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Showing papers on "Total internal reflection published in 1975"


Journal ArticleDOI
TL;DR: In this paper, the authors describe a simple experiment and theory for a senior level undergraduate investigation of surface plasmons in silver films, where an ∠500-A-thick film is evaporated on the hypotenuse face of a right glass prism.
Abstract: Surface plasmon phenomena are a topic of considerable current interest. We describe a simple experiment and theory for a senior level undergraduate investigation of surface plasmons in silver films. An ∠500‐A‐thick silver film is evaporated on the hypotenuse face of a right glass prism. Light (p‐polarized) from a He–Ne laser is incident through the prism on the metal film. At an angle of incidence a few degrees greater than the critical angle for total reflection, a sharp minimum in the reflected light is observed, corresponding to the excitation of the surface plasmon. The minimum in the reflectivity results from the absorption of the resonantly enhanced surface plasmon mode in the silver film. The dispersion relation for the surface plasmon and the reflectivity due to the excitation of this normal mode are calculated. Only a modest vacuum of ∠10−3 Torr is necessary to produce the required thin silver films.

95 citations


Journal ArticleDOI
Abstract: The reflection of a locally plane wave from a curved interface between two nonabsorbing dielectric media is investigated. Our analysis is applicable to an interface of general shape, defined at each point by the two principal radii of curvature. When the wave is incident from the denser medium at angles greater than the critical angle it is only partially reflected, due to a form of electromagnetic tunneling. Generalized Fresnel transmission coefficients and an extension of Snell's law are derived to account for this transmission into the less dense medium. Ray tracing can then be applied to determine such phenomena as the bending losses in optical slab waveguides, and the curvature loss of skew rays within straight optical waveguides of circular cross section.

86 citations


Journal ArticleDOI
TL;DR: In this article, the design steps for single-reflection retarders are briefly stated and applied to the SiO2-Si film-substrate system at wavelength 6328 A. The criterion of minimum-maximum error of the ellipsometric angle ψ is used to choose angle-of-incidence-tunable designs.
Abstract: The design steps for film–substrate single-reflection retarders are briefly stated and applied to the SiO2–Si film–substrate system at wavelength 6328 A. The criterion of minimum-maximum error of the ellipsometric angle ψ is used to choose angle-of-incidence-tunable designs. Use is made of the (ϕ-d) plane (angle of incidence versus thickness) to determine whether a given film–substrate system with known optical properties and film thickness can operate as a reflection retarder and to determine the associated angles of incidence and retardation angles. This leads to the concept of permissible-thickness bands and forbidden gaps for operation of a film–substrate system as a reflection retarder. Experimental measurements on one of the proposed designs proved the validity of the method.

35 citations


Journal ArticleDOI
TL;DR: In this paper, the influence of the pelletizing pressure on the frequency of the O-H stretching vibration at 3640 cm−1 has been studied up to 7000 kp/cm2 for CaY and NH4-Y zeolites by means of internal reflection and transmission techniques.

33 citations


Journal ArticleDOI
TL;DR: A scheme of combined reflection and transmission ellipsometry on light-transmitting ambient-film-substrate systems is proposed and the required sample design and instrument operation are investigated and the ranges of validity of the linear approximations are comparable.
Abstract: A scheme of combined reflection and transmission ellipsometry on light-transmitting ambient–film–substrate systems is proposed and the required sample design and instrument operation are investigated. A comparative study of the sensitivity of external and internal reflection and transmission ellipsometry is carried out based on unified linear approximations of the exact equations. These approximations are general in that an arbitrary initial film thickness is assumed. They are simple, because a complex sensitivity function is introduced whose real and imaginary projections determine the psi (ψ) and delta (Δ) sensitivity factors. Among the conclusions of this paper are the following. (1) External reflection ellipsometry near the Brewster angle of a transparent ambient–substrate system is extremely sensitive to the presence of very thin interfacial films. For example, films as thin as 10−5 A of gold are readily detectable on glass substrates at an angle of incidence 0.3° below the Brewster angle, assuming a measuring wavelength of 5461 A with an ellipsometer of 0.05° precision. (2) The formation of thin nonabsorbing films at the interface between transparent ambient and substrate media is not detectable, to first order, as a change in the ellipsometric angle ψ by either internal or external reflection or transmission ellipsometry. (3) The film-detection sensitivity of transmission ellipsometry increases monotonically with angle of incidence. (4) For each angle of external incidence there is a corresponding angle of internal incidence that leads to the same values of the reflection and transmission sensitivity functions. These angles are interrelated by Snell's law. (5) The ranges of validity of the linear approximation in reflection and transmission ellipsometry are comparable. The case of total internal reflection ellipsometry may lead to strong nonlinear behavior of ψ and Δ as functions of the film thickness in the range below 0.05 of the wavelength of light.

32 citations


Journal ArticleDOI
TL;DR: In this article, a change in the decay mechanism is shown to result from the increasing angle of incidence between the shock and an intersecting cylindrical (or spherical) wave generated behind it.
Abstract: In the analysis of shock stability reported, the disturbances are assumed to originate at an arbitrary moving point. A change in the decay mechanism is shown to result from the increasing angle of incidence between the shock and an intersecting cylindrical (or spherical) wave generated behind it. The local reflection coefficient for reflection of a pressure wave from a shock varies strongly with the angle of incidence. At small angles of incidence the reflected wave is very weak and the incident wave decays in a geometric manner.

27 citations


Journal ArticleDOI
TL;DR: In this article, the problem of reflection of electromagnetic waves from oscillating surfaces is discussed using the induction theorem, where the interface is replaced by equivalent current sources that radiate into an unbounded medium.
Abstract: The problem of reflection of electromagnetic waves from oscillating surfaces is discussed. Using the induction theorem, the interface is replaced by equivalent current sources that radiate into an unbounded medium. Spatial movement is ascribed to these sources to account for oscillations of the surface. The general solution for the far-field due to any arbitrary surface motion is developed. A few deterministic and random functions for surface motion are considered. Most of the initial discussion pertains to normal reflection from planar surfaces, but the solution is also obtained for arbitrary incidence and for an oscillating cylinder.

25 citations


Patent
Joel M. Pollack1, John B. Flannery1
25 Feb 1975
TL;DR: In this paper, the bistable deflection of a beam of light into and out from a layer of nematic liquid crystalline material having negative dielectric anisotropy and having a thickness of from about 1 micron to about 6 microns is achieved by providing the nematic surface material in the parallel variable grating mode between two electrodes, the material being under an applied voltage between the two electrodes at a voltage level above the threshold voltage level for parallel variable diffraction mode for said material, and increasing and decreasing the applied voltage so that light diffracted by
Abstract: Bistable deflection of a beam of light into and out from a layer of nematic liquid crystalline material having negative dielectric anisotropy and having a thickness of from about 1 micron to about 6 microns is achieved by providing the nematic liquid crystalline material in the parallel variable grating mode between two electrodes, the nematic being under an applied voltage between the two electrodes at a voltage level above the threshold voltage level for parallel variable diffraction mode for said nematic liquid crystalline material, and increasing and decreasing the applied voltage so that light diffracted by the parallel variable grating mode nematic is deflected at an angle which either exceeds or is less than the critical angle between the layer of nematic liquid crystalline material and one of the electrodes. When the deflection of diffracted light is increased in excess of the critical angle, the incident light is totally reflected within the nematic layer; and, when the deflection angle of the diffracted light is decreased below the critical angle, the incident light is diffracted through the nematic layer and the one electrode. The bistable deflection can be utilized in a reproduction device which converts a data chain of electrical signals into an image and in integrated optics.

20 citations


Patent
13 Nov 1975
TL;DR: In this article, the pn junction emitting the optical radiation is located in or near the hilly surface of the semiconductor material, which can be of different geometric shapes, such as triangular, pyramid or cone shaped.
Abstract: Optical semiconductor source of radiation with one or both regions having a hilly surface. The device has a pn junction between two regions of different type conductivity. In this device the total reflection losses are considerably reduced and maximum use is made of the material. The hilly outer surface can be of different geometric shapes, such as triangular, pyramid or cone shaped. In the case of the triangle, the apex angle is approximately twice that which will produce total internal reflection. The pn junction emitting the optical radiation is located in or near the hilly surface.

19 citations


Journal ArticleDOI
TL;DR: Internal reflection spectrometry, using a high refractive index, infrared-transparent prism such as germanium, provides the thin sampling region necessary to avoid the total loss of energy at the water peak maxima and is able to obtain accurate spectra of aqueous proteins by subtraction of the solvent spectrum from that of the solution.
Abstract: For twenty years, infrared spectrometrists have relied on the positions and intensities of the N-H stretching, amide I (primarily C=O stretch), and amide I1 (C-N stretch + NH bend) bands as aids in interpreting the secondary structures of synthetic polypeptides and natural proteins. These three absorption bands provide essentially all of the secondary structural information that can be obtained from the infrared spectrum of a polypeptide ( I ) . Two of the bands however, the N-H stretching band at approximately 3400 cm-l and the amide I band at about 1650 cm-', are effectively obscured in aqueous solution spectra by the -3380 cm-l and 1639 cm-l bands of liquid water. Various efforts to get around this problem have been employed, including the use of D20 as a solvent, employing very thin cells, or using a compensating reference cell (2-4) . T h e thin cell technique (2-4) is inadequate for protein solution spectrometry because of the concomitant requirement of high solute concentrations. DzO solutions pose an additional problem, tha t of hydrogen-deuterium exchange. This results in a change in the intensity of the undeuterated amide TI band, and formation of a deuterated amide I1 band a t the same frequency as the HDO band ( I ) . Internal reflection spectrometry ( 4 ) , using a high refractive index, infrared-transparent prism such as germanium, provides the thin sampling region necessary to avoid the total loss of energy at the water peak maxima. For an internal reflection system, the "depth of penetration,'' d,, is defined (41 as the distance into the solution where the evanescent field amplitude decays to e-l of its magnitude at the prism-solution interface. For germanium-water, a t a 45" angle of incidence, this distance is 0.064 XO, where Xo is the in-uacuo wavelength (5, 6). Eighty-four percent of the peak intensity observed in an internal reflection spectrum is derived from absorbing molecules within one d, of the prismsolution interface, and 95% of the observed peak intensity is due to molecules within two d,. Thus, for the amide I peak a t 1650 cm-l, 95% of the band intensity comes from the 7750-A thin region at the germanium-solution interface. This is true for the zero absorption case, but is also applicable for low values of k. Higher values (20.1) of h will depress d, (3) . Using such a thin sampling region in combination with the signal-to-noise enhancing techniques of spectrum-averaging and mathematical smoothing, we have been able to obtain accurate spectra of aqueous proteins by subtraction of the solvent spectrum from that of the solution. Spectrum subtraction was demonstrated by Yang and Low (7) , using a Fourier transform interferometer, for aqueous nitrate and nitrite solutions. but their use of difference spectra was restricted to regions where water bands would not interfere. In this paper, we show that, with the aid of a minicomputer interfaced to a standard dispersive infrared spectrophotometer, the obscured amide I band of a protein can be separated from the overlying water band at 1639 cm-'.

17 citations


Journal ArticleDOI
TL;DR: A model based on frustrated total reflection of waves in a multilayered medium has been developed to analyze the crosstalk between multimode optical fibers, and Kappa (κ), the parameter indicating the power distribution among the modes of the fiber, and fiber cladding thickness play very important roles in determining the c Crosstalk isolation between fibers.
Abstract: A model based on frustrated total reflection of waves in a multilayered medium has been developed to analyze the crosstalk between multimode optical fibers. Kappa (κ), the parameter indicating the power distribution among the modes of the fiber, and fiber cladding thickness play very important roles in determining the crosstalk isolation between fibers. Significant but less dominant effects on crosstalk are due to variations in fiber numerical aperture, length, and transmitting wavelength.

Patent
30 Jun 1975
TL;DR: In this paper, an optical fan system for projecting a planar fan of light against a surface is described. Butler et al. presented a method for projecting the fan on a translucent or transparent body, where a source of collimated light is passed into an edge face bridging between two cylindrical concentric reflective surfaces defining outer surfaces.
Abstract: This invention provides an optical fan system for projecting a planar fan of light against a surface. A source of collimated light is passed into an edge face bridging between two cylindrical concentric reflective surfaces defining outer surfaces of a translucent or transparent body. The light refracts through the edge face, and then is multiply reflected and refracted between the concentric cylindrical surfaces, with total reflection occurring at the internal surface and partial refraction occurring at the outer surface. Suitable silvering or other reflective material is applied to the surfaces in order to accomplish the desired degree of reflectivity.

Patent
23 Dec 1975
TL;DR: In this paper, a method of splitting two diverging beams of energy from a single beam of energy including the steps of splitting the single beam energy into an externally reflected beam and an internally transmitted beam at a first surface on a wedge shaped energy beam splitting device, and substantially totally reflecting the internal reflected beam between the first and second surfaces until the internally reflected beam reaches an end of the wedge shaped EH device, is presented.
Abstract: A method of forming two diverging beams of energy from a single beam of energy including the steps of splitting the single beam of energy into an externally reflected beam and an internally transmitted beam at a first surface on a wedge shaped energy beam splitting device; splitting the internally transmitted beam into an internally reflected beam and an externally transmitted beam at a second surface of the wedge shaped energy beam splitting device, and substantially totally reflecting the internally reflected beam between the first and second surfaces until the internally reflected beam reaches an end of the wedge shaped energy beam splitting device. The above method may further include steps paralleling the above steps wherein two diverging beams of energy are formed from a second beam of energy impinging on the second surface and then combining the two diverging beams with the two diverging beams formed from the beam of energy split by the first surface, to form first and second combined beams. The preferred apparatus for performing the method is an energy beam splitting device having a first surface for splitting an incident beam energy into an externally reflected beam and an internally transmitted beams, a second surface spaced from the first surface for splitting the internally transmitted beam into an externally transmitted beam and into an internally reflected beam, and the second surface intersecting the first surface at an angle that impinges the internally transmitted beam on the second surface at an angle of incidence that is less than the minimum angle necessary for substantially total internal reflection and impinges said internally reflected beam on the first surface at an angle of incidence that exceeds the minimum angle necessary for substantially total internal reflection. The above device may further be used as a beam combiner by having the second surface split a second incident beam of energy into two diverging beams of energy and combining the two beams produced by the first surface with the two beams produced by the second surface to form first and second combined beams.

Journal ArticleDOI
TL;DR: Two-dimensional optical effects were observed for surface electromagnetic waves (SEW) on metals at lambda = 3.55 cm and it was shown that the propagation constant of the Sew with an overlayer material is as though the SEW propagates entirely in the overlayermaterial.
Abstract: Two-dimensional optical effects were observed for surface electromagnetic waves (SEW) on metals at λ = 3.55 cm. Refractive processes with prisms and lenses established Snell's law experimentally. Reflection with prisms and metal sheets established the law of reflection and indicated that radiative losses were small and that Fresnel's equations hold to a good approximation for the reflectivities of SEW. A two-dimensional SEW grating was made and first-order diffraction observed. Although the experiments were performed at microwave frequencies, the principles are usable for two-dimensional SEW optics at least as far as the near ir. It was shown that the propagation constant of the SEW with an overlayer material is as though the SEW propagates entirely in the overlayer material. That is, losses in the metal substrate were negligible.

Patent
06 Nov 1975
TL;DR: In this article, a light source is placed on one side of a rectangular optical prism, and a photoelectric transducer on the other, so that by use of additional means, such as mirrors and lenses with a diaphragm, a parallel light beam is produced perpendicular to the prism cathetuses and spread if possible over the whole cathetus surface.
Abstract: A light source is placed on one side of a rectangular optical prism, and a photoelectric transducer on the other, so that by use of additional means, such as mirrors and lenses with a diaphragm, a parallel light beam is produced perpendicular to the prism cathetuses and spread if possible over the whole cathetus surface; it is reflected by total reflection from the outer surface of the tested glass plate, to whose inner surface the prism hypotenuse surface is cemented by an optical cement; the beam is partly diverted outward by wetting of the outer surface. Alternatively, two similar prisms with the same auxiliary equipment are used, so that the beam of light is reflected several times by the glass plate surfaces before it emerges from the second prism.

Journal ArticleDOI
TL;DR: In this article, the behavior of neutrons in magnetic fields varying harmonically in time or space is treated, and the results are applied to the reflection and transmission of the neutrons at helical structures.
Abstract: The behaviour of neutrons in magnetic fields varying harmonically in time or space is treated. For the case of time-dependent fields the movement of the spins is followed in detail. For the case of helical fields the general solution of the Pauli-equation is given. It is shown that for neutrons a helicalB-field is representing a medium with quite general properties of double-refraction. The formal connection between the solutions for both cases of the field is discussed. The results are applied to the reflection and transmission of neutrons at helical structures. It is shown that a critical angle exists corresponding to the angle of total reflection, but being greater than this and increasing with increasing helicity. A further main consequence of the helix field is that always a part of the reflected wave has flipped spins its intensity depending on the polarization of the incident wave.

Journal ArticleDOI
Ryosuke Sato1
TL;DR: In this article, the authors compared theoretical seismograms due to a moving fault in a layered medium with those in an infinite and a semi-infinite medium and concluded that the difference is significant.
Abstract: Recently, determinations of focal parameters have been widely investigated by comparing observed seismograms with synthesized ones. As a source model, the dislocation model has been accepted as a realistic one, since it was introduced in the field of seismology. For the medium, however, in almost all the studies a very simple model such as an infinite or a semiinfinite medium is assumed. In this case, one should recognize limitations in the appropriateness of the assumption.In the present study, theoretical seismograms due to a moving fault in a layered medium are compared with those in an infinite and a semi-infinite medium. The results are summarized as follows:Roughly speaking, if waves are incident on each interface of the layered medium with a small angle of incidence, then the seismograms in the simple medium differ little from those in the layered medium. But even for this case, if the infinite medium is assumed, one should take account of the development of the surface SP waves and Rayleigh waves, contributed from the upper part of the fault. If the angle of incidence is so large that almost total reflection takes place at the lower boundary beneath the source, the difference is significant. For this case, computations on only major phases are recommended to save computation time, referring to the reflection and transmission coefficients at each boundary due to the incidence of the plane wave. Waves which undergo P-S or S-P conversion at the boundary are in general not major phases.It seems quite difficult and not practical to obtain synthesized seismograms of particle accelerations because of inadequate accuracy and long computation time. It is better to estimate the maximum acceleration using the rough relation (maximum acceleration)=(maximum velocity/rise time).

Journal ArticleDOI
TL;DR: In this article, the significant parameters for plastic fibres with various core/cladding combinations are given: refractive index, numerical aperture, critical angle of total internal reflection at the core and cladding interface and maximum angle of aperture.
Abstract: The significant parameters for plastic fibres with various core/cladding combinations are given: refractive index, numerical aperture, critical angle of total internal reflection at the core/cladding interface and maximum angle of aperture. The output power of a plastic fibre (PS/PMMA) was measured as a function of the angle of incidence. The results are interpreted using the ray optical fibre transmission model.

Journal ArticleDOI
TL;DR: In this paper, the exact attenuation and power-transmission coefficients for all weakly refracting and tunnelling rays were derived for incidence from the core at arbitrary angles to the curved interface of the nonabsorbing optical waveguide of circular cross section.
Abstract: Exact attenuation and power-transmission coefficients are derived to describe the radiation loss of all weakly refracting and tunnelling rays, for incidence from the core at arbitrary angles to the curved interface of the nonabsorbing optical waveguide of circular cross section. The power-transmission coefficients are expressible as simple functions of the classical Fresnel coefficients for a planar interface. An extension to Snell’s classical laws is introduced for tunnelling rays. For such rays, curvature of the interface rotates the plane of the normal and emergent transmitted ray relative to the plane of incidence.

Patent
25 Feb 1975
TL;DR: In this article, the authors describe a method for the deflection and modulation of monochromatic light by providing an about 1 micron to about 6 micron thick layer of homogeneously aligned nematic liquid crystalline material having negative dielectric anisotropy between two transparent electrodes.
Abstract: OF THE DISCLOSURE Deflection and modulation of monochromatic light is achiev d by providing an about 1 micron to about 6 micron thick layer of homogeneously aligned nematic liquid crystalline material having negative dielectric anisotropy between two trans-parent electrodes; applying a voltage between the two electrodes at a voltage level above the threshold voltage level for parallel variable diffraction mode for said nematic liquid crystalline material, directing a ribbon or beam of monochromatic light into the layer of nematic liquid crystalline material and coplanar therewith; and increasing and decreasing the applied voltage so that light diffracted by the parallel variable grating mode nematic is deflected at an angle which either exceeds or is less than a critical angle .theta.c. When the deflection of diffracted light is in-creased in excess of critical angle .theta.c the incident monochromatic light is diffracted through the nematic layer and the electrodes; and, when the deflection angle of the diffracted light is decreased below critical angle .theta.c the incident monochromatic light is totally reflected within the nematic layer provided the voltage level is above the parallel variable grating mode level. At voltages below the parallel variable grating mode threshold voltage level, the incident monochromatic light passes through the layer of nematic liquid crystalline material without reflection. Imaging devices utilizing the above deflection and modulation are disclosed.

Journal ArticleDOI
TL;DR: An efficient beam splitter for a Michelson interferometer can be made from a pair of prisms, using the process of frustrated total internal reflection as mentioned in this paper, which vanishes for all polarizations.
Abstract: An efficient beam splitter for a Michelson interferometer can be made from a pair of prisms, using the process of frustrated total internal reflection. Although the phases and irradiances of the beams reflected and transmitted by the beam splitter depend on the polarization, the phase difference between the two interferometer beams vanishes for all polarizations and the transmittance can be made polarization insensitive by suitable design. The interferometer transmits radiant power within a wavelength band approximately two octaves wide, and rejects all other radiant power. The design, laboratory tests, and astronomical applications of an interferometer for the millimeter and submillimeter regions are discussed. An observation of the day-sky spectrum is presented.

Journal ArticleDOI
TL;DR: In this paper, a nonlinear surface−wave propagation over plasmas and conductors has been investigated when the nonlinearity in the complex dielectric constant arises on account of ponderomotive force and energy-dependent collisions.
Abstract: An investigation of nonlinear surface−wave propagation over plasmas and conductors has been carried out when the nonlinearity in the complex dielectric constant arises on account of ponderomotive force and energy−dependent collisions. Analytical expressions have been obtained for the decay rate and phase velocity of the evanescent wave in the limit of perturbation approximation. The nonlinearity is found to reduce the rate of decay of an evanescent wave in a conductor and also in the case of a dense plasma. A study of the phenomenon of total internal reflection reveals that the critical angle increases due to nonlinearity and the evanescent wave decays slower.

Journal ArticleDOI
TL;DR: In this paper, the shape of the reflected beam has the same form as an original beam when incident anlge φ is equal to the critical angle defined by φc=cos−1[({1±[1−2b (Z0+L)]1/2}/2)1/ 2].
Abstract: For the purpose of radio and optical propagation, it is of practical importance to study how the shape of a Gaussian beam is deformed by a total reflection from an inhomogeneous medium. A fundamental problem, where the two‐dimensional Gaussian beam is obliquely incident on the boundary surface between a homogeneous half‐space and an inhomogeneous half‐space whose permittivity decreases linearly in one direction, is analyzed. The theoretical result obtained by means of a Fourier transform is valid for cases of a collimated beam and a slowly varying medium. The characteristics of the reflected beam after it has propagated through the inhomogeneous medium are discussed. It is found for the first time that the shape of the reflected beam has the same form as an original beam when incident anlge φ is equal to the critical angle defined by φc=cos−1[({1±[1−2b (Z0+L)]1/2}/2)1/2]. When φ is not equal to φc, the reflected beam is deformed compared with the original beam.

Journal ArticleDOI
TL;DR: In this paper, the authors describe the use of a computer program for the evaluation of elastic moduli of solid media, from data obtained using the critical angle reflection technique, expressed in terms of the longitudinal modulus K = λ + 2 μ, where λ and μ are the Lame constants.

Journal ArticleDOI
TL;DR: A theory that can be used to compute ray trajectories in the tapered regions and an expression similar to the critical angle in total specular reflection for the maximum acceptance angle that happens to be approximately 42 degrees for the authors' structure are developed.
Abstract: We propose a tapered edge ridge (TER) waveguide as a flexible means for interconnecting devices in integrated optics. Since the guiding film itself is in the form of a ridge, the maximum acceptance angle can be very large. The tapered edges of the ridge help to make the scattering losses negligible. Our experiments with a tantulum oxide guide on a 7059 glass substrate show that scattering losses from the tapered edges are small if any. We have coupled light at 20° to waveguide axis with light propagation occurring with no apparent loss from scattering at the edges. We have developed a theory that can be used to compute ray trajectories in the tapered regions and have devised an expression (similar to the critical angle in total specular reflection) for the maximum acceptance angle that happens to be ∼42° for our structure.


Journal ArticleDOI
J. J. Hupert1
TL;DR: In this paper, the role of evanescent waves and fields in microwave waveguides is discussed in the context of oscillatory natural modes determining the character of propagating fields, and the flowgraph technique and unit real function representation are used to discuss the interdependence of incident and reflected waves in various locations in multilayered structures.
Abstract: Evanescent waves and fields play an important role in microwaves, quantum mechanics, optics and elastic waves. Because electromagnetic waves in waveguides have dispersion characteristics similar to those of a unidimensional de Broglie wave, there is a close analogy between quantum mechanical tunneling and the transition through an attenuating sector of a waveguide. Microwave “evanescent mode” filters, quantummechanical tunneling resonance and optical frustrated total internal reflection filters are compared in light of this analogy. The flowgraph technique and “unit real” function representation are shown to be effective in discussing the interdependence of incident and reflected waves in various locations in multilayered structures. In electrognetic and elastic waves, the role of evanescent waves is significant in the case of incident beams of limited extent. The role of equivalent circuits of transverse resonance is discussed in the context of oscillatory natural modes determining the character of propagating fields.

Journal ArticleDOI
TL;DR: A new method is described for measuring the optical attenuation of bulk glasses in the wavelength range of 0.4-1.1 microm, and two different kinds of commercial glasses, fused quartz (Ultrasil) and synthetic vitreous silica (Suprasil W1), are reported and discussed.
Abstract: For the production of fiber waveguides suitable for optical communications cables, glasses with extremely low attenuation are required. A new method is described for measuring the optical attenuation of bulk glasses in the wavelength range of 0.4–1.1 μm. Using a quartz halogen source with highly stabilized radiation power, a linearly polarized, monochromatic, collimated beam was produced, passing the sample at the Brewster angle. Transmission loss, residual reflection, and surface scattering were measured by low-noise photodiodes and integrating digital voltmeters. A stability of 10−5 and a resolution of 10−5 or better were achieved. Results for two different kinds of commercial glasses, fused quartz (Ultrasil) and synthetic vitreous silica (Suprasil W1), are reported and discussed.

Journal ArticleDOI
TL;DR: In this paper, a computer program was devised for obtaining optimum values of the six parameters that define the index profiles, given a sufficient number and distribution of mode-angle measurements, illustrating the generality of the parameter-optimization procedure.
Abstract: Heterostructure GaAs–AlxGa1−xAs–GaAs waveguides for 10.6 μm wavelength grown by liquid-phase epitaxy have a linear variation of dielectric constant in their substrates. On the basis of their mode equation, a computer program was devised for obtaining optimum values of the six parameters that define the index profiles, given a sufficient number and distribution of mode-angle measurements. The optimized parameters agreed well with the measured values for a variety of waveguides, illustrating the generality of the parameter-optimization procedure. Two types of leaky modes were observed, whose effective index β/k is less than the seed index, (1) Lummer–Gehrcke modes that are incompletely reflected at the substrate–seed interface and (2) low-loss totally reflected modes whose evanescent fields radiate into high-index seeds.

Journal ArticleDOI
TL;DR: In this article, the authors made a study of electro-optic total-internal-reflection diffraction device modulator electroding and found that a reflection phase mismatch of 16 degrees adds to insertion loss by 2%, but at 28 degrees this addition rises to 6%.
Abstract: A study is made of electro-optic total-internal-reflection diffraction device modulator electroding. This can cause reflection phase inequalities which can reduce transmission (zero order) and degrade the extinction ratio. Al, Cu, Au, and Cr electrodes are considered and Al/Cr appears the optimum choice for LiNbO3 devices. A practical LiNbO3/Cr device realization is shown to exhibit a 0.6% insertion loss contribution due to this effect and agrees with theory. Analysis shows that a reflection phase mismatch of 16 degrees adds to insertion loss by 2%, but at 28 degrees (mismatch) this addition rises to 6%. An extinction ratio >100:1 was noted.