Showing papers on "Diffraction efficiency published in 1982"
TL;DR: In this article, a dielectric surface-relief grating is analyzed using rigorous coupled-wave theory and the analysis applies to arbitrary grating profiles, groove depths, angles of incidence, and wavelengths.
Abstract: Diffraction by a dielectric surface-relief grating is analyzed using rigorous coupled-wave theory. The analysis applies to arbitrary grating profiles, groove depths, angles of incidence, and wavelengths. Example results for a wide range of groove depths are presented for sinusoidal, square-wave, triangular, and sawtooth gratings. Diffraction efficiencies obtained from the present method of analysis are compared with previously published numerical results. To obtain large diffraction efficiencies (greater than 85%) for gratings with typical substrate permittivities, it is shown that the grating profile should possess even symmetry.
967 citations
TL;DR: In this paper, a new formalism for the diffraction of an electromagnetic plane wave by a multicoated grating is presented, which uses a coordinate system that maps all the interfaces onto parallel planes.
Abstract: We present a new formalism for the diffraction of an electromagnetic plane wave by a multicoated grating. Its basic feature lies in the use of a coordinate system that maps all the interfaces onto parallel planes. Using Maxwell’s equations in this new system leads to a linear system of differential equations with constant coefficients whose solution is obtained through the calculation of the eigenvalues and eigenvectors of a matrix in each medium. Through classical criteria, our numerical results have been found generally to be accurate to within 1%. The serious numerical difficulties encountered by the previous differential formalism for highly conducting metallic gratings completely disappear, whatever the optical region. Furthermore, our computer code provides accurate results for metallic gratings covered by many modulated dielectric coatings or for highly modulated gratings. We give two kinds of applications. The first concerns the use of dielectric coatings on a modulated metallic substrate to minimize the absorption of energy. Conversely, the second describes the use of highly modulated metallic gratings to increase this absorption.
411 citations
TL;DR: In this paper, the photon eigenfunctions in the grating region can be expressed in analytical form, which makes the diffraction calculation not only simple and direct, but also devoid of the many limitations encountered in other solution techniques.
Abstract: We show that for dielectric or metallic gratings with square-wave geometry the photon eigenfunctions in the grating region can be expressed in analytical form. The knowledge of these eigenfunctions makes the diffraction calculation not only simple and direct, but also devoid of the many limitations encountered in other solution techniques. In particular, diffraction from deep gratings and the calculation of surface-plasmon excitations present no difficulties. Numerical results on diffraction efficiency are in good agreement with our experimental data. The near-field electromagnetic properties of Ag gratings are examined in detail. These results are of particular importance in understanding the optical behavior of molecules near a rough metal surface (for example, in surface-enhanced Raman scattering). It is shown that coincident with the excitation of surface plasmon, there is an enhancement of the local- (surface-) field intensity by a factor of 100-500. For molecules on a grating surface, such increase in local fields can imply an amplification of ${10}^{4}$-3\ifmmode\times\else\texttimes\fi{}${10}^{5}$ for the Raman scattering signal.
265 citations
TL;DR: A blazing technique using electron-beam lithography to achieve higher efficiency of gratings and Fresnel lenses is described, and the experimental results showed high-efficiency performance and nearly diffraction-limited focusing.
Abstract: A blazing technique using electron-beam lithography to achieve higher efficiency of gratings and Fresnel lenses is described. Transmission-type blazed gratings have been formed in polymethyl methacrylate films. As a result of measurement, we found that their diffraction efficiency of the first order in these gratings amounts to as much as 60 to 70% at 0.633 microm. Fresnel lenses of 1-mm diameter and 5-mm focal length, which have a sawtooth relief profile, have been also fabricated, and the experimental results showed high-efficiency performance (about 50%) and nearly diffraction-limited focusing.
166 citations
TL;DR: In this paper, it was shown that a phase volume hologram in a photorefractive crystal exists in the form of relaxing running wave, and that effective recording of such a running hologram is possible only by an interference pattern moving synchronously with the recorded grating.
132 citations
TL;DR: Kogelnik's coupled wave theory is applied to analyze the diffraction efficiency of a filter recorded on a high-efficiency phase medium such as dichromated gelatin.
Abstract: An analysis is made of the overall light efficiency in a coherent optical correlator. The results are applied to a matched filter and an inverse filter. Kogelnik's coupled wave theory is applied to analyze the diffraction efficiency of a filter recorded on a high-efficiency phase medium such as dichromated gelatin. Experimental results are presented for a matched filter and out-of-focus spatial filter, and the former is compared to the theory with good agreement.
120 citations
TL;DR: A new type of concentrating system is presented which allows high concentration and simultaneous splitting of the spectral region and is based on volume phase transmission holograms which exhibit minimum absorption, high diffraction efficiency, and adjustable dispersion.
Abstract: The efficiency of photovoltaic generators based on different semiconductor materials with optimized band gaps can achieve considerably higher values than those contained with single-junction solar cells A new type of concentrating system is presented which allows high concentration and simultaneous splitting of the spectral region This dispersive and concentrating (DISCO) system is based on volume phase transmission holograms which exhibit minimum absorption, high diffraction efficiency, and adjustable dispersion The spectral imaging properties of volume phase transmission holograms can be optimized with respect to the requirements for solar applications
70 citations
TL;DR: In this article, a simple but rigorous chain-matrix analysis is used to determine the plane-wave diffraction efficiencies and angular selectivities of planar pure-reflection gratings (zero-slant angle) of arbitrary thickness, arbitrary-starting and arbitrary-ending conditions, and arbitrary incidence angle.
Abstract: A simple but rigorous chain-matrix analysis is used to determine the plane-wave diffraction efficiencies and angular selectivities of planar pure-reflection gratings (zero-slant angle) of arbitrary thickness, arbitrary-starting and arbitrary-ending conditions, and arbitrary incidence angle. The results from rigorous coupled-wave theory in the angular limit as the fringes become parallel to the surfaces are shown to approach these results in a particular average sense.
69 citations
TL;DR: In this paper, the beam-propagation method was employed to calculate the electric field amplitude inside and outside a grating structure excited by an arbitrary incident field, and the accuracy of the method was established by comparing the results for constant-period gratings with results obtained from other theoretical methods.
Abstract: We demonstrate that the beam-propagation method can be employed to calculate the electric-field amplitude inside and outside a grating structure excited by an arbitrary incident field. We establish the accuracy of the method by comparing our results for constant-period gratings with results obtained from other theoretical methods. Subsequently, we analyze thick-focusing gratings with the beam-propagation method.
68 citations
TL;DR: In this paper, a detailed experimental study of nonlinear optical scattering in nematic liquid crystals using low-power cw lasers is presented, where the authors quantitatively measured the dependence of the diffraction efficiency as a function of the optical intensity and magnetic field ranging from well below to far above the critical orientation threshold values.
Abstract: We present here a detailed experimental study of nonlinear optical scattering in nematic liquid crystals using low-power cw lasers. The scattering is effected by the phase grating created by two intersecting same-frequency lasers. These lasers interfere spatially to create an index modulation via their reorientation effects on the molecules. When aided by a dc magnetic field, the reorientation and nonlinear responses of the medium are enhanced. We have quantitatively measured the dependence of the diffraction efficiency as a function of the optical intensity and the magnetic field ranging from well below to far above the critical orientation threshold values. The scattering is also analyzed in terms of its dependence on the temperature, sample thickness, and the scattering geometry. The experimental results are in good agreement with theoretical expectations. We also point out some high-intensity effects and applications of this phase grating, e.g., in wave-front conjugation and holographic imaging.
51 citations
TL;DR: In this article, an analytic procedure for recording a flat, volume-phase-transmission holographic optical element at a wavelength different from that at which it is to be used was derived.
Abstract: We have derived an analytic procedure for recording a flat, volume-phase-transmission holographic optical element at a wavelength different from that at which it is to be used. The procedure guarantees that the resulting element will have diffraction-limited aberration performance. Furthermore it guarantees, to a first order, that the Bragg condition for high diffraction efficiency will be satisfied. The technique gives simple analytic expressions for the required object and reference construction-beam phases at the element. In general, the object and reference construction beams must be realized by using computer-generated holograms in conjunction with conventional refractive or reflective optics.
TL;DR: In this paper, a spatially periodic distribution of electronhole pairs has been produced in silicon crystals by excitation with a pulsed neodymium yttrium aluminum garnet (Nd: YAG) laser.
Abstract: A spatially periodic distribution of electron‐hole pairs has been produced in silicon crystals by excitation with a pulsed neodymium yttrium aluminum garnet (Nd: YAG) laser. The diffraction efficiency and the decay time of the grating structure has been measured by diffraction of an independent quasi‐cw laser beam as a function of the energy density of the exciting laser. At low energy‐densities the diffraction efficiency is given by a squared Bessel function dependent on the carrier density as expected from theory. At higher incident energy densities deviations occur which can be explained by free‐carrier absorption and intensity fluctuations across the beam. The grating decay time is determined by ambipolar diffusion and Auger recombination.
TL;DR: Results show that conical diffraction is capable of producing very high dispersion efficiencies, and the most immediate application is to X-ray astronomy where sources are weak.
Abstract: The efficiency of X-ray diffraction from reflection gratings has been investigated experimentally using a gold-coated plane grating of 25 x 120 mm with a nominal blaze angle of 21 deg in a conical diffraction mount. Results show that conical diffraction is capable of producing very high dispersion efficiencies. The peak of first order at 13.3 A is 40%; at 44 A, the peak is 34%. The most immediate application of this result is to X-ray astronomy where sources are weak.
TL;DR: The proposed method permits quasi-nondestructive readout of a phase-volume grating in BSO atlambda(R) = 840 nm (semiconductor laser) while recording is done by interference of two incident and collinear beams at lambda(1) = 632.8 (He-Ne laser) and lambda(2) = 514.5 (Ar laser).
Abstract: We demonstrate the possibility of collinear Bragg diffraction in photorefractive Bi12SiO20 (BSO) crystals of two incident writing and readout beams of different wavelengths. Two grating wave vectors K1 and K2 are created by interference of independent and collinear beams at wavelengths λ1 and λ2. In the photorefractive medium the nonlinearities of the photoinduced space-charge field generate the new grating wave vectors KNL = mK1 ± nK2. Bragg diffraction is thus achieved at a readout wavelength λR such as 1/λR = (m/λ1) ± (n/λ2). The proposed method permits quasi-nondestructive readout of a phase-volume grating in BSO at λR = 840 nm (semiconductor laser) while recording is done by interference of two incident and collinear beams at λ1 = 632.8 (He–Ne laser) and λ2 = 514.5 (Ar laser).
IBM1
TL;DR: Two-photon holographic recording with cw laser sources in the 750-1100-nm spectral range is accomplished using recording materials consisting of an alpha-diketone dissolved in a poly-alpha-cyanoacrylate host.
Abstract: Two-photon holographic recording with cw laser sources in the 750–1100-nm spectral range is accomplished using recording materials consisting of an α-diketone dissolved in a poly-α-cyanoacrylate host. Gating of the holographic sensitivity by irradiation with incoherent UV radiation is demonstrated. Hologram diffraction efficiencies as large as 10% are achieved.
TL;DR: In this paper, the approximate bandwidth and diffraction efficiency for thick holograms are derived in an extremely simplified fashion from considerations of the geometry of the holograms alone, and the results agree with the exact expressions derived from coupled wave theory and afford a far more direct insight into the effect of various geometric and material parameters with the hologram performance.
Abstract: The approximate bandwidth and diffraction efficiency (DE) for thick holograms are derived in an extremely simplified fashion from considerations of the geometry of the holograms alone. The results agree with the exact expressions derived from coupled wave theory and afford a far more direct insight into the effect of the various geometric and material parameters with the hologram performance.
TL;DR: Layered synthetic microstructures (LSM's) as mentioned in this paper are useful dispersing devices for x-ray spectroscopy, and they can be produced with virtually any layer spacing (d) greater than approximately 10 A and they have high diffraction efficiency.
Abstract: Layered synthetic microstructures (LSM's) are useful dispersing devices for x-ray spectroscopy. They can be produced with virtually any layer spacing (d) greater than approximately 10 A and they have high diffraction efficiency. Integral reflection coefficients for such structures made up of alternating layers of a transition metal and carbon are 3 to 10 times greater than values for other dispersing elements used in the moderate to long wavelength region of the x-ray spectrum. Resolving power of the LSMs is somewhat poorer than crystals at this time but is sufficient to permit significant applications.
TL;DR: In this article, a numerical technique based on the mode-matching method with a smoothing procedure is presented for analyzing the diffraction of electromagnetic waves by a grating, and it is demonstrated that the sequence of approximate solutions calculated by the algorithm presented in this paper converges to the true solution much faster than the sequence produced by the conventional mode matching method.
Abstract: A numerical technique based on the mode-matching method with a smoothing procedure is presented for analyzing the diffraction of electromagnetic waves by a grating. The general algorithm for the problem of an arbitrarily shaped periodic surface is described taking the case of H polarization. To show the validity of this algorithm, plane-wave diffraction by a triangular grating is analyzed, and the results are compared with those obtained by the conventional mode-matching method. It is demonstrated that the sequence of approximate solutions calculated by the algorithm presented in this paper converges to the true solution much faster than the sequence produced by the conventional mode-matching method. Some numerical examples on the efficiency are presented.
01 Dec 1982
TL;DR: In this paper, a cross-channel A0 module with a 50% diffraction efficiency and a bandwidth of 13.4 MHz with 0.13 watt of surface acoustic wave power centered at 320 MHz is presented.
Abstract: A high diffraction efficiency acoustooptic deflector/modulator using single-mode crossedchannel waveguides in a Y-cut LiNb03 substrate has been realized. A 50% diffraction efficiency and a bandwidth of 13.4 MHz were obtained with 0.13 watt of surface acoustic wave power centered at 320 MHz. This result clearly indicates the feasibility for realization of an active integrated optic module with a 50-50 power split and a tunable frequency offset. Consequently, this crossed-channel A0 module should find a variety of applications in integrated and fiber optic systems.
Patent•
02 Feb 1982
TL;DR: In this paper, the optical Fourier transformer device supplying the correlation function of two motifs of an object illuminated in coherent light by using the double diffraction principle is essentially characterized in that it generates a complex wave conjugate of a wave propagating in the opposite direction to the latter.
Abstract: This optical Fourier transformer device supplying the correlation function of two motifs of an object illuminated in coherent light by using the double diffraction principle is essentially characterized in that it generates a complex wave conjugate of a wave modulated by the object propagating in the opposite direction to the latter. This conjugate wave is produced by double diffraction in an interaction medium and compensates the distortions induced by the optical components of the system. The optical correlator system utilizing this Fourier transformer is essentially characterized in that it uses a recyclable material as the recording medium. A reading beam is subject to an angular scan making it possible to optimize the diffraction efficiency of this medium. The beam modulated by the object and the reading beam are synchronously deflected to improve the signal to noise ratio in the output plane.
TL;DR: The diffraction efficiency, bandpass, and spurious beam rejection are studied for the holographic cascade lens that consists of a diffraction grating in contact with an off-axis zone plate.
Abstract: The diffraction efficiency, bandpass, and spurious beam rejection are studied for the holographic cascade lens that consists of a diffraction grating in contact with an off-axis zone plate An analysis is presented for the bandpass of the volume diffraction grating, including the effects of grain polarizability
TL;DR: Color-coded, simultaneous recognition of several characters is experimentally performed using wavelength-triplexed, reflection-type holographic filters made with the primary wavelengths, 632.8, 514.5, and 488.0 nm.
Abstract: Color-coded, simultaneous recognition of several characters is experimentally performed using wavelength-triplexed, reflection-type holographic filters made with the primary wavelengths, 632.8, 514.5, and 488.0 nm. Helpful data on the diffraction efficiency and the spectrally diffracted intensity of reflection-type holograms are presented.
TL;DR: In this article, a variational theory is presented that describes the diffraction properties of perfectly conducting gratings in TE polarization and solves the problem of the energy distribution of light diffracted by gratings with periodic errors.
Abstract: A variational theory is presented that describes the diffraction properties of perfectly conducting gratings in TE polarization. By using this formalism we solve the problem of the energy distribution of light diffracted by gratings with periodic errors.
TL;DR: In this article, a new type of holographic optical element is demonstrated which combines some of the flexibility of computer generated holograms with the large space-bandwidth product and high diffraction efficiency of interferometrically recorded volume phase holograms.
Abstract: A new type of holographic optical element is demonstrated which combines some of the flexibility of computer generated holograms with the large space-bandwidth product and high diffraction efficiency of interferometrically recorded volume phase holograms. The optical element is recorded by subdividing a volume hologram film surface into numerous small areas (facets), each of which is individually exposed under computer control. Each facet is used to produce a portion of the desired final wavefront. This new method allows the rapid production of high efficiency, customized, space-variant optical elements. A holographic cylindrical lens which has greater than 90% light efficiency and forms a line focus on a curved surface is demonstrated.
TL;DR: In this article, various methods for the recording of blazed holographic diffraction gratings are presented and the regions in the wavelength-groove density plane for which they can be used are shown.
Abstract: Various methods for the recording of blazed holographic diffraction gratings are presented and the regions in the wavelength-groove density plane for which they can be used are shown. The gratings are made in the positive photoresist Shipley AZ-1350. The diffraction efficiency for s and p polarization was measured as a function of wavelength and angle of incidence. An absolute efficiency of 80% was achieved.
26 Feb 1982
TL;DR: In this paper, an analytic procedure for recording a flat, volume phase, transmission holographic optical element at a wavelength different from that at which it is to be used was derived, which guarantees that the resulting element will have diffraction limited aberration performance.
Abstract: We have derived an analytic procedure for recording a flat, volume phase, transmission holographic optical element at a wavelength different from that at which it is to be used. The procedure guarantees that the resulting element will have diffraction limited aberration performance. Furthermore, it guarantees, to a first order, that the Bragg condition for high diffraction efficiency will be satisfied. The technique gives simple analytic expressions for the required object and reference construction beam phases at the element. In general, the object and reference construction beams must be realized using computer generated holograms in conjunction with conventional refractive or reflective optics.
Patent•
19 Feb 1982TL;DR: In this paper, a polarizing beamplitter was used as a beam-splitter in conjunction with a surface relief transmission grating to achieve high diffraction efficiency for S component light and high transmittance for P component light.
Abstract: A polarizing beamsplitter device uses as a beamsplitter a surface relief transmission grating (26) formed so as to have a high diffraction efficiency for S component light and a high transmittance for P component light. In one embodiment relating to a laser read/write system, the grating is used in conjunction with a wave retardation device (28). In this embodiment, light (22) from a laser (20) is incident at about 45° onto the grating (26). The diffracted S component, which leaves the beamsplitter perpendicularly to the incident beam, passes through a λ/4 wave retardation plate (28) and is focussed by lens (30) onto a video disc (24). Reflected light passes back through the lens and the wave retardation plate, emerging from the plate (28) as a P polarized beam. This beam passes straight through the grating (26) to fall on a detector (32).
TL;DR: A switching matrix using electrooptic Bragg diffraction switches in a planar waveguide is described and low cross talk is obtained because the wave propagation in a Planar Waveguide eliminates all waveguide junctions.
Abstract: A switching matrix using electrooptic Bragg diffraction switches in a planar waveguide is described. Low cross talk is obtained because the wave propagation in a planar waveguide eliminates all waveguide junctions. Furthermore, the connections between input and output ports are formed by using the ON position of the Bragg diffraction switches only. In their OFF position, the electrooptic Bragg diffraction switches do not adversely affect the laser beams which propagate through them.
01 Jan 1982
TL;DR: In this article, a holographic lens for sound waves has been constructed and its imaging properties investigated theoretically and experimentally, and the advantages of holographic lenses over both conventional lenses and phased arrays are discussed.
Abstract: A holographic lens for sound waves has been constructed and its imaging properties investigated theoretically and experimentally. First we discuss the advantages of holographic lenses over both conventional lenses and phased arrays. Then we use the techniques described in a separate paper for a theoretical study of the image quality and diffraction efficiency of the holographic lens. Finally, we compare the theoretical results with those obtained in a water tank experiment.
TL;DR: In this article, the local diffraction efficiency of a lens was analyzed by assuming that both the direction and magnitude of the grating vector are constant over a small area of the hologram.
Abstract: Lenses are formed in bleached photographic emulsion, and the local diffraction efficiency into the various diffraction orders is determined using a probe beam of small diameter. An analysis of the lens is performed by assuming that both the direction and magnitude of the grating vector are constant over a small area of the hologram, leading to ordinary (in contrast to more rigorous partial) differential equations which may be solved numerically. Comparison of experimental results with numerical analysis shows reasonable agreement.