Enhancement of diffraction efficiency for optical gratings

2000 ◽  
Vol 78 (5-6) ◽  
pp. 537-542
Author(s):  
G Z Zhang
Keyword(s):  
Light Beam ◽  
Diffraction Efficiency ◽  
Beam Energy ◽  
Incident Light ◽  
Glass Plate ◽  
Air Gap ◽  
Multiple Reflection ◽  
Input Beam ◽  
Incident Light Beam ◽  
Optical Gratings

A method to increase the diffraction efficiency for optical gratings is proposed. Using a simple glass plate sitting parallel to the top of a grating surface, one can form an air gap between the surfaces of the grating and the glass plate to reflect a grazing-incident light beam and make diffraction through multiple reflection of the beam between the grating and glass plate surfaces. As a result, this device can efficiently enhance the grating efficiency by diffracting the input beam energy into various diffraction orders. PACS Nos.: 07.60-j, 42.25Fx, 42.40Lx, 42.79Dj, 42.40Fg

Excitation of a ridge waveguide by a normally incident light beam

1995 ◽  
Vol 25 (6) ◽  
pp. 582-586 ◽  
Author(s):  
O Parriaux ◽  
V A Sychugov ◽  
A V Tishchenko
Keyword(s):  
Light Beam ◽  
Incident Light ◽  
Ridge Waveguide ◽  
Incident Light Beam

scholarly journals The polymer converter for effectively connecting polymer with silica optical fibres

2016 ◽  
Vol 24 (3) ◽  
Author(s):  
P. Pura-Pawlikowska ◽  
M. Dudek ◽  
R. Wonko ◽  
P. Marć ◽  
M. Kujawińska ◽  
...  
Keyword(s):  
Light Beam ◽  
Mechanical Characteristics ◽  
Incident Light ◽  
Optical Power ◽  
Good Alternative ◽  
Optical Fibres ◽  
Incident Light Beam ◽  
Micrometer Size ◽  
Guiding Effect ◽  
Selection Of

AbstractWe present a micrometer-size polymer converter (microbridge) for connecting polymer optical fibres with silica fibres. The procedure of preparing such microstructure is based on a process of photopolymerization. A polymer converter grows as an extension of the fibres’ cores due to a self-guiding effect of the light beam in a photopolymerizable medium. Since the polymer microbridge has refractive index greater inside than outside, such a structure works as a waveguide leading the light beam between connected optical fibres. By selection of time of light exposition to the mixture and optical power of the incident light beam, it is possible to obtain a polymer converter with very good optical and mechanical characteristics. Possibility of using polymer microbridges grown directly from the fibres’ core as coupling elements between silica and polymer fibres is a good alternative for obtaining permanent coupling of such fibres.

scholarly journals Spatial light modulators

Photoniques ◽  
2020 ◽  
pp. 59-64
Author(s):  
Aurélie Jullien
Keyword(s):  
Light Beam ◽  
Technological Development ◽  
Incident Light ◽  
Spatial Light Modulators ◽  
Incident Light Beam ◽  
Light Modulators ◽  
Spatial Dimensions ◽  
The Subject

Spatial Light Modulators (SLMs) are quasiplanar devices, allowing for the modulation of the amplitude, phase and polarization, or a combination of these parameters of an incident light beam according to the two spatial dimensions of the modulator. SLMs are employed in many different fields and are the subject of continuous technological development.

scholarly journals ERROR ANALYSIS OF THE DISPERSION-COMPENSATED WIDE-BAND POLARIZATION SAGNAC INTERFEROMETER

2020 ◽  
Vol XLIII-B1-2020 ◽  
pp. 621-625
Author(s):  
J. Zhu ◽  
K. Zong ◽  
F. Goudail ◽  
N. Zhang ◽  
X. Hou
Keyword(s):  
Diffraction Efficiency ◽  
Incident Light ◽  
Wide Band ◽  
Reconstruction Error ◽  
Optical Elements ◽  
Blazed Grating ◽  
Interference Fringes ◽  
Splitting Ratio ◽  
Imaging Polarimetry ◽  
Modulation Degree

Abstract. Imaging polarimetry can obtain two-dimensional intensity distribution information and its corresponding states of polarization from the target simultaneously. Sagnac polarization imaging interferometer is one of the typical channeled polarimetry technologies. By splitting the incident light through the triangular optical structure, the polarization information of the target is modulated into the interference fringes and can be obtained by the demodulation algorithm. The non-ideal optical elements in the system will cause reconstruction errors. This article analyses several factors that affect the measurement accuracy, including the splitting ratio of polarization beam splitter and the diffraction efficiency of the blazed grating. We derive the modified intensity formula and obtain interference patterns through numerical simulations. By calculating the modulation degree of interference fringes and reconstruction error under different non-ideal parameters, we have come to the conclusion that to meet the requirement of modulation degree > 0.5 and reconstruction error < 10%, the beam splitting ratio of the PBS should be α < 1.22. The diffraction efficiency ratio of s-polarization to p-polarization of the blazed grating should be ηs/ηp > 0.83, and the first-order diffraction efficiency should be η1 > 79%.

Quasi Two-Dimensional Evaporation and Boiling Under Reduced Pressure

2017 ◽  
Vol 25 (01) ◽  
pp. 1750003 ◽  
Author(s):  
Keita Ogawa ◽  
Yuichi Yasumoto ◽  
Mitsuhiro Matsumoto ◽  
Hidenobu Wakabayashi
Keyword(s):  
Organic Liquid ◽  
Incident Light ◽  
Thin Liquid Film ◽  
Glass Plate ◽  
Float Glass ◽  
Laminated Plates ◽  
Two Dimensional ◽  
Test Liquid ◽  
Reduced Pressure ◽  
Solvent Vapor

To study the washing mechanism of laminated plates with solvent vapor, we have experimentally investigated evaporation dynamics of liquid confined between solid plates under reduced pressure. As the test liquid, we use deionized water and several organic compounds. To visualize the fluid motion in the thin gaps, we adopt glass plates. When a test liquid is sandwiched between a normal (float) glass plate and a ground (sand-blasted) one, vertically incident light passes through the plates without much scattering; once the liquid starts to evaporate, dried rough surface of the ground glass scatters the light and we can monitor the flow pattern. Based on the transmitted light intensity, the whole plate area is categorized into three regions; completely wet, completely dry, and semi-dry one; the last one is supposed to be the state that thin liquid film spreads on the plate. In the case of water, many tiny spots of semi-dry region appear and expand at the initial stage, which is probably cavitation of dissolved gas. In organic liquid cases, evaporation seems to start from the edges of the plates. At a later stage, the semi-dry region expands with complicated branching patterns. In all cases, occasional rapid motions of liquid were observed, which correspond to two-dimensional flash boiling. We also investigated the influence of the control pressure, the surface roughness, and the plate deformation.

Indirect measurement of light beam energy

1978 ◽  
Vol 21 (5) ◽  
pp. 487-492
Author(s):  
A. S. Krest'yaninov ◽  
V. V. Mityugov
Keyword(s):  
Light Beam ◽  
Beam Energy ◽  
Indirect Measurement

scholarly journals Surface Plasmons for Probing Optical Data of Multi- Layered Thin Films

2000 ◽  
Vol 5 ◽  
pp. 105
Author(s):  
A. Rais ◽  
A. Sellai
Keyword(s):  
Surface Plasmons ◽  
Optical Constant ◽  
Incident Light ◽  
Air Gap ◽  
Optical Data ◽  
Layered System ◽  
Geometrical Parameters ◽  
Matrix Formalism ◽  
Minimization Method ◽  
Al Oxide

In this paper, we show how optical excitation of surface plasmons (SPs) can be used to obtain optical and geometrical parameters of specific layers in multi-layered thin film systems. The optimum coupling phenomenon between incoming p-polarized light and SPs appears as a minimum in the reflectance that is calculated using a standard matrix formalism. The sensitive dependence of the reflectance minimum on optical and geometrical parameters suggests that they can be determined accurately by fitting the measured attenuated total reflectance (ATR) to the matrix-calculated reflectance using the Simplex minimization method. The procedure is applied to the multi-layered system: Prism / Air gap / Al-oxide / Al / GaAs. At fixed incident light wavelength, the fitting parameters are the Al-oxide optical constant and the thickness of the air gap, Al-oxide and Al layers. Fortran codes are implemented for the reflectance calculations and the fitting procedures. The results show that the theoretical reflectance fits well the measured ATR at 633 nm wavelength. Moreover, the modeled Al-oxide optical constant at this wavelength agrees well with the literature. However, the reflectance fits are less good at 590 nm and 458 nm wavelengths and their modeled Al-oxide optical constants show a dispersion effect in disagreement with the literature. The modeled geometrical parameters are consistent with the nominal values.

scholarly journals The anatomy of the foveola reinvestigated

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4482 ◽  
Author(s):  
Alexander V. Tschulakow ◽  
Theo Oltrup ◽  
Thomas Bende ◽  
Sebastian Schmelzle ◽  
Ulrich Schraermeyer
Keyword(s):  
Light Beam ◽  
Focused Ion Beam ◽  
Light Transmission ◽  
Ion Beam ◽  
Incident Light ◽  
3D Structure ◽  
Müller Cells ◽  
Bright Spot ◽  
Muller Cells ◽  
Outer Segments

Objective In the foveola of the eye, photoreceptors and Müller cells with a unique morphology have been described, but little is known about their 3D structure and orientation. Considering that there is an angle-dependent change in the foveolar photoreceptor response for the same light beam, known as the Stiles Crawford Effect of the first kind (SCE I), which is still not fully understood, a detailed analysis of the anatomy of the foveolar cells might help to clarify this phenomenon. Methods Serial semithin and ultrathin sections, and focused ion beam (FIB) tomography were prepared from 32 foveolae from monkeys (Macaca fascicularis) and humans. Foveolae were also analyzed under the electron microscope. Serial sections and FIB analysis were then used to construct 3D models of central Müller and photoreceptor cells. In addition, we measured the transmission of collimated light under the light microscope at different angles after it had passed through human foveae from flat mounted isolated retinae. Results In monkeys, outer segments of central foveolar cones are twice as long as those from parafoveal cones and do not run completely parallel to the incident light. Unique Müller cells are present in the central foveolae (area of 200 µm in diameter) of humans and monkeys. Light entering the fovea center, which is composed only of cones and Müller cells, at an angle of 0° causes a very bright spot after passing through this area. However, when the angle of the light beam is changed to 10°, less light is measured after transpasssing through the retina, the foveolar center becomes darker and the SCE-like phenomenon is directly visible. Measurements of the intensities of light transmission through the central foveola for the incident angles 0 and 10° resemble the relative luminance efficiency for narrow light bundles as a function of the location where the beam enters the pupil as reported by Stiles and Crawford. The effect persisted after carefully brushing away the outer segments. Conclusion We show that unique cones and Müller cells with light fibre-like properties are present in the center of the fovea. These unique Müller cells cause an angle dependent, SCE-like drop in the intensity of light guided through the foveola. Outer segments from the foveolar cones of monkeys are not straight.

A Micro-Focusing Stage Applied to Optical Pick-Up Head

2004 ◽  
Author(s):  
Chia-Wen Lee ◽  
Chung-Feng Lai ◽  
Weileun Fang
Keyword(s):  
Light Beam ◽  
Self Assembly ◽  
Focal Point ◽  
Incident Light ◽  
Disk Surface ◽  
Electrode Layer ◽  
Assembly Mechanism ◽  
Out Of Plane ◽  
Focusing Lens ◽  
Through Hole

Presently, various micromachined actuators have been employed to tune the tracking and focusing of the light beam of optical pick-up head [1–2]. This work demonstrates a novel micro-focusing stage for optical pick-up head application. As in Fig. 1a, the presented micro-focusing stage for optical pick-up head is consisted of four parts: out-of-plane actuator, connecting joint, through hole, and focusing lens plate. The stress-induced beams acted as the self-assembly mechanism to lift up focusing lens plate. In addition, the stress-induced beams also acted as the out-of-plane electrostatic actuator after deposited with an electrode layer. Unlike the design in [3], a through hole underneath the lens plate is allowed in this case for the incident light beam. After properly driving the stress-induced beams, the position of the focusing plate was controlled, as shown in Fig. 1b. The stage had piston motion to adjust the focal point of the lens. Moreover, the stage had tilt motion, so as to ensure that the lens paralleled the disk surface. Thus, the incident laser beam was always orthogonal with the disk surface.

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