Recent developments in production of glass integrated optical circuits are reviewed. Components realized by the two major waveguide technologies, i.e. ion exchange in glass and silica on silicon, are discussed. A number of applications for glass integrated optics devices are mentioned. The advancement of fiber attachment and device packaging is also reviewed.

The flexure-beam micromirror device (FBMD) developed by Texas Instruments, Inc., is presently being considered for use in communication and imaging systems. This device consists of thousands of individually addressable micromirror elements with phase-mostly responses, greater than 70% active area, and response times of 10 microseconds. Accurate determination of individual mirror element amplitude and phase responses versus address voltage is important for understanding the effect this device will have in the various applications. an experimental setup based on a laser microscopic interferometric technique was used to precisely map the surface displacement of individual mirror elements as a function of address voltage. The test structure consisted of an 8 X 8 array of 25 X 25 micrometers square flexure-beam elements. A phase response of greater than 2(pi) radians at a wavelength of 632.8 nm was observed for address voltages ranging from 0 to 5.8 V. The phase versus voltage relationship is shown to be nonlinear.

A novel coupling structure between antiresonant reflecting optical waveguides (ARROW's) is proposed. In this structure, the separation thickness between dual ARROW's is chosen for destructive interference in the decoupling section, and changed to an efficiently coupling value in the coupling section. The coupling length is about 710 micrometers for InP/InGaAsP materials, which is very promising for practical applications.

The grating is divided to a cascade of unit cells. For each of the unit cells a transmission matrix is derived. For analyzing the step junctions in a unit cell physical optics approximation is used. Transmission matrix of the entire grating is generated by multiplying the transmission matrix for each unit cell.

We report a novel surface-micromachined micro-optical bench (MOB) technology which enables us to monolithically integrate 'flipped-up' free-space optical elements with micro-positioners and micro- actuators. This technology allows complete optical systems be implemented on a single Si chip using IC-like microfabrication processes. We have, for the first time, successfully fabricated micro-Fresnel lenses, mirrors, beam-splitters, gratings, and precision optical mounts, as well as rotational stages and other micro- positioners. Self-aligned hybrid integration with edge-emitting lasers and vertical cavity surface-emitting lasers (VCSEL) are also demonstrated for the first time. The MOB technology could significantly reduce the size, weight, and cost of most optical systems, and has a significant impact on optical switching, optical data storage, optoelectronic packaging.

It has previously been shown that bulk silicon micromachining using a dissolved wafer process with an impurity based etch stop can be used to fabricate structures with variable thickness, high (thickness-to- width) aspect ratios, and overhanging features, as well as structures with multiple stacked levels. This technology has been further extended in the development of silicon micromachined thermal profilers (SMTPs). The SMTP consists of a polysilicon-gold thermocouple located at the tip of a probe shank that overhangs the edge of the substrate. The probe shank is suspended by flexible beams, and can be electrostatically excited into motion by comb drives. A polysilicon heater is built into the base of the shank to provide a thermal bias. As the thermocouple is scanned across a sample, the varying proximity and temperature of features on the sample surface can be mapped as a function of position, providing high resolution topographic and thermographic information. The same principle can also be used in photothermal absorption spectroscopy, microelectronic metrology, and microflow measurements. Advanced versions of the SMTP suspend the thermocouple on a dielectric diaphragm for improved thermal isolation, and replace it with a thermopile for a larger readout signal. Devices have been fabricated using an IC-compatible, 8 mask, single-sided process that has general applicability beyond the SMTP. Preliminary data from test scans is presented.

This paper describes the fabrication process and preliminary experimental results of a polygon mirror microscanner. The fabrication process is established by the integration of polysilicon surface micromachining and electroless plating of nickel. The scanner structures studied are similar to conventional mechanical polygon mirror scanners but utilize micromotors with diameters up to one millimeter. The micromotors are fabricated by polysilicon surface micromachining. The optical elements are hexagonal nickel reflectors up to 20 micrometers tall fabricated by selective electroless plating of nickel on the rotor of the micromotor. Successful fabrication of the micromotors with nickel reflectors on the motor has been demonstrated. Optical measurements have been performed at visible wavelength (633 nm) using multi-mode optical fibers for the source illumination positioned roughly in the plane of the substrate. The scanned, reflected radiation was detected via scattering from the substrate and by a television camera in the plane of the substrate.

Near field scanning optical microscopy (NSOM) has been used to investigate the guided mode intensity distribution in optical channel waveguides, phase-matched directional couplers, and symmetric Y- junctions. A near field measurement of the lateral guided mode intensity profile was performed across the optical channel waveguide, and compared with model calculations. The near field guided mode intensity profiles above the waveguides were measured as a function of distance along both a directional coupler and a Y-junction, providing a near field view of the spatial evolution of optical power in these structures.

GaAs-based micromachining is a very attractive technique for integrating mechanical structures and active optical devices such as laser diodes and photodiodes. For the monolithic integration of micromechanical parts onto laser diode wafers, the compatibility to a laser diode fabrication process is essential. Our micromachining technique features three major processes of epitaxial growth (MOVPE) for both structural and sacrificial layers, reactive dry-etching by chlorine for high-aspect, three-dimensional structures, and selective wet-etching by peroxide/ammonium hydroxide solution to release the moving parts. These processes are compatible with laser fabrication, so a cantilever beam structure can be fabricated at the same time as a laser diode structure. Furthermore, a single-crystal epitaxial layer has little residual stress, so precise microstructures can be obtained without significant deformation. We fabricated a microbeam resonator sensor composed of two laser diodes, a photodiode, and a micro- cantilever beam with an area of 400 micrometers X 700 micrometers . the cantilever beam is excited by an intensity modulated laser beam from an integrated excitation laser diode, and the vibration signal is detected by a couple cavity laser diode and photodiode.

A fiber-optic temperature sensor used a polysilicon thin-film Fabry- Perot etalon. An amorphous silicon film is sputter deposited directly onto a fiber end, crystallized using an argon ion laser, and then encapsulated by two sputter deposited films. Since silicon's refractive index is strongly temperature dependent, the location of one of the minima in the etalon's spectral reflectance can be used to determine the sensed temperature. The annealing process is a critical step in producing a stable sensor. This process is characterized, and the results of long-term sensor stability tests are presented.

Using the weak guidance approximation and the point matching technique, a thorough analysis has been carried out of the propagation characteristics of a dielectric pentagonal waveguide cladded by a perfectly conducting substance.

Substrate and waveguide cross talk models are presented for CMOS smart detectors arrays. A test chip of linear arrays using both p⁺n and n⁺p detectors has been designed and fabricated for characterization of substrate and waveguide cross talk. It is shown that both the substrate and waveguide models agree well with the measured cross talk. Techniques for reducing cross talk in CMOS detector arrays are also presented.

Ferroelectric thin films have been integrated with silicon-based microelectromechanical systems, commonly called MEMS. Several thin films of the PZT family have been used in the formation of both microsensors and microactuators in processes compatible with silicon nitride, surface-micromachined, membranes and analog CMOS technology. Back-end micromachining of MEMS structures based on PZT-type electroceramic thin films is described. Several ferroelectric MEMS examples are described including (1) cantilever beam micro- accelerometer, (2) acoustic pressure sensor, (3) uncooled pyroelectric infrared imaging array, (4) integrated acoustic sensor, (5) micro- positioner, and (6) simple cantilever flap actuators. Major issues of merging technologies with ferroelectric thin films with microelectromechanical structures and on-chip electronics are described.

Immense computational power of today's processors cannot be fully utilized unless appropriate sensors and actuators are developed to link them with the outside world. A method is presented here to compare different sensors with each other and to evaluate their relative merits. Sensors are decomposed into two essential building blocks: a sensor shell and a sensing mean. Eleven different types of sensors, having the same sensing shells, are analyzed and compared to each other.

An electrically passive optical pressure sensor has been fabricated which uses a integrated-optical Y-junction ring resonator to measure the strain induced in a micromachined silicon diaphragm. A silicon substrate is etched from the side opposite the silicon oxynitride optical waveguides to produce a rectangular diaphragm whose long edge lies underneath a straight section in the ring. Pressure-induced changes in the resonant frequency of the ring are measured using a frequency swept laser diode. A linear response to pressure is observed for the TM mode with a sensitivity of 0.0094 rad/kPa. The transmissivity function of the resonator is derived and compared with measured response. This pressure sensor is rugged, amenable to batch fabrication, and it provides a link insensitive readout.

There is an increasing interest in using an integrated optical waveguide as a displacement or pressure sensor. This paper provides a theoretical analysis of 3-D channel waveguides subjected to deformation. The analysis is rather general and can be extended to many practical channel waveguides. The motivation for this paper is to provide the designers of integrated optical sensors simple formulas to evaluate designs and material systems. Our analysis begins with a straight channel guide having an isotropic refractive index. In Section I, we consider the wave solutions to this channel waveguide using the Marcatili method. We give all the pertinent equations for performing first order calculations.

Channel waveguides are increasingly used as transmission media, filter and coupler, periodic structures and active components. Very recently integration of channel waveguides with microstructure sensors has been proposed. This new application is especially concerned with the behavior of waveguide bending and deformations as well as it's propagation characteristics in straight sections. A number of numerical methods such as FD-TD2, BPM3 and mode matching have been used for analyzing propagation characteristics and discontinuties of these waveguides. These methods are generally (numerically) slow and require a vast amount of computer resources, and therefore are not suitable for design/optimization purposes. Recently a semi-analytical and insightful method based on physical optics for solving discontinuity problems has been proposed4, In which the ray representation of the propagating modes is combined with the equivalent source formulation for a 2-D dielectric waveguide. Here we extend this approach to a 3-D dielectric channel waveguide. This extension requires (plane wave) ray representation of the modal fields in a 3-D channel waveguide. We develop such representation by using Marcatili's approximate field expressions and dispersion relations for a dielectric channel waveguide. This ray picture is then used to determine the radiation from the bent sections.

in this paper , a new design method for geodesic lens , which has an analytic solution of rotational symmetry , is pro posed. Based on Fermat' s and Clairut' s principle , using the variational principle , referring to the general solution method of Toraldo and choosing a suitable rounded edge function , the expression of profile is obtained. This kind of analytic meridi an curve is convenient for design and fabrication. This type of geodesic lens is not only aberration-free , but also loss lower than the others , because it solves the problem of curvature radius R being zero (R =0) on the transition parallel circles, which causes the scattering losses tend infinite. The test result is coincident with the theoretical predicting value perfectly.

We report on the use of media on the base of chalcogenide vitreous semiconductors (ChVS) to fabricate periodical structures for integrated and diffractive optics. Most of attention is devoted to the original properties of such media, which are based on two effects: photodoping and photostimulated solubility changes of ChVS layers. The composition of ChVS was mostly from As-S-Se line. The lightsensitivity properties (including characteristic curves) of ChVS layers and ChVS - Ag systems are presented. The results of the direct recording of periodical structures with the help of sharply focused laser irradiation on ChVs - Ag systems and ChVS layers are discussed. It is shown that with the help of laser lithography on the ChVS-Ag systems it is possible to produce narrow lines, the width of which is substantially narrower that the exposure beam halfwidth (similar to the reported earlier by us effect on ChVS layers). The both cases are explained by the peculiarities of the characteristic curves of the given inorganic resists and lightsensitivity dependence from the temperature. The 'selffocusing' effects in such media enables to produce lines of up to 0.17 micrometers width on recording wavelength (lambda) equals 476 nm. Increased resolution capability enables to produce the asymmetrical profiles by using the direct recording with the help of sawtooth-like exposure distribution. The possibility of image transfer into relief forming layer or substrate with the help of wet or dry etching is shown.

A commercially available broadband (20 GHz) Titanium indiffused Lithium Niobate traveling wave Mach-Zehnder interferometer was evaluated for its wavelength sensitivity. The electrooptic transfer characteristic was measured over the wavelength range between 1500 nm and 1565 nm. Variations of the extinction ratio, intrinsic phase bias and the halfwave voltage were evaluated. Measurements confirmed that the halfwave voltage increases linearly with wavelength and the intrinsic phase bias varies inversely as predicted by theoretical analysis. The extinction ratio was found to remain approximately constant.

The waveguide dichroic coupler in lithium niobate is used to couple 1.55 micrometers signal and 0.98 micrometers pumping source into Er-doped fiber simultaneously. In order to improve the function of an Er-doped fiber amplifier, a Ti/Mg double diffusion method is employed to increase the coupling efficiency for the dichroic coupler to the Er-doped fiber in the endface configuration. The configuration of dichroic coupler has a buried guiding core and high coupling coefficient. Those desired functions can be achieved by optimizing the design of the relative fabrication parameters.

An integrated optical device for a two component, dual beam multiplexed laser Doppler anemometer has been realized. The proton exchange and the subsequent annealing procedure in MgO:LiNbO₃ yield waveguide structures with completely restored electro-optic effect, low waveguide loss, high coupling efficiency to fibers, and an increased optical damage threshold. In the device for the laser Doppler anemometry the functions of spatial filter, polarizer, beamsplitter and electro-optic modulators are integrated on a single chip. The present paper investigates the use of a specific integrated optical device as a next phase of evolution in laser Doppler anemometry.

The design and performance of an optically linearized modulator for AM CATV applications is described. The device is based on a cascade coupling of interferometric waveguide phase modulators operating at 1550 nm wavelength. A substantial number of these modulators have been deployed in CATV systems.

Photorefractive Fe:LiNbO3 waveguides have been fabricated from Fe: LiNbO3 substrates by proton-exchange. Holographic method was used to measure the light-induce refractive index change in the waveguides and the result mdicated that the waveguides have higher sensitivity and larger index change than pure LiNbO3 waveguides. Optical amplification has been achieved through two-wave mixing and amplification rate up to 200 was obtained.

The relationship between deformations of crystal lattice and extraordinary refractive index change has been experimentally determined for proton-exchanged lithium niobate waveguides. It has been shown that the strains induces by the substrate strongly modifies the phase diagram obtained for powders. Depending on exchange and annealing conditions and crystal cuts, at least the six phases x -, 13-, -, 5-, ( and 'Ti - HxL:L1-NbO3 can exist in single crystal layers. The regularities of proton exchange in lithium niobate crystals under different exchange and annealing conditions are studied and various specific features are explained.

A modified conformal mapping method for analyzing traveling-wave modulators in LiNbO3 crystal is presented. In order to improve performances of LiNbO3 electrooptic devices, rigorous studies on the characteristic impedance and the effective dielectric constant are required. This analytical model is suitable for considering the aforementioned electrical properties for LiNbO3 traveling-wave modulators with finite thickness electrodes and a buffer layer. Numerical results are comparied with the available data derived from the mode matching method.

A model describing the mechanism of solid-state film diffusion into oxide substrates was developed and shown to accurately predict the dopant concentration profiles1 . The model coupled oxidation of the dopant at the metal-substrate interface with field assisted diffusion of the resulting metal ions into the substrate. The model, an adequate description of the process once initiated, could not explain how the diffusion process starts nor the experimental behavior observed at low electric fields (< 25 V/cm). This current work investigates the initiation of solid-state film ion exchange (Ag+ Na+) in glass substrates. In this paper we establish the fundamental space charge origin of the initiation process and show how this space charge gives rise to the Mott potential necessary for initiating the oxidation of the metal dopant. A one-dimensional, charge transport model is presented considering the development of space-charge effects in glass having two charge-blocking electrodes. The model results indicate that the rate limiting step for initiating Ag+ diffusion in glass is the motion of oxygen ions towards the silver anode. The predictions of this model compare favorably with the "dead times" observed in the current vs. time curves during ion-exchange. The dead time corresponds to the accumulation oxygen ions at the metal-glass interface and consequently, a period of negligible diffusion of silver into the glass. The absence of silver diffusion during this period was confirmed by analyzing the surface composition of the glass using Rutherford backscattering analysis (RBS).

Circuit model for the quantum well (QW) laser diode has been developed from the rate equations . The model L simulated using the circuit simulation program SPICE2 and validated by comparing dc and transient analysis with PubIShed data. Further, the model in conjunctionwith the optical fiber and photodetectormodel constitutingan optical link has been simulated. Circuit models for gain switched OW lasers are developed and picosecond pulses of 7 and 2 pSCC F\VHM corresponding to the second and third quantised state transitions, respectively were observed by simulating the models. A remarkable reduclion in the output pulsewidth that is observed for the third quantised level transitions demonstrates the significance of higher subband transitions for the generation of ultra short pulses. Effects of cavity U:nth and number of wells on the output puLse shape were also analyzed.

A new method using vacuum-drying is demonstrated for producing graded index (GRIN) profiles on type-A photolime gel-based polymer waveguides. Vacuum-drying allows optical waveguides to be built on higher index of refraction substrates without intermediate lower index cladding layers. The waveguide loss and graded index profiles were compared for vacuum-dried and alcohol-dried samples.

This paper describes a channel waveguide beam splitter (CWBS) in which a single laser beam can be split into many beams using glass stripe waveguides and localized surface relief gratings. The grating element situated on top of individual 90 degree(s) T-branches couples a fraction of the backbone light down a side channel and acts as a miniature mode converter. Single-mode TE light in the backbone is converted into single-mode TM light in the side channel. The laser wavelength used in these experiments was 830 nm. Each individual grating was only a few microns in length and so the grating acceptance exhibited a large bandwidth. The total excess loss coupling the input waveguide optical power partially into 100 waveguide branches was only 0.25 dB.

We report here a new waveguide electrooptic grating coupler modulator based on a tooth-shaped modulation electrode structure and a single straight channel waveguide on an electrooptic substrate. An electrooptically-induced grating on the channel waveguide couples the propagating single or multimode lights into the substrate, and thus achieves intensity modulation of the guided modes. Both single-mode and multimode operations are possible. Preliminary experiments have demonstrated the effect of modulation on a proton exchanged LiNbO₃ waveguide device. Modulation on other electrooptic waveguides are expected.

Excitation of leaky optical waves in optical waveguides on lithium niobate while total internal reflection of light beam with corresponding polarization from their surfaces has been investigated. The "mirror' configuration of waveguide operating elements on the ground of electrooptic and photorefractive interactions with leaky wave participation has been proposed and some results of their experimental investigations are presented. Key words: Optical waveguide, leaky waves, electrooptical effect, photorefractive effect, light modulation.

Zinc-boron-silicate glass doped with cadmium sulfide-selenide was synthesized, and arising and growth of Cd-S-Se microcrystals in the glass matrix under annealing was studied. The annealing dependant shift of absorption edge of the glass samples was demonstrated. Transmission electron microscopy proved that quantum confinement effect was an origin of the shifts. Growth of the microcrystals was followed by increase of their dispersion. Also the growth led to transformation of structure of the microcrystals from cubical to hexagonal. Cesium-potassium ion exchange in the SDG was applied to optical waveguides formation. Differences of the alkaline ion profiles in the glass samples annealed differently were observed.

We introduce a new type of planar optical interconnect; the transverse holographic waveguides. We demonstrated that a simple N X 1 connection may be achieved with loaded multimode waveguides.

Integrated optic Mach-Zehnder modulator array (IOMZMA) devices have been investigated for application to an optical board-to-board interconnect system. Two types of four-unit IOMZMA devices have been developed using X-cut LiNbO₃ crystal as the modulator substrate, with the modulator-to-modulator separations matched to an output graded-index (GRIN) lens array or commercial ribbon fibers. The design parameters, fabrication methods, procedures, and measurement results are presented. A preliminary application of the IOMZMA device to an optical interconnection system is demonstrated.

an electrooptic polymer with chlorophenol red dye and type-A photolime gel was demonstrated. The electrooptic coefficient (gamma) ₃₃ in the direction of the poling field was measured to be 28 pm/V. Chlorophenol red in polymer showed a 1/e relaxation time constant of 820 hours, which is more stable than other dye demonstrated previously to be electrooptic in the same polymer.

The design and fabrication of a surface plasmon resonance electro- optic polymer light modulator in a bulk format is discussed. Initial experimental results are presented which demonstrate up to 18.5% modulation for a surface plasmon modulator constructed on the base of a SF-59 window using a silver/polymer/silver configuration. A theoretical model for the miniaturization of this device into an integrated optical configuration is presented. The potential benefits and obstacles associated with fabricating this device in an integrated configuration are discussed.

The main idea of the present report is to demonstrate the possibilities of various types of interactions for light modulation and waveguide probing. The electro-optical and thermo-optical modulation in the Ti:LiTaO₃ Mach-Zehnder interferometer and acousto-optical modulation in Ti:LiNbO₃ interferometer is reported. The colinear acoustooptic diffraction is applied for guided mode effective refractive index measurements.