Abstract: A method of optical analyses of a test sample which comprises a sample material with light-absorbing, scattering, fluorescent, phosphorescent or luminescent properties, which sample is partly in a liquid phase and partly bound to an adjacent solid surface, to discriminate the respective parts of said sample material which are located in the liquid and bound to said solid surface: comprising the steps of providing as said solid surface a surface of transparent solid optical waveguide, and measuring light from the sample material bound to said solid surface that has passed into and through said transparent solid optical waveguide with total internal reflections and emerged from said waveguide at an angle that deviates from the optical axis of said waveguide by an angle appreciably less than alpha, where alpha = arcsin $(1,4)$(n22-n12) where n2 is the refractive index of the material of the waveguide and n1 is the refractive index of the adjacent liquid, and excluding from said measurement substantially all light that has emerged from said waveguide at an angle that deviates from said optical axis by alpha or more.

Abstract: A hybrid optical integrated circuit having a high-silica glass optical waveguide formed on a silicon substrate, an optical fiber and an optical device coupled optically to the optical waveguide, and an optical fiber guide and an optical device guide on the substrate for aligning the optical fiber and the optical device at predetermining positions, respectively, relative to the optical waveguide. Islands carrying electrical conductors are disposed on the substrate. A first electrical conductor film is formed on the substrate. Second electrical conductor films are formed on the top surfaces of the optical waveguide, the optical fiber guide, the optical device guide and the islands and are electrically isolated from the first electrical conductor film. An electrical conductor member is provided to feed electric power from the first and second electric conductor films to the optical device which needs the power supply. The optical waveguide, the optical fiber guide, the optical device guide and the islands are formed from the same high-silica glass optical waveguide film. Alignment of various portions is facilitated when assembling the circuit. A high coupling efficiency is realized with a low cost.

Abstract: A comparison is presented between optical bistability in laser amplifiers and in passive Fabry-Perot cavities. The basis for comparison is afforded by a new analysis of optical amplifiers which encompasses the cases of passive refractive and absorptive bistability as special limiting cases. The results indicate that amplifiers have advantages of lower input intensity requirements (by a factor of 103) and reduced sensitivity to wavelength by comparison with passive cavities; experimental results indicate an input power of -30 dBm is required for active bistability. Facet coating requirements for active and passive optimum configurations are also discussed.

Abstract: Reflectivity of an antireflection-(AR) coated laser-diode (LD) facet is analyzed on the basis of a slab waveguide model and an angular spectrum approach. The reflectivities of single- and double-layer AR coatings on 1.55-μm GaInAsP/InP LD's are numerically calculated. Optimum film parameters, such as thickness and refractive index of single-layer AR coating films, are obtained as functions of the active layer thickness. A minimum reflectivity as low as 1 \times 10^{-4} was realized using refractive index controlled SiO x film as an AR coating for a 1.55-μm GaInAsP/InP buried-heterostructure (BH) LD.

Abstract: This paper presents are view of the numerical methods for the analysis of the homogeneous and inhomogeneons,isotropic and anisotropic, microwave and optical dielectric waveguides with arbitrarily-shaped cross sections.The characteristics of various methods are compared,and a set of qualittative criteria to guide the selection of an appropriate method for a given problem is proposed. The main approaches discussed are those of point matching, integral equations, finite difference, and finite element.

Abstract: The density of the energy that is conducted within a fiber-optic waveguide (12) is increased by means of an energy coupler (30, Figures 3 and 4) at the input end of the optical fiber (12). This energy coupler comprises a fused or ground lens (46) at the input end of a silica-based fiber (12). A second lens (47), preferably a plano-convex lens, focusses a large collimated laser beam to a point source (48). The lens (46) at the end of the fiber (12) is located at a distance greater than the focal length of the second lens (47), so as to receive light from the point source (48) and couple it into the fiber (12).

Abstract: The measurement of reflection from an open-ended waveguide is a simple and nondestructive technique for determining the dielectric properties of materials. A flange-mounted waveguide is considered, the flange being pressed on an unknown material which may be of finite or infinite thickness. The relationship linking the reflection coefficient to the dielectric properties is obtained from a theoretical analysis of the electromagnetic field in the vicinity of the aperture. The theory includes the effects of both cross polarization and higher order modes. An integral equation is obtained, the kernel of which is the dyadic Green function in each medium. The method of characteristic modes is used for the numerical computation. The theoretical results are in good agreement with experimental measurements. Futhermore, a simple and handy technique for data inversion is provided.

Abstract: By incorporating two quantum wells into a capillary waveguide, we have made the first MQW optical modulator with an on/off ratio of at least 10:1. Furthermore, this device was used to generate an optical pulse less than 100 ps long, the fastest to date with an MQW device.

Abstract: The fused single-mode tapered coupler is successfully modelled by assuming that the neck section of the coupler can be represented by a rectangular dielectric waveguide. Guidance is provided at the glass-to-air (or external medium) boundary and the cores are neglected. The mechanism of field detachment from the cores is outlined and the coupler characteristics are derived from the interference between the two lowest-order modes of the large waveguide.

Abstract: The planar-circuit approach to the analysis and design of microwave integrated circuits (MIC's), with specific reference to microstrip circuits, is reviewed. The planar approach overcomes the limitations inherent to the more conventional transmission-line approach. As the operating frequency is increased and/or Iow-impedence levels are required, in fact, the transverse dimensions of the circuit elements become comparable with the wavelength and/or the longitudinal dimensions. In such cases, one-dimensional analyses give inaccurate or even erroneous results. The analysis of planar elements is formulated in terms of an N-port circuit and results in a generalized impedance-matrix description. Analysis techniques for simple geometries, such as the resonant mode expansion, and for more complicated planar configurations, such as the segmentation method, are discussed along with planar models for accounting for fringing fields effects and radiation loss.

Abstract: The fabrication and optical properties of reactive ion-etched, totally reflecting mirrors for single-mode GaAs rib waveguides are described. Low loss and orientation independance make the device useful in integrated optics, in order to increase packing density and to facilitate waveguide to fiber coupling. Results of displacement sensitivity calculations are also shown.

Abstract: A beam propagation method is employed to analyze the characteristics of crossed optical waveguides and related switches, based on such crossed waveguides. The complex coupling properties of passive crossings are highlighted and general design guidelines for passive devices as well as for switches are given.

Abstract: The transition waveguide to shielded and dielectric image guide is analyzed by the rigorous hybrid-mode field expansion technique where higher order mode coupling effects are taken into account directly, also below the corresponding cutoff frequency. The solution of the related eigenvalue problem includes waves with a complex propagation constant although the guide is assumed to be lossless. Calculated diagrams of the propagation constant as a function of frequency, as well as of the permittivity, illustrate the complicated mode conversion between evanescent modes, complex waves, backward waves, and propagating waves. For the three-dimensional scattering problem, the calculated magnitude of the input reflection coefficient agrees well with measurements, whereas the transmission-line theory applied to this structure leads to wrong results.

Abstract: A polarization integral equation is advanced for use in the conceptual and numerical analysis of a broad class of integrated dielectric waveguiding systems. The equation is applied to axially uniform waveguides, in which case the axial integral becomes convolutional in nature, prompting a Fourier transform on that variable. Inversion of the transformed guiding region field, aided by complex analysis, allows identification of two components of that field the surface-wave modes and the radiation field. These are found in terms of the sources exciting the system, leading to a new formulation for the excitation of such waveguides. Analysis of the behavior of the kernel of the transformed integral equation in the complex plane leads to a general criterion for surface-wave leakage from the guiding region. Numerical results for the propagation characteristics of step- and the graded-index rectangular strip and rib waveguides are obtained from the integral equation by application of the method of moments and by a quasi-closed-form solution technique. These results are compared to those of other formulations. Further application of the integral equation is discussed, and several promising areas for further study are identified.

Abstract: We report the observation of enhanced fluorescence from molecules deposited on the surface of an optical waveguide structure. We attribute the enhancement to the near-field interaction between the Rhodamine B molecules and the waveguide’s modal fields. The process does not require the use of prism or grating couplers and can give rise to an enhancement factor in excess of 2 orders of magnitude.

Abstract: A waveguide-to-coax-to-microstrip transition includes a rectangular waveguide portion having a ridged impedance transformer attached to the lower wide wall. The waveguide portion is closed off by a conductive wall through an aperture in which the center conductor of a coaxial transmission-line passes. A ridge extension isolated from all four walls of the rectangular waveguide couples the ridge to the center-conductor of the coax. For broadbanding, a glass plate is located between the ridge extension and the upper wide wall. The strip conductor of a microstrip transmission-line is connected to the center conductor of the coaxial transmission-line. The plane of the dielectric plate of the microstrip may be oriented parallel to the narrow wall of the rectangular waveguide to achieve high packing density.

Abstract: Single‐mode planar waveguide microlenses and microlens arrays in LiNbO3 have been fabricated using a combination of titanium diffusion and proton exchange processes. The lenses have demonstrated properties such as very short focal length, micron focal spot size, and large angular field of view that are desirable for applications in integrated and fiber‐optic signal processing and computing as well as communication systems.

Abstract: A resonant waveguide cavity, preferably a loop, is fabricated from an active material doped host glass and includes a wavelength dispersive lateral coupling designed to preferentially support wavelengths in a selected bandwidth. Pumping light is provided to excite the active material so that the supported wavelengths stimulate in phase emission to increase their amplitude with the amplified signal presented to an output fiber. Where a signal generator is desired, the pumping light can be used to drive the resonant cavity into oscillation to provide a CW output at one of the cavity supported wavelengths.

Abstract: A device for processing optical data comprising: an optical waveguide formed on a substrate, a light source for the laser beam to be admitted into the waveguide, lens means provided on the waveguide for causing the beam propagating through the waveguide to emerge obliquely upward and focusing the emergent beam two-dimensionally, means for receiving the beam reflected obliquely from above, a base provided with the laser light source, the substrate and the light receiving means, a focusing drive mechanism for adjusting the position of the base upward or downward, and a tracking drive mechanism for adjusting the position of the base laterally.

Abstract: In this paper we report a simple method of measuring mode propagation losses of integrated optical waveguides with small scattering. The basic technique, reported previously, uses a microcomputer-assisted video camera; here we have improved our observation scheme by coating the optical waveguide with a thin film of fluorescent dye (Nile Blue A perchlorate) thus permitting observation of the optical fields. The Nile Blue A perchlorate absorbs light centered at 0.63 μm and emits light centered at 0.69 μm. We have measured a mode propagation loss of the order of 0.1 dB/cm of a potassium ion-exchanged glass waveguide and confirmed the damped oscillatory behavior of the attenuation vs a slightly lossy thin-film thickness curve for the ion-exchanged waveguide coating with an indium tin oxide film.

Abstract: Fluorescence enhancement is obtained using an optical waveguide consisting essentially of films of fluorescent molecules and of conductive material separated by a dielectric layer. The enhancement is believed to be due to the near field interaction between the molecules of the fluorescent material and the waveguide modal fields. No special couplers (prisms or gratings) are needed between the fluorescent material and the waveguide. The enhancement factor is in excess of two orders of magnitude over fluorescence from the material without the use of the waveguide.

Abstract: We report on coupling arrays of SM fibers in silicon V - grooves to waveguides. Arrays with up to 12 fibers have been permanently attached to waveguides with an average excess loss of 0.3 dB per interface. We discuss a subtle, heretofore unreported effect of polarization on fiber-waveguide insertion loss and we describe the first measurements of waveguide-mode position as a function of polarization. In general, the modes of a Ti:LiNbO 3 waveguide peak at different positions. This results in different optimum positions for coupling and thus leads to an unavoidable excess loss when attaching fibers. For low-loss waveguides, we predict a minimum excess loss of 0.25 dB per interface.

Abstract: To realize an optical integrated circuit, various losses in the semiconductor waveguide such as absorption loss, waveguide loss, bending loss, and coupling loss, have to be minimized. Theoretical and experimental considerations for the reduction of these losses have been presented. A propagation loss of less than 0.5 dB/cm has been observed for a well-designed GaAs ridge waveguide. Moreover its coupling loss with a polarization-maintaining optical fiber decreased below 1.5 dB.

Abstract: This letter describes a GaAs/AlGaAs quantum well (QW) waveguide-type optical modulator utilizing an electric field effect on two-dimensional exciton absorption. The waveguide modulator has the same structure as QW laser diodes, and is therefore suitable for monolithic integration with a laser diode. Optical modulation was measured up to 1 Gbit/s at a driving voltage as low as 1.4 V. The 3 dB-down modulation rate was 900 Mbit/s, but higher speed operation is expected.

Abstract: An optical waveguide path and an optical branch path branching from the waveguide path are formed in an optical material which is variable in refractive index with the variation of temperature. A heat generator is provided in the vicinity of the branching portion of the waveguide path. The heat of the generator produces in the optical material a temperature gradient in a direction parallel with a plane including the waveguide path and the branch path. The temperature gradient gives the optical material a temperature gradient, by which a light beam propagating through the waveguide path is deflected for switching.

Abstract: Because of the large variety of materials and material forms available, organic materials are attractive candidates for ultrafast nonlinear optical signal processing systems based on the intensity-dependent index of refraction, i.e., the change of index of refraction with a change in applied optical intensity. As an example, we consider an organic polymeric system, the polydi-acetylenes. Through molecular engineering (organic synthesis and Langmuir-Blodgett film growth combined with monolayer deposition techniques), the polydiacetylene was prepared in the technologically important format of a planar waveguide on a grating. By measuring the change in the angle that the incident laser radiation couples into the guided-wave mode (via the grating) with the change in intensity of the laser radiation, we determined the intensity-dependent index of refraction to be 10-6 (MW/cm2)-1 in the transparent region of the material. Implications of this reseach for future work related to signal processing applications are discussed.

Abstract: Disclosed is an improved fiber optic sensor of the type in which a fiber optic waveguide component of the sensor is configured to be responsive to an external parameter such that curvature of the fiber optic waveguide is altered in response to forces induced by changes in the external parameter being sensed. The alteration of the curvature of the fiber optic waveguide causes variations in the intensity of light passing therethrough, these variations being indicative of the state of the external parameter. The improvement comprises coating material covering the exterior portion of the fiber optic waveguide, the coating material having an expansion coefficient and thickness such that distortion of the fiber optic waveguide caused by thermally induced stresses between the coating material and the glass fiber is substantially eliminated. Also disclosed is a support member for supporting the curved fiber optic waveguide, the support member and fiber optic waveguide being configured and arranged to minimize the effects of thermal stress tending to separate the waveguide from the support member.

Abstract: PURPOSE:To obtain an optical multiplexer and demultiplexer which is small in size and has a good extinction ratio and S/N ratio by setting the thickness, etc. of the optical waveguide layer parts positioned on both sides of a directional coupler in such a manner that the light of one wavelength transfers thoroughly from one optical waveguide to the other waveguide and that the light of the other wavelength propagates hardly in the optical waveguides. CONSTITUTION:The optical waveguide layer 4 and ridge type optical waveguides 1, 2 are provided by using a material having a high refractive index on a substrate 5 consisting of GaAs, etc. The thickness of the optical waveguide layer is so set that the thickness ta in the region part A positioned on both sides of the ridge type optical waveguides 1 and 2 and the film thickness te in the region part B positioned between the waveguides 1 and 2 differ from each other. The optical waveguides and the optical waveguide layer are so formed that the propagation characteristics thereof vary with the light of the prescribed wavelength and the light of the other wavelength. The height (h), width W and space (d) of the ridges are so set that the light of the prescribed wavelength are thoroughly coupled in the coupling section.