Regimes of regular pulse generation at remote optical wavelengths in asymmetric quantum-well heterostructure lasers have been examined in detail. Influence of the heterostructure parameters and pump current density on frequency, duration, and magnitude of light spikes and on phase shift between pulses of radiation at different wavelengths has been studied. Design of optimal band energy structures for novel type of laser sources is proposed.

We successfully placed a metal strip along the core of an optical fiber, see Fig. 1. These devices can be used as polarizers. Light polarized parallel to the metal strip is absorbed while light polarized perpendicular to the metal strip is absorbed less. Potentially large ratios of transmitted to absorbed light can be achieved in relatively short pieces of fiber. The Metal Strip Polarizing Fibers (MSPFs) are typically about 5 mm long. We report both on the fabrication process and some preliminary test.

The demonstration of real-space electron transfer in (Ga,In)As/(Al,In)As asymmetric double quantum wells is reported. Real-space electron transfer is then shown to be an efficient mechanism to enhance the electroabsorptive properties of optical fiber compatible opto-electronic semiconductor heterostructures.

Application of the photorefractive effect as a time integrating element in optical signal processing is discussed.

Photonic excitations of the electronic and nuclear spin system in a variety of photonic materials are proposed to serve as the foundation of a potential realization of a Photonic Quantum (mechanical) Computer (PQC). Quantum bits (q-bits) for this new class of computational architecture physically manifest themselves as spin states in the media. Spin interaction Hamiltonians are discussed corresponding to various spin interaction topologies. Quantum logics, algebras, and algorithms are discussed as potential PQC applications.

We present an experimental study of mode-locking in linear- cavity erbium-doped fiber lasers which use MQW mirrors as saturable reflectors. From the results of single-beam, nonlinear transmission measurements, we have found the saturation intensity of the MQW mirrors to be greatly dependent on the wavelength of the incident radiation with respect to the MQW bandedge. For satisfactory mode-locked laser performance, we have found that the MQW mirrors must have a sufficiently high saturation intensity to provide the required intensity discrimination to initiate and sustain modelocked operation.

We describe a simple efficient erbium fiber laser mode locked with a multiple quantum well saturable absorber whose reflectivity can be controlled with an applied electric field. The laser produces 30 ps, duration pulses at a repetition rate of 3.25 MHz.

We present the results of an experimental investigation of field-dependent space-charge build-up in (Ga,In)As/(Al,In)As asymmetric double quantum well structures. By using low- temperature photoluminescence spectroscopy, we have found that charge separation dramatically increases the magnitude of the applied field required to achieve resonance (and beyond) of the lowest allowed electron levels in the narrow and wide wells.

We have fabricated and tested coupled integrated coupled and branching waveguide lasers in Nd glass substrates1 . By making two or more parallel diffused channel or ridge waveguides close together on rare-earth doped glass substrates as shown in Fig's 1 , a set of coupled waveguide lasers can be fabricated which produce two closely spaced light waves, the symmetric and anti symmetric modes of the structure. The difference between their frequencies is in the microwave regime. Such devices can serve as single-sideband optical carrier sources. We have fabricated both diffused channel waveguides as shown in Fig. 1 a and ridge waveguides as shown in Fig. lb. The ridge waveguides can be bend through smaller radii than diffused wave guides for the same loss of light.

Subcarrier links and subcarrier multiplexed optical networks find a wide range of applications such as video delivery, antenna remoting, and local area networks. This paper presents the foundations for the realization of all-optical subcarrier links and subcarrier multiplexed optical networks based on the optical current-controlled oscillators (CCO). Using one embodiment of the optical CCO employing a two- section laser diode, we first present the static and modulation characteristics of the periodic-orbit subcarrier of the optical CCO. Then, the performances of an FM subcarrier optical link are estimated using realistic device parameters.

A cascaded optical logic system is reported in which an array of vertical-cavity surface-emitting lasers (VCSELs) selectively controls an array of symmetric self-electro- optic effect devices (S-SEEDs). This configuration allows interconnect masks to be reconfigured dynamically by selectively disabling microlasers through a host controller. A single-array system in which an optical input is sequenced through successive rows of an S-SEED array is demonstrated. The system is operated by setting the initial states of the S-SEEDs using the VCSELs and then optically scrolling the data from row to row.

Quadratic lead lanthanum zirconate titanate (PLZT) is a material demonstrating a strong quadratic electro-optic effect. Both sides of the PLZT wafer were used so that the electro-optic interaction length was equal to the thickness of the PLZT substrate. On-substrate resistive networks were fabricated by evaporating chromium, a less conductive metal, in order to produce the required voltage distribution among the electrodes. The device is polarization insensitive because it takes advantage of the longitudinal electric field. The device yielded a measured steering angle of .04 degree(s). This paper describes the design, fabrication, and experimental results of a PLZT based electro-optic beam steering device.

Lateral carrier transport has been used to enhance the recovery time of bandgap resonant nonlinear transmission changes in multiple quantum well waveguide structures. Recovery times on the order of 90 ps have been measured in our samples. Such technique is applicable to all-optical and optoelectronic integrated optic switches.

In this paper, we present the intracavity gain dynamics of hybrid modelocked external cavity semiconductor lasers. Using the pump-probe method, the optical gain and transmittance of a modelocked external cavity laser diode and saturable absorber were measured, respectively. The pulse shaping processes were measured by investigating the chirp of the optical pulse at the output coupler, before and after the saturable absorber. These measurements were obtained by a spectrally resolved cross correlation technique. In comparison with the previous studies of the single pass dynamics in semiconductor optical amplifiers, the dynamics of the nonlinearities affecting the pulse shaping within the laser cavity is less dramatic owing to the longer intracavity pulse widths. It was also observed that the linear GVD plays an important role in the shaping of the pulse envelop and linearizing the pulse chirp.

Using an uncoated monolithic single-contact distributed feedback (DFB) laser, transmission of 2 Mb/s data at a subcarrier frequency of 35 GHz over 2.2 km of optical fiber by resonant modulation is demonstrated. Modulation response of 60 MHz with more than 1 GHz of enhancement at round trip frequency, carrier-to-noise ratio and bit-error-rate results are reported. The tolerance of the resonant round-trip frequency to the DFB facet cleaving process and the device length uncertainty due to cleaving is also addressed in detail by computer simulation.

A all-optical switching devices based on ultrafast bound- electronic nonlinearity have the potential to perform signal processing and routing at a speed in excess of 1 Thz. So far, AlGaAs operating at wavelength below half the band gap has been found to be one of the best materials for demonstrating and testing such devices and device concepts. A bright spatial soliton is a non-diffracting self-guided beam which exists due to an interplay between the self- focusing nonlinearity and the linear diffraction. In this talk, we will experimentally demonstrate all-optical switching based on spatial soliton dragging.

Semiconductor laser diodes play an important role in synchronous optical networks as sources of optical modelocked pulse trains with robust timing stability. In this paper, it is demonstrated how these diodes may be used in such applications as optical clock distribution, photonic network synchronization, and all-optic clock recovery. Emphasis is placed on all-optical clock recovery with preliminary results presented.

In this paper, we have analyzed the performance of coherent optical systems using cascaded optical amplifiers. The relative performance of binary asynchronous, binary synchronous and M-ary FSK systems are compared in terms of power penalties due to amplifier input power and noise accumulation at various bit rates of operation. This completes the previous investigations that were limited to the analysis of photonic amplifier based coherent optical asynchronous systems.

Conventional true time delay beamforming and steering devices rely on switching between various lengths of delay line. Therefore only discrete delays are possible. Proposed is a new photonics concept for true time delay beamforming which provides a finely controlled continuum of delays with switching speeds on the order of 10's of nanoseconds or faster. The architecture uses an array of waveguide cavities with different resonate frequencies to channelize the signal. Each spectral component of the signal is phase shifted by an amount proportional to the frequency of that component and the desired time delay. These phase shifted spectral components are then summed to obtain the delayed signal. This paper provides an overview of the results of a Phase I SBIR contract where this concept has been refined and analyzed. The parameters for an operational system are determined and indication of the feasibility of this approach is given. Among the issues addressed are the requirements of the resonators and the methods necessary to implement fiber optic Bragg gratings as these resonators.

We used the discrete wavelet transform to approximate an image at a lower resolution in preparation for object recognition using correlation techniques. We cross- correlated the low-resolution image with a similarly processed image containing an object of interest. Then, we synthesized the cross-correlation result to the resolution of original image. Using this approach, we avoided cross- correlating an image multiple times and passing information between levels of an image representation such as an image pyramid. We satisfactorily identified objects at 1/4 resolution using the wavelet representation and binary phase-only filters. We chose wavelets based on their impulse response and found that different wavelet filters gave significantly different autocorrelation peak, and SNR values.

This paper will detail the basic characteristics and performance of a diffractive optic imaging spectrometer (DOIS). Diffractive optical element technology combined with a conventional CCD camera produces an elegant configuration for adding spectroscopy capabilities to current imaging systems. Its resolution rivals that of competing technologies, capable of hyperspectral resolution when used along with basic image processing techniques. DOIS is a rugged, economical, programmable, practical image spectrometer that can be adapted for use in visible, infra- red, and ultraviolet spectra for a multitude of applications.

The number of photonic devices based on integrated-optic waveguides with domain-inverted regions are currently experiencing rapid expansion. Implementation of domain reversals in guided-wave structures brings about an opportunity to significantly increase device efficiency as well as to simplify the structure. Domain inversion has proven beneficial both for nonlinear devices and electro- optic modulators. It should be noted in this regard that while the use of domain reversals for nonlinear interactions has been studied extensively, little information on the characteristics of electro-optic devices with such domain- inverted regions is available in the literature. This paper addresses the latter issue by studying the performance of an integrated-optic Mach-Zehnder interferometer modulator with electric-field poled domain-inverted sections. With this device, both the realization of waveguide sections with opposing values of the electro-optic coefficient (r₃₃), and the measurement of the value of r₃₃ have been demonstrated experimentally.

We describe a nonlinear joint transform correlator-based two-layer neural network that uses a supervised learning algorithm for real-time face recognition. The system is trained with a sequence of facial images and is able to classify an input face image in real-time. Computer simulations and optical experimental results are presented. The processor can be manufactured into a compact low-cost optoelectronic system. The use of the nonlinear joint transform correlator provides good noise robustness and good image discrimination.

Diagnoses of cancers and pulmonary embolism are performed by visually interpreting medical data on computer graphics displays. Interpretation aids for medical diagnosis and treatment are not available. The optical information processor system presented in this paper can be used as a second opinion in detecting cancers and classifying images; the final diagnosis is made by a physician. The optical information processing system uses a novel spatial multiplexing technique that allows several images to be processed simultaneously using the same spatial light modulator. Simulation results for liquid crystal display operated in a novel amplitude coupled with binary phase mode is described. In addition, simulation results for a phase modulating micro-mirror spatial light modulator are presented. Results using clinical data show that the optical information processing system can yield a diagnosis rate of 86%.

It has been a goal to develop fiber optic link components that offer high performance and environmental robustness. This paper describes the performance of a lithium niobate modulator, laser sources, and detectors when evaluated against the requirements encountered on airborne platforms. It was shown that the complete fiber optic link provided for high dynamic range operation to 18 GHz under the environmental stresses of the application.

Research was performed to determine the performance characteristics of emitter-coupled logic compatible phase modulators (1.3 micrometers and 1.5 micrometers ), bias control modulators (1.3 micrometers ), and diode pumped Nd:YAG lasers in various environments. The stability of the materials and the performance of the devices when exposed to elevated temperatures, vibration and humidity were examined to determine and assess potential failure mechanisms. Results of the research has led to improvements in the modulator packages and laser mounting structures.

In this paper we present results from measurements on a recently developed CMOS integrated circuit containing three Active Pixel Image Sensors (APS) with 32 X 32 pixels. The chip has been developed using a standard CMOS DLP/DLM 1.2 micrometers process line from Austria Micro Systems. Two of the APS image sensors use photogate pixels and the third uses photodiodes. A series of measurements, including quantum efficiency, conversion gain, read noise, fixed pattern noise, linearity, uniformity and dark current rates, have been carried out in order to compare the detector performance between CMOS-APS photodiode and photogate pixels. The obtained results confirm that APS detector performance is comparable to Charge-coupled devices.