Compact optical correlator based on one phase-only spatial light modulator

Xu, Ziqiang; Bai, Jian; Hou, Changlun; Yang, Guoguang

doi:10.1364/ol.36.001383

Cited by 20 publications

(10 citation statements)

References 10 publications

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“…LCoS has amplitude-modulating type (mainly for video and image projections) and phase-only modulating type. The latter has more extensive applications in optical correlators, 11 diffractive optical components, 12 wavelength selective switches, 13 and real-time holography. 14 The holographic display reproduces the wavefront of the object and uses LCoS to reconstruct the natural light.…”

Section: ■ Introductionmentioning

confidence: 99%

Accurate Phase Modulation Scheme in a Micropixel Liquid Crystal on Silicon with Multiple Polymer Walls

Chu

Guo

Zhang

et al. 2023

ACS Appl. Opt. Mater.

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In the micropixel liquid crystal on silicon (LCoS), the fringe electric field seriously affects the phase modulation accuracy of the adjacent pixels. In this paper, we propose an accurate phase modulation scheme in micropixel LCoS with multiple polymer walls. The multiple polymer walls are fabricated between aluminum (Al) electrodes to block the crosstalk of the fringe electric field between adjacent pixel arrays and reduce the change of liquid crystal (LC) molecular inclination angle. Therefore, the phase can be accurately controlled by the driving voltage. The change in LC molecular inclination angle in the edge of the driving Al electrode is simulated, and the improvement effect of the multiple polymer walls on light leakage is also analyzed. The simulation results show that the change in the LC molecular inclination angle and light leakage in the edge of the driving Al electrodes can be ignored. In addition, we also fabricate the multiple polymer walls in the LC cell, which are made of a photoresist on the oriented glass substrate. The experimental results indicate that the LC cell with multiple polymer walls shows good bright and dark states, which proves that the phase can be accurately adjusted.

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Section: ■ Introductionmentioning

confidence: 99%

Accurate Phase Modulation Scheme in a Micropixel Liquid Crystal on Silicon with Multiple Polymer Walls

Chu

Guo

Zhang

et al. 2023

ACS Appl. Opt. Mater.

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“…Unlike amplitude-modulating LCOS devices (mainly for video and image projections), phase-only modulating LCOS devices have a wide range of applications based on the spatial modulation of coherent lights, [14][15][16] including real-time holography, 17 optical correlators, 18 wavelength selective switches, 19,20 reconfigurable optical add-drop multiplexers [20][21][22] and diffractive optical components. [23][24][25] The first attempt to drive an LC pixel array from a single crystal silicon active backplane was proposed by Ernstoff et al 26 in the early 1970s.…”

Section: Brief Introduction To Lcos Devicesmentioning

confidence: 99%

Fundamentals of phase-only liquid crystal on silicon (LCOS) devices

2014

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This paper describes the fundamentals of phase-only liquid crystal on silicon (LCOS) technology, which have not been previously discussed in detail. This technology is widely utilized in high efficiency applications for real-time holography and diffractive optics. The paper begins with a brief introduction on the developmental trajectory of phase-only LCOS technology, followed by the correct selection of liquid crystal (LC) materials and corresponding electro-optic effects in such devices. Attention is focused on the essential requirements of the physical aspects of the LC layer as well as the indispensable parameters for the response time of the device. Furthermore, the basic functionalities embedded in the complementary metal oxide semiconductor (CMOS) silicon backplane for phase-only LCOS devices are illustrated, including two typical addressing schemes. Finally, the application of phase-only LCOS devices in real-time holography will be introduced in association with the use of cutting-edge computer-generated holograms. The architecture of LCOS devices is similar to conventional LC devices except that a silicon backplane constitutes one of the substrates (Figure 1). The silicon CMOS backplane consists of the electronic circuitry that is buried underneath pixel arrays to provide a high 'fill factor'. The pixels are aluminum mirrors deposited on the surface of the silicon backplane. The incident light is transmitted through the LC layer with almost zero absorption. The integration of high-performance driving circuitry allows the applied voltage to be changed on each pixel, thereby controlling the phase retardation of the incident wavefront across the device. Currently, there are two types of light modulation using LCOS devices, amplitude modulation and phase modulation. In the former case, the amplitude of the light signal is modulated 6,7 by varying the linear polarzation direction of the incident light passing through a linear polarizer, the same principle used in a standard LC television. In the latter case, the phase delay is accomplished by electrically adjusting the optical refractive index along the light path, which is possible because of the non-zero birefringence of the LC materials in use but should be carefully characterized. [8][9][10][11][12][13] In a phase-only LCOS SLM modulator, no light absorption by polarizers or other light-absorbing components will occur, such that the maximum light efficiency can be expected.Currently, most of the conventional LC devices are not able to efficiently modulate the phase of an incident wavefront. For instance, the LC device structure using thin film transistors is not suitable for phase modulation because an appropriate electro-optic effect has not been used (see the section on 'Twisted nematic (TN) configuration' and the section on 'VAN configuration' for details). Moreover, the pixels of this type of device are too large to provide acceptably large diffraction angles. In addition, the pixel circuitry and connection tracks are in the light path such that the ...

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“…The first types of device reads the images stored in the hard disk drive, for example, and is flexible in that it can be applied to scene matching 2,[6][7][8] that is suitable for a small capacity database. However, its data transfer rate is limited by the frame rate of the SLM.…”

Section: Introductionmentioning

confidence: 99%

High-speed optical correlator with coaxial holographic system

Ikeda¹,

Watanabe²

2015

Jpn. J. Appl. Phys.

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A high-speed volume holographic optical correlator is developed, which takes advantage of a coaxial holographic system. We have realized this high-speed correlator using an optimal design of the signal pattern, which improves the shift multiplex recording shift pitch. The speed of this correlator was further improved by increasing the number of pixels in the spatial light modulator and using a high speed rotating actuator. This correlation system successfully achieved an equal error rate of 0% by performing optical correlation over 900 times. It also achieved optical correlation experiment, at a shift pitch of 2.45 µm and a disk rotation speed of 900 rpm. In terms of optical correlation calculation speed, it yielded a peak interval of 542 ns, which corresponds to 1.846 × 106 frames per second.

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Compact optical correlator based on one phase-only spatial light modulator

Cited by 20 publications

References 10 publications

Accurate Phase Modulation Scheme in a Micropixel Liquid Crystal on Silicon with Multiple Polymer Walls

Accurate Phase Modulation Scheme in a Micropixel Liquid Crystal on Silicon with Multiple Polymer Walls

Fundamentals of phase-only liquid crystal on silicon (LCOS) devices

High-speed optical correlator with coaxial holographic system

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