Programmable image associative memory using an optical disk and a photorefractive crystal

The optical disk is a computer-addressable binary storage medium with very high capacity. More than 10^10 bits of information can be recorded on a 12-cm-diameter optical disk. The natural two-dimensional format of the data recorded on an optical disk makes this medium particularly attractive for the storage of images and holograms, while parallel access provides a convenient mechanism through which such data may be retrieved. In this paper we discuss a closed-loop optical associative memory based on the optical disk. This system incorporates image correlation, using photorefractive media to compute the best association in a shift-invariant fashion. When presented with a partial or noisy version of one of the images stored on the optical disk, the optical system evolves to a stable state in which those stored images that best match the input are temporally locked in the loop

Optical implementations of radial basis classifiers

We describe two optical systems based on the radial basis function approach to pattern classification. An optical-disk-based system for handwritten character recognition is demonstrated. The optical system computes the Euclidean distance between an unknown input and 650 stored patterns at a demonstrated rate of 26,000 pattern comparisons/s. The ultimate performance of this system is limited by optical-disk resolution to 10^11 binary operations/s. An adaptive system is also presented that facilitates on-line learning and provides additional robustness

Image correlators using optical memory disks

Image correlators are described and experimentally demonstrated that are implemented using optical memory disks to store a large library of reference images

Optical memory: introduction by the feature editors

The contributions to this feature issue represent a wide range of topics in optical memory

Optical memory disks in optical information processing

We describe the use of optical memory disks as elements in optical information processing architectures. The optical disk is an optical memory devicew ith a storage capacity approaching 1010b its which is naturally suited to parallel access. We discuss optical disk characteristics which are important in optical computing systems such as contrast, diffraction efficiency, and phase uniformity. We describe techniques for holographic storage on optical disks and present reconstructions of several types of computer-generated holograms. Various optical information processing architectures are described for applications such as database retrieval, neural network implementation, and image correlation. Selected systems are experimentally demonstrated

Task-specific information for imaging system analysis

ABSTRACT We present a novel method for computing the information content of an image. We introduce the notion of task-specific information (TSI) in order to quantify imaging system performance for a given task. This new approach employs a recently-discovered relationship between the Shannon mutual-information and minimum estimation error. We demonstrate the utility of the TSI formulation by applying it to several familiar imaging systems including (a) geometric imagers, (b) diffraction-limiter imagers, and (c) projective/compressive imagers. Imaging system TSI performance is analyzed for two tasks: (a) detection, and (b) classification

A single shot coherent Ising machine based on a network of injection-locked multicore fiber lasers

Combinatorial optimization problems over large and complex systems have many applications in social networks, image processing, artificial intelligence, computational biology and a variety of other areas. Finding the optimized solution for such problems in general are usually in non-deterministic polynomial time (NP)-hard complexity class. Some NP-hard problems can be easily mapped to minimizing an lsing energy function. Here, we present an analog all-optical implementation of a coherent lsing machine (CIM) based on a network of injection-locked multicore fiber (MCF) lasers. The Zeeman terms and the mutual couplings appearing in the Ising Hamiltonians are implemented using spatial light modulators (SLMs). As a proof-of-principle, we demonstrate the use of optics to solve several Ising Hamiltonians for up to thirteen nodes. Overall, the average accuracy of the CIM to find the ground state energy was similar to 90% for 120 trials. The fundamental bottlenecks for the scalability and programmability of the presented CIM are discussed as well.Office of Naval Research (ONR) MURI program on Optical Computing [N00014-14-1-0505]; NSF ERC CIAN [EEC-0812072]; State of Arizona TRIFOpen access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

High-fidelity, broadband stimulated-Brillouin-scattering-based slow light using fast noise modulation

We demonstrate a 5-GHz-broadband tunable slow-light device based on stimulated Brillouin scattering in a standard highly-nonlinear optical fiber pumped by a noise-current-modulated laser beam. The noise modulation waveform uses an optimized pseudo-random distribution of the laser drive voltage to obtain an optimal flat-topped gain profile, which minimizes the pulse distortion and maximizes pulse delay for a given pump power. Eye-diagram and signal-to-noise ratio (SNR) analysis show that this new broadband slow-light technique significantly increases the fidelity of a delayed data sequence, while maintaining the delay performance. A fractional delay of 0.81 with a SNR of 5.2 is achieved at the pump power of 350 mW using a 2-km-long highly nonlinear fiber with the fast noise-modulation method, demonstrating a 50% increase in eye-opening and a 36% increase in SNR compared to a previous slow-modulation method

Experimental characterization of a 400 Gbit/s orbital angular momentum multiplexed free-space optical link over 120 m

We experimentally demonstrate and characterize the performance of a 400-Gbit/s orbital angular momentum (OAM) multiplexed free-space optical link over 120- meters on the roof of a building. Four OAM beams, each carrying a 100-Gbit/s QPSK channel are multiplexed and transmitted. We investigate the influence of channel impairments on the received power, inter-modal crosstalk among channels, and system power penalties. Without laser tracking and compensation systems, the measured received power and crosstalk among OAM channels fluctuate by 4.5 dB and 5 dB, respectively, over 180 seconds. For a beam displacement of 2 mm that corresponds to a pointing error less than 16.7 μrad, the link bit-error-rates are below the forward error correction threshold of 3.8×10-3 for all channels. Both experimental and simulation results show that power penalties increase rapidly when the displacement increases