Low loss proton-exchanged optical waveguides using phosphoric acid exhibit properties which are different from those using benzoic acid. A maximum surface index increase of 0. 145 was measured for z-cut substrate at O. 633j. m and the index profile could be accurately modelled by a polynomial expression. This paper will review the development of proton-exchanged waveguides and devices using this acid.

Planar optical waveguides were fabricated using an electric field-assisted potassium ion-exchange in soda-lime glass substrates. Mode index measurements were made for the purpose of establishing formulas for the effective diffusion constant guide depth and refractive index change given the electric field the diffusion temperature and the time. The index profile could be accurately modeled by a modified Fermi function with significant improvement over the step-index model. The potassium ion concentration profile was determined using a scanning electron microscope (SEM) technique which is then correlated to the numerical simulation of the ion-exchange fabrication process.

We report on proton-diffused channel waveguides on Y-cut LiNbO3 fabricated by using pure benzoic acid for proton exchange and a self-aligned Si02 cap for diffusion. They do not exhibit surface damage since the rate of initial proton exchange can be lowered due to the proton conserving property of a selfaligned Si02 cap. The electrooptic property of the waveguide is investigated by the cutoff modulation of a channel waveguide. The proton diffusion with a self-aligned Si02 cap is proved to render good Y-cut LiNbO3 channel waveguides.

Mode index measurements of slab waveguides fabricated by proton-exchange and annealed protonexchange in z-cut LINbO3 have been made. A Fermi function was found to accurately model the PE index profile resulting in a better agreement between the measured mode indices and the computed dispersion curves compared to the conventional step-index profile. In addition the effect of various fabrication parameters on the propagation characteristics of single mode annealed proton-exchanged waveguides is investigated in detail.

New results on " as-grown" and protonated lithium tantalate crystals are given. Special attention is paid to crystals having different stoichiometry. The proton exchange in X- and Z-cut substrates was processed in pure benzoic acid for different time intervals. Optical waveguide measurements and infrared absorption studies have been performed to study the incorporation of protons. Definite correlation between the lithium concentration of the original crystals and the refractive index change in the exchanged layers has been observed.

Radiation effects on MESFETs and HFETs used in the fabrication of GaAs integrated circuits of the 1.7 Gb/s system and the 880 Mb/s Metrabus light wave systems are discussed. These devices are used in the driver and preamps of the light wave bus systems. Results on the traps formed from electron radiation as well as gamma radiation results are presented. There was negligible shift in the V sub th values. No new traps were detected. The new structure and fabrication technique are argued to be more radiation resistant than the previously tested ones. Results of annealing experiments performed using MESFETs after they were irradiated are presented.

The dynamical properties of LiNbO3 switches were measured as a function of radiation. The devices are titanium indiffused delta beta switches. Measurements of the gamma radiation level using radiation monitors indicate a total dose of less than 100 rad for a 5-min gamma exposure. The dc levels attenuate for the unswitched case, but not to the same degree that the switched signals do. With pulsed beam, a pulsed attenuation of the signal is evident.

Integrated optical devices can be used for optical code generation, code recognition and time multiplexing/demultiplexing, using data streams with data rates exceeding 100 GB/s. In this paper, a new nonlinear all-optical device for parallel-to-serial conversion using waveguide second-harmonic generation is described. This device can be configured to perform time demultiplexing or code recognition in a way that requires no active devices operating at the data rate.

Some new features that can be accomplished by means of a specific design of integrated optical depressed index waveguides (DIWs) are discussed, with emphasis on its application in wavelength filtering and multi/demultiplexing. Design procedures for two-mode interference filters using three-mode DIW structures are also shown. The design of the refractive index depression and the sensitivity of the devices to fabrication defects are examined.

The analysis and design of a Fresnel microlens array are developed in order to couple a large incident guided beam into a channel waveguide array for performing optical computing and signal processing operations. The device includes a planar waveguide region constituted by an AlGaAs/AlGaAs/GaAs epitaxial layer structure, with appropriate Al title and thickness, allowing the propagation of both the TE and TM polarizations of the guided beam. The channel waveguide region can be obtained by the diffusion of zinc in the planar waveguide. Each Fresnel lens of the array is assumed to be of the graded thickness type, and it can be fabricated on an additional AlGaAs layer by zinc diffusion. The designed array exhibits good theoretical properties, including very short focal length and very small focal spot size. It also makes it possible to couple only one polarization of the incident planar wave, i.e., TM polarization. A detailed simulation of the electric field distribution in the focal plane of each lens is also performed.

An experimental directly modulated fiber-optic link assembled and optimized for L-band operation with near-zero RF insertion loss is presented. This was achieved by optimizing the critical coupling of light from the laser diode to a single-mode fiber and by applying reactive matching circuits to the laser and detector in order to minimize RF reflection losses. Microwave performance measurements are made on the fiber-optic-fed T/R module, in terms of noise figure, intermodulation distortion, and dynamic range, and compared with the module performance without the fiber-optic link. It is shown that careful attention to optical coupling and to the reactive matching of the optical laser and detector transducers can lead to a link gain of -1.8 dB at 1.3 GHz and a 150 MHz bandwidth. The 66.5 dB/MHz exp 2/3 spurious-free dynamic range exhibited by the present link in conjunction with a T/R module demonstrated the feasibility of employing fiber optics in many antenna-remoting optically-controlled phase arrays and optical microwave interconnect applications.

The design of an integrated sensing system including a Silicon photodiode and a thermal pyroelectric detector is presented. The influence of a thermal insulator between both detectors to provide a good sensitivity to the structure is discussed through a simple model accounting for heat absorption and heat loss characteristics of the structure. An experimental set up is finally descnbed and investigated to be transposed and adapted in a car to obstacle detection. I .

The paper investigates the dependence of spectral linewidth for temperature and modulation in distributed Bragg reflector laser diodes. The spectral linewidth was measured by the delayed self-heterodyne method. It is proven that a rise in temperature and modulation frequency and modulation depth enhance the spectral linewidth. It is confirmed that there is a close relationship between environmental change and spectral linewidth. The variation of normalized spectral linewidth (NSL) was 2.0 MHz*mW/deg at 25 C.

A coupled cavity Fabry-Perot silicon electro-optic modulator for X 3 and 1. 5 jun is proposed and analyzed. The modulator consists of alternated slabs with high (silicon) and low (Si02 or air) refractive iixlex arI can be realized by standard microelectronic technique. Varying the optical properties of the silicon slabs by carrier injection it is possible to modulate tl light intensity transmitted across the device. The small size and the low current values requiitd to drive it ai compatible with a small scale integration.

Because directional couplers involve channel waveguides which are very close to one another, transition regions to regions where channel waveguides are widely separated are utilized. The total length of a directional coupler and transition regions can be minimized for a particular degree of field confinement. Calculations presented for LiNbO3-, GaAlAs-, and SiO2/Si-based optical channel waveguides demonstrate the presence of a minimum total length corresponding to a particular degree of field confinement. The overall length at the minimum is shown to be significantly lower than for other values of field confinement allowing single-mode operation. This implies that either more devices can be integrated on a substrate or that less material is needed for an integrated optical circuit.

In this work is presented a new efficient and simple method, which allows the analysis and design of planar optical waveguides. This method links the desired performances of the optical waveguides with basic technological parameters. The first four charts of the method can easily be adapted for planar waveguides of arbitrary index profile. The last two charts were obtained experimentally and are valid for diffused Ti:LiNbO optical planar waveguides. The main optical parameters may be easily interrelated utilizing a personal computer or drawing simple vertical and horizontal lines on an abacus.

Results on using the integratedoptics elements in pickup heads for read! write systems are reported In the head for digital information an acoustooptics was used to tune the focus position of the focusing grating coup1erThe measurements were carried out in Ti:LiNbOwaveguide for two wavelength of guided wave. In the head for holographic information the optical planar system was fabricated using TIPEtechnique. Acoustooptics creates information beams and modulates the intensity of every beam. I .

Optical interconnections in the intrachip, chip-to-chip, and board-to-board scenarios are investigated. A universal polymer waveguide formation method is developed. Tunability from the step index to the graded index of the polymer film makes it possible to construct planar and channel waveguides on any substrate including semiconductors, conductors, and insulators. A polymer waveguide modulator based on a current injection method is further developed. Modulation depth as high as 36 dB is achieved with an injection density of 1.8 micro-A/sq micron. A microprism coupler (about 125 microns) with a coupling bandwidth higher than 200 nm is developed to solve the interface problems among different interconnection schemes. Using this concept, optical waves from a single-mode waveguide can be successfully coupled to a multimode fiber.

The formation of both passive and active optical waveguide structures in thin films of organic polymers by a direct one-step photochemical process is reported. A photochemical transformation changes the chemical composition of a polymer of dye/polymer mixture. The reaction modifies the absorption spectrum of the material and thus alters its index of refraction. This technique is used to create waveguide structures both by spatially-selected laser direct writing and contact mask exposure. It is demonstrated that passive and active waveguide structures can be delineated in thin films of organic polymers by photochemically altering the index of refraction of the materials. The formation of single or multimode devices is possible using standard lithographic procedures which are suitable for mass production.

In this paper the performances of photonic interconnection networks are related to the characteristics of the switching elements. In order to design a photonic interconnection network the architecture has to be chosen on the basis of some topological and fault-tolerance characteristics. Moreover a very critical problem is the choice of the 2x2 switches. The Mach-Zehnder electrooptic modulator seems to offer a good compromise between the bandwidht requirements and the control voltage. In relation to these criteria a 4x4 omega network has been designed. It will be implemented on LiNbO3 crystal. Simulations have been carried out in order to foresee the performances of the whole structure and they show that the network will behave favourably in comparison with other well known switching arrays.

It is inevitable that Fibre Optics for data transmission and sensing will play a key role in future control systems for aerospace mobile platforms. It is important that the practical requirements for sensing/instrumentation in aerospace systems are well understood. Displacement sensing is a primary parameter and Wavelength Division Multiplex (WDM) digital optical encoding schemes offer a very attractive design solution.

Advanced aircraft engine propulsion systems must meet increasingly challenging performance requirements and endure more rigorous environmental conditions. The use of fiber optic technology provides much needed electromagnetic immunity without weight and cost penalties and also provides the other advantages of a fiber optic communication system. In this paper some of the application issues that arise due to the harsh operating environment are addressed.

This paper reports the first switching network compatible with multimode fibers. A one-to-many cascaded reconfigurable interconnection was built. A thin glass substrate was used as the guiding medium which provides not only higher coupling efficiency from multimode fiber to waveguide but also better tolerance of phase-matching conditions. Involvement of a total-internal-reflection hologram and multimode waveguide eliminates interface problems between fibers and waveguides. The DCG polymer graft has proven to be reliable from -180 C to +200 C. Survivability of such an electrooptic system in harsh environments is further ensured. LiNbO3 was chosen as the E-O material because of its stability at high temperatures (phase-transition temperature of more than 1000 C) and maturity of E-O device technology. Further theoretical calculation was conducted to provide the optimal interaction length and device capacitance.

Fiber optic technology is expected to be used in future advanced weapons platforms as well as commercial aerospace applications. Fiber optic waveguides will be used to transmit noise free high speed data between a multitude of computers as well as audio and video information to the flight crew. Passive optical sensors connected to control computers with optical fiber interconnects will serve both control and monitoring functions. Implementation of fiber optic technology has already begun. Both the military and NASA have several programs in place. A cooperative program called FOCSI (Fiber Optic Control System Integration) between NASA Lewis and the NAVY to build environmentally test and flight demonstrate sensor systems for propul sion and flight control systems is currently underway. Integrated Optical Circuits (IOC''s) are also being given serious consideration for use in advanced aircraft sys tems. IOC''s will result in miniaturization and localization of components to gener ate detect optical signals and process them for use by the control computers. In some complex systems IOC''s may be required to perform calculations optically if the technology is ready replacing some of the electronic systems used today. IOC''s are attractive because they will result in rugged components capable of withstanding severe environments in advanced aerospace vehicles. Manufacturing technology devel oped for microelectronic integrated circuits applied to IOC''s will result in cost effective manufacturing. This paper reviews the current FOCSI program and describes the role of IOC''s in FOCSI applications.

The application of optical measurement techniques to aircraft engine testing is described including measurement systems for turbine blade tip clearance compressor blade vibration fan blade profile turbine blade temperature and flow diagnostics. The signal and data processing associated with these techniques is emphasised and the prospects for further extending the use of optical methods on ground test and flight engines is discussed. The possibility of applying optical processing techniques is also briefly discussed.

The status of present optic technology in turbine engine control is highlighted, and future developments and trends are explored. Attention is given to a base engine control system configured with a primary and backup or standby control. Specific needs for integrated optic components in advanced turbine engine control systems are addressed. The optic harness and interconnect, as well as the electrooptic interface involving only coupling optic excitation and return signals are discussed. A number of 1:2 and 1:5 power splitters and combiners being fabricated using the ion-exchange technology on glass substrates are shown. The devices are potentially useful for the combination of various optical signals from a number of sensor units, and in addition calibration signals could be added prior to signal processing. Integrated optic and electrooptic interfaces are expected to evolve into the engine control environment. A concept for a multilayer electrooptic module which contains a single or multiple optic layers within the printed wiring card is illustrated.

The use of proton-exchange technology for the formation of integrated optical (IO) devices in X-cut lithium tantalate is briefly reviewed. By integrating a number of IO components such as phase modulators and directional couplers on lithium tantalate, a useful gyro chip can be realized. For the first time, performances of gyro chips (with and without fiber pigtails) fabricated in X-cut lithium tantalate using the proton-exchange method (PEM) will be reported.

The development of low loss, pigtailed Y-couplers in Lithium Niobate is described for operation at 830 nm wavelength. These couplers are fabricated using low loss S-bend transitions. Correlation is shown between S-bend parameters and Y-coupler losses.

We have fabricated Mach Zehnder type amplitude modulators with performance levels suitable for CATV industry. Fiber to fiber insertion loss with polarization preserving fibers of 45 dB has been achieved. We present detailed measurements of the sources of loss: mode mismatch loss in the Y junctions loss due to angled ends and Fresnel loss.

Silica waveguide integrated technologies have been developed based on a combination of the flame hydrolysis deposition and reactive ion etching which have the advantage of structure controllability and reproducibility. In addition we have developed the hybrid integration of passive components and packaging technology using Yttrium Aluminum Garnet (YAG) laser welding and simple adhesives. Silica optical integrated devices such as lxN splitters wavelength division multiplex/demultiplex (WDM) modules ring resonators Mach-Zehnder interferometers and optical switching devices can be commercially produced with these technologies.

Silica-on-silicon optical waveguides are seen as essential building blocks in the field of optical signal processing and future optical networks. This paper will review two technologies available to make these devices and present details of some of the devices and their applications.