Selection of Voltage and Spectral Range in Liquid Crystal Gating

2010 ◽  
Vol 428-429 ◽  
pp. 406-410
Author(s):  
Han Cheng Liu ◽  
Hua Wa Yu ◽  
Xiang An Yan ◽  
Jun Fang Wu
Keyword(s):  
Liquid Crystal ◽  
Wavelength Range ◽  
Spectral Range ◽  
Incident Light ◽  
Extinction Ratio ◽  
Low Light ◽  
Incident Wavelength ◽  
Reflected Light ◽  
Point Control ◽  
Selection Of

Liquid crystal device (LCD) used as spatial gating apparatus has a lot of new using at low light detecting, imaging spectrum and so on. Since LCD's lattice characteristic, it can come true point gating, local field gating and whole surface gating. It can carry out point-by-point control and feedback of imaging cooperating with CCD detector. Some characteristics of we used LCD, LCX023CMT (SONY), have been detected in order to use conveniently, those include spectra transmittance and which’s changing with gating voltage. The results show that when incident wavelength more than 650nm, this LCD couldn't be used as spatial gating because of polaroid's extinction ratio becoming worse; LCD can modulate the incident light from 400 to 650nm, and the modulates of wavelength range, extent and linearity were related to the modulate voltage clearly. The results indicate that LCD modulates the incident light better and better at voltage more than 2.5V for 550nm; the action modulated become linear with voltage approximately; the modulate extent goes to saturation at voltage more than 5V, and the spectral range modulated is steady in 400-650nm. At voltage more than 5V, transmittance of spectrum is a horizontal beeline almost with incident wavelength range from 400 to 650nm. This indicates that transmittance of spectrum in this range is same, and liquid crystal has none selectivity in colored light. As a result, there is no chromatism between transmitted and incident light. However, because that there is lower transmittance, the reflected light can be used which can ensure not only effective using ratio of light, but also the consistency between reflected and incident light.

scholarly journals A Simple Simulation of Surface Plasmon Resonance in The Kretschmann Configuration Using Google Sheets

2020 ◽  
Vol 16 (2) ◽  
pp. 83-91
Author(s):  
N. K. Quang ◽  
N. P. Q. Anh ◽  
H. C. Hieu
Keyword(s):  
Surface Plasmon Resonance ◽  
Surface Plasmon ◽  
Plasmon Resonance ◽  
Incident Light ◽  
Layer System ◽  
Incident Wavelength ◽  
Web Based ◽  
Kretschmann Configuration ◽  
Reflected Light ◽  
Simple Simulation

This article describes a simple numerical simulation of three-layer surface plasmon resonance (SPR) in the Kretschmann configuration. The calculation was performed in Google Sheets, a web-based spreadsheet environment that functions similarly to Microsoft Excel where it is easily accessible for students via the internet. Specifically, Fresnel’s equations were utilized to calculate the intensity of the reflected light for the p-polarized incident light on a three-layer system. The complex functions were utilized to plot the SPR curves. We examined the change of the resonance angle by the influence of the incident wavelength. The simulation was also performed for different thicknesses of the gold film layer. To demonstrate the sensitivity, we obtained the SPR curves with the variation of the refractive index in the sensitive medium. The SPR accuracy was analysed by comparing our obtained result with the published work. It is intended to incorporate into undergraduate instrumental analysis courses.

Results of Spatial Structure of Atmosphere Radiation in a Spectral Range (1.5–2) µm Research

2018 ◽  
pp. 7-13
Author(s):  
Anton M. Mishchenko ◽  
Sergei S. Rachkovsky ◽  
Vladimir A. Smolin ◽  
Igor V . Yakimenko
Keyword(s):  
Spatial Structure ◽  
Unmanned Aerial Vehicle ◽  
Wavelength Range ◽  
Spectral Range ◽  
Near Ir ◽  
Optoelectronic Systems ◽  
Aerial Vehicle

Results of experimental studying radiation spatial structure of atmosphere background nonuniformities and of an unmanned aerial vehicle being the detection object are presented. The question on a possibility of its detection using optoelectronic systems against the background of a cloudy field in the near IR wavelength range is also considered.

Electrically-Controllable Liquid Crystal Polarizing Filter for Eliminating Reflected Light

1998 ◽  
Vol 5 (2) ◽  
pp. 93-98 ◽  
Author(s):  
Hideo Fujikake ◽  
Kuniharu Takizawa ◽  
Tahito Aida ◽  
Hiroshi Kikuchi ◽  
Takanori Fujii ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Reflected Light

scholarly journals Design of Tunable Holographic Liquid Crystalline Diffraction Gratings

Sensors ◽  
2020 ◽  
Vol 20 (23) ◽  
pp. 6789
Author(s):  
Katarzyna A. Rutkowska ◽  
Anna Kozanecka-Szmigiel
Keyword(s):  
Liquid Crystal ◽  
Communication Networks ◽  
Optical Communication ◽  
Liquid Crystalline ◽  
Incident Light ◽  
Diffraction Gratings ◽  
Lagrange Equations ◽  
Experimental Conditions ◽  
Molecular Distribution ◽  
Polarization Gratings

Tunable diffraction gratings and phase filters are important functional devices in optical communication and sensing systems. Polarization gratings, in particular, capable of redirecting an incident light beam completely into the first diffraction orders may be successfully fabricated in liquid crystalline cells assembled from substrates coated with uniform transparent electrodes and orienting layers that force a specific molecular distribution. In this work, the diffraction properties of liquid crystal (LC) cells characterized by a continually rotating cycloidal director pattern at the cell substrates and in the bulk, are studied theoretically by solving a relevant set of the Euler-Lagrange equations. The electric tunability of the gratings is analyzed by estimating the changes in liquid crystalline molecular distribution and thus in effective birefringence, as a function of external voltage. To the best of our knowledge, such detailed numerical calculations have not been presented so far for liquid crystal polarization gratings showing a cycloidal director pattern. Our theoretical predictions may be easily achieved in experimental conditions when exploiting, for example, photo-orienting material, to induce a permanent LC alignment with high spatial resolution. The proposed design may be for example, used as a tunable passband filter with adjustable bandwidths, thus allowing for potential applications in optical spectroscopy, optical communication networks, remote sensing and beyond.

scholarly journals Electrical tuning of the polarization state of light using graphene-integrated anisotropic metasurfaces

2017 ◽  
Vol 375 (2090) ◽  
pp. 20160061 ◽  
Author(s):  
Shourya Dutta-Gupta ◽  
Nima Dabidian ◽  
Iskandar Kholmanov ◽  
Mikhail A. Belkin ◽  
Gennady Shvets
Keyword(s):  
Tilt Angle ◽  
Incident Light ◽  
Polarization State ◽  
Dynamic Control ◽  
Single Layer ◽  
Single Layer Graphene ◽  
Dynamic Polarization ◽  
Reflected Light ◽  
Electro Optic ◽  
The Way

Plasmonic metasurfaces have been employed for moulding the flow of transmitted and reflected light, thereby enabling numerous applications that benefit from their ultra-thin sub-wavelength format. Their appeal is further enhanced by the incorporation of active electro-optic elements, paving the way for dynamic control of light's properties. In this paper, we realize a dynamic polarization state generator using a graphene-integrated anisotropic metasurface (GIAM) that converts the linear polarization of the incident light into an elliptical one. This is accomplished by using an anisotropic metasurface with two principal polarization axes, one of which possesses a Fano-type resonance. A gate-controlled single-layer graphene integrated with the metasurface was employed as an electro-optic element controlling the phase and intensity of light polarized along the resonant axis of the GIAM. When the incident light is polarized at an angle to the resonant axis of the metasurface, the ellipticity of the reflected light can be dynamically controlled by the application of a gate voltage. Thus accomplished dynamic polarization control is experimentally demonstrated and characterized by measuring the Stokes polarization parameters. Large changes of the ellipticity and the tilt angle of the polarization ellipse are observed. Our measurements show that the tilt angle can be changed from positive values through zero to negative values while keeping the ellipticity constant, potentially paving the way to rapid ellipsometry and other characterization techniques requiring fast polarization shifting. This article is part of the themed issue ‘New horizons for nanophotonics’.

scholarly journals Photorelease of phosphates: Mild methods for protecting phosphate derivatives

2014 ◽  
Vol 10 ◽  
pp. 2038-2054 ◽  
Author(s):  
Sanjeewa N Senadheera ◽  
Abraham L Yousef ◽  
Richard S Givens
Keyword(s):  
Excited State ◽  
Incident Light ◽  
Protecting Group ◽  
Triplet Excited State ◽  
Ambient Conditions ◽  
Incident Wavelength ◽  
Aqueous Acetonitrile ◽  
Favorskii Rearrangement ◽  
Naphthyl Ring ◽  
Diethyl Phosphate

We have developed a new photoremovable protecting group for caging phosphates in the near UV. Diethyl 2-(4-hydroxy-1-naphthyl)-2-oxoethyl phosphate (14a) quantitatively releases diethyl phosphate upon irradiation in aq MeOH or aq MeCN at 350 nm, with quantum efficiencies ranging from 0.021 to 0.067 depending on the solvent composition. The deprotection reactions originate from the triplet excited state, are robust under ambient conditions and can be carried on to 100% conversion. Similar results were found with diethyl 2-(4-methoxy-1-naphthyl)-2-oxoethyl phosphate (14b), although it was significantly less efficient compared with 14a. A key step in the deprotection reaction in aq MeOH is considered to be a Favorskii rearrangement of the naphthyl ketone motif of 14a,b to naphthylacetate esters 25 and 26. Disruption of the ketone-naphthyl ring conjugation significantly shifts the photoproduct absorption away from the effective incident wavelength for decaging of 14, driving the reaction to completion. The Favorskii rearrangement does not occur in aqueous acetonitrile although diethyl phosphate is released. Other substitution patterns on the naphthyl or quinolin-5-yl core, such as the 2,6-naphthyl 10 or 8-benzyloxyquinolin-5-yl 24 platforms, also do not rearrange by aryl migration upon photolysis and, therefore, do not proceed to completion. The 2,6-naphthyl ketone platform instead remains intact whereas the quinolin-5-yl ketone fragments to a much more complex, highly absorbing reaction mixture that competes for the incident light.

THE APPLICATION OF A NEUTRON IDENTIFICATION CIRCUIT TO THE STUDY OF FAST-NEUTRON INTERACTIONS IN STILBENE

1963 ◽  
Vol 41 (5) ◽  
pp. 793-811 ◽  
Author(s):  
F. A. Johnson
Keyword(s):  
Space Charge ◽  
Fast Neutron ◽  
Excited States ◽  
Light Output ◽  
Particle Spectrum ◽  
Low Light ◽  
Trigger Circuit ◽  
Equivalent Electron ◽  
Selection Of ◽  
Α Particles

A neutron identification circuit is described which has a threshold corresponding to a neutron energy of about 350 kev (50–60 kev equivalent electron energy). The photomultiplier is operated under conditions of space-charge saturation. Selection of pulses due to recoil protons or heavier particles is accomplished by allowing the initial negative-going spike of the space-charge-limited pulse from the last dynode to activate a trigger circuit, the output of which is used to gate the subsequent positive portion of the dynode pulse for presentation to a simple diode discriminator. Separation of pulses due to recoil protons and to α particles is also possible to some extent.The circuit is applied to an investigation of fast-neutron interactions in stilbene. For the case of 14.85-Mev neutrons it is shown that the majority of pulses of low light-output are due to α particles produced by neutron interactions with the carbon and that structure is apparent in this α-particle spectrum. α-Particle groups due to the C12(n, α)Be9 reaction and to the breakup of C12 from its excited states at 7.656 Mev and 9.63 or 10.1 Mev are identified.

Research on reflective three-output by packaged grating under second Bragg angle

2019 ◽  
Vol 33 (25) ◽  
pp. 1950305 ◽  
Author(s):  
Wenhua Zhu ◽  
Bo Wang ◽  
Chenhao Gao ◽  
Kunhua Wen ◽  
Ziming Meng ◽  
...  
Keyword(s):  
High Efficiency ◽  
Incident Light ◽  
Polarized Light ◽  
Bragg Angle ◽  
Duty Ratio ◽  
Wave Analysis ◽  
Incident Wavelength ◽  
Rigorous Coupled Wave Analysis ◽  
Rigorous Coupled Wave ◽  
The Given

This paper designed a novel three-output reflective packaged grating. The optimized parameters such as the period and depth of the high-efficiency three-output grating with an incident wavelength of 1550 nm can be calculated by rigorous coupled-wave analysis (RCWA). According to the optimized result, the grating can diffract the incident light energy into three orders with an efficiency of nearly 33% under the premise of second Bragg angle incidence and the given duty ratio of 0.5. The diffraction efficiency of the packaged grating is improved compared to the surface-relief three-output grating under second Bragg angle incidence, especially for TE-polarized light.

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