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

Faithful Solid State Optical Memory with Dynamically Decoupled Spin Wave Storage

We report an optical memory in a rare earth doped crystal with long storage times, up to 20 ms, together with an optical bandwidth of 1.5 MHz. This is obtained by transferring optical coherences to nuclear spin coherences, which were then protected against environmental noise by dynamical decoupling. With this approach, we achieved a 33 fold increase in spin wave storage time over the intrinsic spin coherence lifetime. Comparison between different decoupling sequences indicates that sequences insensitive to initial spin coherence increase retrieval efficiency. Finally, an interference experiment shows that relative phases of input pulses are preserved through the whole storage process with a visibility close to 1, demonstrating the usefulness of dynamical decoupling for extending the storage time of quantum memories.Comment: 5 pages, 4 figure

Optical storage device

A new holographic image storage device which uses four-wave mixing in two photorefractive crystals is described. Photorefractive crystals promise information storage densities on the order of 10(exp 9) to 10(exp 12) bits per cubic centimeter at real-time rates. Several studies in recent years have investigated the use of photorefractive crystals for storing holographic image information. However, all of the previous studies have focused on techniques for storing information in a single crystal. The disadvantage of using a single crystal is that the read process is destructive. Researchers have developed techniques for fixing the information in a crystal so that it may be read many times. However, when fixed, the information cannot be readily erased and overwritten with new information. It two photorefractive crystals are used, holographic image information may be stored dynamically. That is, the stored image information may be read out more than once, and it may be easily erased and overwritten with new image information

ICI optical data storage tape

Optical data storage tape is now a commercial reality. The world's first successful development of a digital optical tape system is complete. This is based on the Creo 1003 optical tape recorder with ICI 1012 write-once optical tape media. Several other optical tape drive development programs are underway, including one using the IBM 3480 style cartridge at LaserTape Systems. In order to understand the significance and potential of this step change in recording technology, it is useful to review the historical progress of optical storage. This has been slow to encroach on magnetic storage, and has not made any serious dent on the world's mountains of paper and microfilm. Some of the reasons for this are the long time needed for applications developers, systems integrators, and end users to take advantage of the potential storage capacity; access time and data transfer rate have traditionally been too slow for high-performance applications; and optical disk media has been expensive compared with magnetic tape. ICI's strategy in response to these concerns was to concentrate its efforts on flexible optical media; in particular optical tape. The manufacturing achievements, media characteristics, and media lifetime of optical media are discussed

Transfer function characteristics of super resolving systems

Signal quality in an optical storage device greatly depends on the optical system transfer function used to write and read data patterns. The problem is similar to analysis of scanning optical microscopes. Hopkins and Braat have analyzed write-once-read-many (WORM) optical data storage devices. Herein, transfer function analysis of magnetooptic (MO) data storage devices is discussed with respect to improving transfer-function characteristics. Several authors have described improving the transfer function as super resolution. However, none have thoroughly analyzed the MO optical system and effects of the medium. Both the optical system transfer function and effects of the medium of this development are discussed

A quantum study of multi-bit phase coding for optical storage

We propose a scheme which encodes information in both the longitudinal and spatial transverse phases of a continuous-wave optical beam. A split detector-based interferometric scheme is then introduced to optimally detect both encoded phase signals. In contrast to present-day optical storage devices, our phase coding scheme has an information storage capacity which scales with the power of the read-out optical beam. We analyse the maximum number of encoding possibilities at the shot noise limit. In addition, we show that using squeezed light, the shot noise limit can be overcome and the number of encoding possibilities increased. We discuss a possible application of our phase coding scheme for increasing the capacities of optical storage devices.Comment: 8 pages, 7 figures (Please email author for a PDF file if the manuscript does not turn out properly

FirstLight: Pluggable Optical Interconnect Technologies for Polymeric Electro-Optical Printed Circuit Boards in Data Centers

The protocol data rate governing data storage devices will increase to over 12 Gb/s by 2013 thereby imposing unmanageable cost and performance burdens on future digital data storage systems. The resulting performance bottleneck can be substantially reduced by conveying high-speed data optically instead of electronically. A novel active pluggable 82.5 Gb/s aggregate bit rate optical connector technology, the design and fabrication of a compact electro-optical printed circuit board to meet exacting specifications, and a method for low cost, high precision, passive optical assembly are presented. A demonstration platform was constructed to assess the viability of embedded electro-optical midplane technology in such systems including the first ever demonstration of a pluggable active optical waveguide printed circuit board connector. High-speed optical data transfer at 10.3125 Gb/s was demonstrated through a complex polymer waveguide interconnect layer embedded into a 262 mm × 240 mm × 4.3 mm electro-optical midplane. Bit error rates of less than 10-12 and optical losses as low as 6 dB were demonstrated through nine multimode polymer wave guides with an aggregate data bandwidth of 92.8125 Gb/s