scholarly journals Graphene-Based Spatial Light Modulator Using Metal Hot Spots

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3082 ◽  
Author(s):  
Zhanshan Sun ◽  
Yuejun Zheng ◽  
Yunqi Fu
Keyword(s):  
Electric Field ◽  
Hot Spots ◽  
Near Infrared ◽  
Modulation Depth ◽  
Field Enhancement ◽  
Spatial Light Modulators ◽  
Light Modulator ◽  
Light Modulators ◽  
High Modulation ◽  
Doped Graphene

Here, we report a graphene-based electric field enhancement structure achieved by several adjacent metal nanoribbons which form the hot spots of the electric field and thus promote the absorption of the single layered graphene below the hot spots. Based on the tunability of the graphene’s Fermi level, the absorption rate can be modulated from near 100% to 35% under low electrostatic gating, leading to a 20 dB modulation depth of reflectance. Compared with the existing near infrared spatial light modulators such as optical cavities integrated with graphene and other structures utilizing patterned or highly doped graphene, our design has the advantages of strong optical field enhancement, low power dissipation and high modulation depth. The proposed electro-optic modulator has a promising potential for developing optical communication and exploiting big data interaction systems.

scholarly journals Programmable Supercontinuum Laser Spectrum Generator Based on a Liquid-Crystal on Silicon Spatial Light Modulator

2021 ◽  
Vol 9 ◽  
Author(s):  
Pascuala García-Martínez ◽  
Ignacio Moreno ◽  
María del Mar Sánchez-López ◽  
Jordi Gomis ◽  
Pedro Martínez ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Optical System ◽  
Near Infrared ◽  
Single Mode ◽  
Laser Source ◽  
Spatial Light Modulators ◽  
Light Spectrum ◽  
Light Modulator ◽  
Light Modulators ◽  
Liquid Crystal On Silicon

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.

Realistic FDTD Simulations of Plasmonic Properties on Ag Columnar Thin Films as SERS Biosensor

NANO ◽  
2016 ◽  
Vol 11 (10) ◽  
pp. 1650113
Author(s):  
Yan-Juan Liao ◽  
Jing-Nan Huang ◽  
Jia-Yang Guo ◽  
Shao-Ji Jiang
Keyword(s):  
Thin Films ◽  
Electric Field ◽  
Hot Spots ◽  
Near Infrared ◽  
Structural Characteristics ◽  
Field Enhancement ◽  
Infrared Range ◽  
Electric Field Enhancement ◽  
Sem Images ◽  
Sculptured Thin Films

Noble metal sculptured thin films are of great interest during last decade as excellent surface-enhanced Raman scattering (SERS) substrates due to remarkable plasmonic properties in the visible and near-infrared range. In this work, Ag columnar thin films (Ag-CTFs) have been prepared by the glancing angle deposition technique. Finite-difference time-domain simulations has been utilized to study plasmonic properties of Ag-CTFs with a more accurate model based on binary scanning electron microscope (SEM) images by taking account of the shape irregularities, size distributions and random arrangement. The calculated absorption spectra based on the model of binarized SEM images show the best agreement with the measured spectra compared with models of periodic array with a regular shape. The near-field plasmonic properties are simulated based on the verified model. The distributions of electric field enhancement and hot spots are confirmed to be spectral and polarization dependent. There are multiple resonance peaks from visible to near-infrared and multiple eigenmodes coexist at the same wavelength and electric field enhancement are mainly excited by the polarized light vertical to the gap orientation. The electric field enhancement is found to distribute unevenly in the films with surface-localized feature. The equations to calculate the simulation SERS enhancement factor (EF) and total number of hot spots (tHN) are modified according to the above discussions. The experimental SERS EFs are on the order of 107–108, which indicates the high sensitivity of the films and the simulation SERS EFs and tHNs show good agreement with the experimental EFs. It is found that the SERS performance of Ag-CTFs is decided by both the cross-section structural characteristics and film thickness, which affect the electric filed enhancement and number of adsorbed molecules, respectively. Our work could be helpful in understanding the SERS mechanism and useful to the optimization of metal sculptured thin films for designing SERS biosensor.

scholarly journals Diffraction Efficiency Characteristics for MEMS-Based Phase-Only Spatial Light Modulator with Nonlinear Phase Distribution

Photonics ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 62
Author(s):  
Remington S. Ketchum ◽  
Pierre-Alexandre Blanche
Keyword(s):  
Diffraction Efficiency ◽  
High Speed ◽  
Phase Distribution ◽  
Complex Structure ◽  
Spatial Light Modulators ◽  
Light Modulator ◽  
Micro Electro Mechanical Systems ◽  
Light Modulators ◽  
Nonlinear Phase ◽  
Liquid Crystal On Silicon

Micro-electro mechanical systems (MEMS)-based phase-only spatial light modulators (PLMs) have the potential to overcome the limited speed of liquid crystal on silicon (LCoS) spatial light modulators (SLMs) and operate at speeds faster than 10 kHz. This expands the practicality of PLMs to several applications, including communications, sensing, and high-speed displays. The complex structure and fabrication requirements for large, 2D MEMS arrays with vertical actuation have kept MEMS-based PLMs out of the market in favor of LCoS SLMs. Recently, Texas Instruments has adapted its existing DMD technology for fabricating MEMS-based PLMs. Here, we characterize the diffraction efficiency for one of these PLMs and examine the effect of a nonlinear distribution of addressable phase states across a range of wavelengths and illumination angles.

scholarly journals Phase-only transmissive spatial light modulator based on tunable dielectric metasurface

Science ◽  
2019 ◽  
Vol 364 (6445) ◽  
pp. 1087-1090 ◽  
Author(s):  
Shi-Qiang Li ◽  
Xuewu Xu ◽  
Rasna Maruthiyodan Veetil ◽  
Vytautas Valuckas ◽  
Ramón Paniagua-Domínguez ◽  
...  
Keyword(s):  
High Resolution ◽  
Spatial Light Modulator ◽  
Deflection Angle ◽  
Beam Steering ◽  
Beam Deflection ◽  
Spatial Light Modulators ◽  
Light Modulator ◽  
Steering Angle ◽  
Holographic Display ◽  
Light Modulators

Rapidly developing augmented reality, solid-state light detection and ranging (LIDAR), and holographic display technologies require spatial light modulators (SLMs) with high resolution and viewing angle to satisfy increasing customer demands. Performance of currently available SLMs is limited by their large pixel sizes on the order of several micrometers. Here, we propose a concept of tunable dielectric metasurfaces modulated by liquid crystal, which can provide abrupt phase change, thus enabling pixel-size miniaturization. We present a metasurface-based transmissive SLM, configured to generate active beam steering with >35% efficiency and a large beam deflection angle of 11°. The high resolution and steering angle obtained provide opportunities to develop the next generation of LIDAR and display technologies.

scholarly journals Progress in Phase Calibration for Liquid Crystal Spatial Light Modulators

2019 ◽  
Vol 9 (10) ◽  
pp. 2012 ◽  
Author(s):  
Rujia Li ◽  
Liangcai Cao
Keyword(s):  
Optical Tweezers ◽  
Phase Modulation ◽  
Spatial Light Modulators ◽  
Light Modulator ◽  
Holographic Display ◽  
Light Modulators ◽  
Interferometric Phase ◽  
Calibration Methods ◽  
Phase Calibration ◽  
Potential Methods

Phase-only Spatial Light Modulator (SLM) is one of the most widely used devices for phase modulation. It has been successfully applied in the field with requirements of precision phase modulation such as holographic display, optical tweezers, lithography, etc. However, due to the limitations in the manufacturing process, the grayscale-phase response could be different for every single SLM device, even varying on sections of an SLM panel. A diverse array of calibration methods have been proposed and could be sorted into two categories: the interferometric phase calibration methods and the diffractive phase calibration methods. The principles of phase-only SLM are introduced. The main phase calibration methods are discussed and reviewed. The advantages of these methods are analyzed and compared. The potential methods for different applications are suggested.

Response Time of a-Si:H Photosensors in Optically Addressed Spatial Light Modulators

1991 ◽  
Vol 219 ◽  
Author(s):  
Garret Moddel ◽  
Pierre R. Barbier
Keyword(s):  
Liquid Crystal ◽  
Response Time ◽  
Spatial Light Modulator ◽  
Reverse Bias ◽  
Forward Bias ◽  
Spatial Light Modulators ◽  
Photocurrent Response ◽  
Light Modulator ◽  
Double Injection ◽  
Light Modulators

ABSTRACTA successful application for a-Si:H is as the photosensor in a liquid crystal optically addressed spatial light modulator (OASLM). We analyze the response time of an a-Si:H p-i-n photodiode in a “pseudo-OALSM,” in which the liquid crystal is replaced by an equivalent capacitor, under both forward and reverse bias. Under reverse bias the two important effects are the photocurrent response time, and residual trapped charge. Under forward bias the mechanism shifts from double injection regimes to ohmic transport as a function of voltage. We relate these characteristics to the operation of an OASLM.

scholarly journals Dielectric-loading approach for extra electric field enhancement and spatially transferring plasmonic hot-spots

2020 ◽  
Vol 32 (3) ◽  
pp. 035205
Author(s):  
Mingjie Wan ◽  
Jingyu Wu ◽  
Jun Liu ◽  
Zhuo Chen ◽  
Ping Gu ◽  
...  
Keyword(s):  
Electric Field ◽  
Hot Spots ◽  
Field Enhancement ◽  
Electric Field Enhancement ◽  
Dielectric Loading

scholarly journals High Fidelity Spatial Light Modulator Configuration for Photo-Stimulation

2021 ◽  
Vol 9 ◽  
Author(s):  
Samira Aghayee ◽  
Mitchell Weikert ◽  
Phillip Alvarez ◽  
Gabriel A. Frank ◽  
Wolfgang Losert
Keyword(s):  
Spatial Light Modulator ◽  
Signal To Noise Ratio ◽  
Spatial Light Modulators ◽  
High Signal ◽  
High Fidelity ◽  
Light Modulator ◽  
Fourier Plane ◽  
Two Photon ◽  
Light Modulators ◽  
The Brain

For their capacity to shape optical wavefronts in real time into any desired illumination pattern, phase-only Spatial Light Modulators (SLM) have proven to be powerful tools for optical trapping and micromanipulation applications. SLMs are also becoming increasingly utilized in selective photo-stimulation of groups of neurons in the brain. However, conventional SLM based wavefront modulation introduces artifacts that are particularly detrimental for photo-stimulation applications. The primary issue is the unmodulated light that travels along the 0th order of diffraction. This portion of light is commonly blocked at the center of the object plane, which prevents photo-stimulation in the blocked region. We demonstrate a virtual lens configuration that moves the 1st order diffraction with the desired illumination pattern into the Fourier plane of the 0th order light. This virtual lens setup makes the whole field of view accessible for photo-stimulation and eliminates the need for removing the 0th order light in two-photon applications. Furthermore, in an example application to reconstruct a pattern consisting of an array of points, the virtual lens configuration increases the uniformity of the intensities these points. Moreover, diffraction-induced artifacts are also significantly reduced within the target plane. Therefore, our proposed high fidelity configuration yields target points with high signal to noise ratio.

scholarly journals Focal beam structuring by triple mixing of optical vortex lattices

2021 ◽  
Vol 54 (1) ◽  
Author(s):  
Lyubomir Stoyanov ◽  
Georgi Maleshkov ◽  
Ivan Stefanov ◽  
Gerhard G. Paulus ◽  
Alexander Dreischuh
Keyword(s):  
Spatial Light Modulator ◽  
Optical Vortex ◽  
Spatial Light Modulators ◽  
Reliable Control ◽  
Control Parameters ◽  
Light Modulator ◽  
Vortex Lattices ◽  
On Demand ◽  
Ordered Arrays ◽  
Light Modulators

AbstractOn-demand generation and reshaping of arrays of focused laser beams is highly desired in many areas of science and technology. In this work, we present a versatile approach for laser beam structuring in the focal plane of a lens by triple mixing of square and/or hexagonal optical vortex lattices (OVLs). In the artificial far field the input Gaussian beam is reshaped into ordered arrays of bright beams with flat phase profiles. This is remarkable, since the bright focal peaks are surrounded by hundreds of OVs with their dark cores and two-dimensional phase dislocations. Numerical simulations and experimental evidences for this are shown, including a broad discussion of some of the possible scenarios for such mixing: triple mixing of square-shaped OVLs, triple mixing of hexagonal OVLs, as well as the two combined cases of mixing square-hexagonal-hexagonal and square-square-hexagonal OVLs. The particular ordering of the input phase distributions of the OV lattices on the used spatial light modulators is found to affect the orientation of the structures ruled by the hexagonal OVL. Reliable control parameters for the creation of the desired focal beam structures are the respective lattice node spacings. The presented approach is flexible, easily realizable by using a single spatial light modulator, and thus accessible in many laboratories.

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