS to self-generate an interference pattern from which the phase-voltage curve of the modulator is calculated. On the other hand, a microlens array is displayed on the LCoS, within a same experimental set-up, to implement a Shack-Hartmann (S-H) wavefront sensor, from which the display surface profile is retrieved. Specifically, by means of a feasible set-up, the proposed method allows measuring the deviation from flatness of the LCoS displays as well as to determine the phase-voltage response of phase-only SLMs. Experimental results demonstrate a linear tendency phase-voltage curve that ranges from 0 rad up to ∼6.28 rad, for the used light wavelength. Moreover, by extracting the LCoS phase distribution measured with the S-H configuration, the LCoS surface inhomogeneity is corrected by 95%. [ABSTRACT FROM AUTHOR]

This paper presents a fully integrated system-on-chip wireless transmitter that has no need for an external quartz crystal frequency reference. Instead, a nontrimmable $LC$ oscillator (LCO) is implemented, operating at a fixed frequency of roughly 3.2 GHz. This LCO serves as the accurate frequency reference of the transmitter and is used to derive a frequency in the sub-GHz range for wireless applications via a fractional phase-locked loop. The digital functionality required for the frequency generation and thus for the wireless operation is performed by an 8-b microcontroller. The calibration data as well as the application specific firmware are stored in an integrated EEPROM. An initial frequency accuracy of ±52 ppm over a temperature of −20 °C to 85 °C is achieved using only two temperature insertions for the calibration. The device covers a continuous frequency range of 10–960 MHz and provides an ASK and GFSK operation. A low harmonic power amplifier was implemented to overcome design issues due to injection modulation effects. The chip is implemented in a 130 nm standard CMOS process and constitutes a new approach for a fully integrated wireless sub-GHz transmitter that is competitive to state-of-the-art quartz crystal-based transmitters as well as to already existing crystal-less architectures. [ABSTRACT FROM PUBLISHER]

The electrical fringing field effect between neighboring pixels of the LCOS chip will result in a parasitic grating and the crosstalk among the ports of the WSS（Wavelength Selective Switch）module.A simplified 2foptical model was established and the relationship between the electrical fringing field effect and the performances of the WSS module was analyzed based on Fourier optics.The result shows that,with the increase of the diffraction angle of the LCOS grating,the crosstalk among the outputs of the WSS module increase.Reducing the space between the outputs or increasing the focal length of the lens can reduce the crosstalk,resulting in the more the number of outputs in the WSS module.The results presented in this paper are important for the parameter design and optimization of WSS module.

This paper shows a synchronization technique of power converters based on a limit cycle oscillator (LCO) and a frequency-locked loop (FLL), which makes the system frequency adaptive. The proposed technique LCO-FLL offers a high degree of immunity and robustness against swells, sags, harmonics, and phase-frequency shift. Furthermore, the LCO-FLL has the advantage of performing the synchrony with the grid from any initial condition set for LCO, ensuring an acceptable transient onto the synchronization process. Other advantages of the proposed scheme are that it does not require a phase-locked loop or trigonometric functions and it gives useful information to estimate the positive- and negative-sequence components in a three-phase system with a highly polluted grid scenario. In this paper, a local stability analysis of the LCO-FLL is presented. The behavior and performance of the proposed technique are compared with synchronization techniques by means of experimental results. Furthermore, a three-phase application of the synchronization technique is evaluated experimentally. [ABSTRACT FROM PUBLISHER]

This paper presents an analog-assisted (AA) output-capacitor-free digital low-dropout (D-LDO) regulator with tri-loop control. For responding to instant load transients, the proposed high-pass AA loop momentarily adjusts the unit current of the power switch array, and significantly reduces the voltage spikes. In the proposed D-LDO, the overall 512 output current steps are divided into three sub-sections controlled by coarse/fine loops with carry-in/out operations. Therefore, the required shift register (SR) length is reduced, and a 9-bit output current resolution is realized by using only 28-SR bits. Besides, the coarse-tuning loop helps to reduce the recovery time, while the fine-tuning loop improves the output accuracy. To eliminate the limit cycle oscillation and reduce the quiescent current, a freeze mode is added after the fine-tuning operation. To reduce the output glitches and the recovery time, a nonlinear coarse word control is designed for the carry-in/out operations. The D-LDO is fabricated in a 65-nm general purpose CMOS process. A maximum voltage undershoot/overshoot of 105 mV is measured with a 10-mA/1-ns load step and a total capacitor of only 100 pF. Thus, the resulting figure-of-merit is 0.23 ps. [ABSTRACT FROM AUTHOR]

We demonstrate a simple illumination system based on a digital mirror device which allows for fine control over the power and pattern of illumination. We apply this to localization microscopy (LM), specifically stochastic optical reconstruction microscopy (STORM). Using this targeted STORM, we were able to image a selected area of a labelled cell without causing photo-damage to the surrounding areas of the cell. [ABSTRACT FROM AUTHOR]