Abstract: A near-field optical system having one or more solid state lasers and an aerodynamically shaped slider which comprise a single integrated, monolithic device fabricated from the same base semiconductor material. The monolithic optical head can be quickly and easily attached to the read arm of an optical read/write device without requiring attachment of separate laser elements, and without micropositioning or use of optical microscopy for positioning the lasers. The optical head comprising a single semiconductor substrate including a first region which defines a slider having an air bearing surface, and at least one second, laser region which defines a diode laser, with the diode laser having an emission face which is substantially co-planar with the air bearing surface.

Abstract: An optical storage system and method having separate, independent format hologram writing and data writing mechanisms to allow optimization of data writing separately from format hologram recording. In its most general terms, the invention comprises an optical medium having a first, photoactive material responsive to a first, format hologram recording condition, and a second photo-active material, responsive to a second data writing condition, which is dispersed or dissolved in the first photoactive material. The second photoactive material may additionally be “erasable” under a third, erasing condition. The second photoactive material is preferably in the form of microparticles, microdroplets or microcapsules which are dispersed throughout the first photoactive material.

Abstract: The disclosed device is directed towards an optical data storage system. The optical data storage system comprises an optical medium including a servo plane and at least one data plane. A first laser is positioned to generate a servo laser beam and address the servo plane with a first servo focus spot. A second laser is positioned to generate a read-write laser beam and address the data plane with a second read-write focus spot. A first servo system is associated with the first laser and is configured to provide focus and tracking error correction according to servo information associated with the servo plane. A second servo system is associated with the second laser and is configured to provide focus and tracking error correction according to servo information associated with the data plane.

Abstract: A multi-frequency light source is disclosed. In one aspect, a multi-frequency light source may comprise a gain region defined by a first and second mirror. The gain region may have a resonant mode. The light source may also have an external cavity defined by a third mirror and the second mirror. The external cavity has plurality of resonant modes, including a plurality of contiguous desired modes of operation. The second mirror may be formed such that the multi-frequency light source operates at the desired modes of the external cavity.

Abstract: A multi-channel light source for use with a wavelength division multiplexed optical communication system includes a modified vertical cavity surface emitting laser (VCSEL) including a gain region and a resonator reflector layer at a first end for coupling with an optical fiber. An optical or electrical pumping source excites a gain region of the laser. An external cavity couples at a second end of the modified VCSEL and has a mirrored end for forming a resonant cavity with the resonator reflector layer permitting the light source to produce a multi-channel optical signal. The modified VCSEL has a cavity length that is substantially extended compared with a conventional VCSEL.

Abstract: Various aspects of multiple-channel light transmitting systems are disclosed. The system may include a multiple-wave length light source, a demultiplexer; a modulator, and a wavelocker. The wavelocker is configured to drive the light source such that said multiple wavelengths coincide with the ITU grid. The system may also include other elements including a locker or a mode-locking servo, where the servo is configured to adjust the mode locking method frequency to coincide with the spacing of the ITU grid. Further additional elements may include an optical amplifier or an equalizer. The equalizer may include a filter whose transmission function varies with wavelength.

Abstract: A multi-frequency light source is disclosed. In one disclosed aspect, the light source may comprise a gain region defined by a first and second mirror. The gain region may have corresponding resonant modes. An external cavity defined by a third mirror and said second mirror is also provided, with the external cavity having a plurality of resonant modes. The second mirror may be terminated with a layer of high reflectivity. In a further aspect, the second mirror may be terminated with an antiphase layer.

Abstract: A near-field laser and detector apparatus and method wherein both writing and reading of optical media can be carried out using the same laser operating in a single mode for both read and write operations. The single operational mode can be utilized with both edge emitting and surface emitting laser configurations, and allows readout via rear facet output power variation or by voltage variation across the laser. A small aperture laser is operated during read and write operations at a bias current which is higher than the threshold currents associated with feedback from high and low reflectivity regions of an optical medium. The bias current and laser structure provide a relatively high, continuous output power from the front emission facet of the laser to facilitate writing, while providing substantial fluctuation or change in output power from the rear emission facet to facilitate readout.

Abstract: An optical information storage system using optical storage media including multiple data layers or stacks wherein each of the multiple data stacks has a storage density comparable to a conventional single layer optical disk. The optical data storage system comprises an optical medium having a single dedicated servo layer and multiple data stacks which each contain an embedded servo format, a servo laser beam positioned to maintain a first focus point on the dedicated servo reference layer, a read-write laser beam positioned to maintain a second focus point on one of the data stacks, a first, dedicated servo system which provides focus and tracking error correction according to error signals generated from the dedicated servo layer, and a second, embedded servo system which provides focus and tracking error correction according to error signals generated from the data stacks.

Abstract: A tracking error signal generation apparatus and method which utilizes confocal detection with a split detector and a differencing circuit for generation of tracking error signals. A first lens is positioned in the path of a light beam returning from an optical medium. A pinhole is positioned in the path of the light beam after the first lens and proximate to the focal plane of the first lens. A second lens is positioned in the path of the light beam after the pinhole, and a split detector, having equal halves is positioned in the path of the light beam after the second lens. A differencing circuit is operatively coupled to each of the halves of the split detector. In operation, a light beam is focused by an optical head onto a track in the optical medium, and the reflection of the beam from the optical medium is directed through the first lens, through the pinhole, through the second lens, and onto the split detector.

Abstract: A method for storing data in a holographic storage medium comprises the steps of dividing a bit stream of binary data into data groups, encoding the data groups as binary patterns, and storing the binary patterns holographically as data pages. Each binary pattern comprises channel bits, wherein the number of “off” channel bits is greater than the number of “on” channel bits. To retrieve information from the storage medium, the medium is illuminated and resultant light signals are gathered. The light signals are converted to the binary patterns, and the binary patterns are converted to the data groups. Binary patterns stored in the storage medium only slightly perturb subsequent reading and writing of data, since the patterns have fewer “on” channel bits than “off” channel bits.

Abstract: An optical information medium comprising at least two data layers for bearing recorded information, and a servo layer for bearing tracking servo, information which is independently formed from the data layers; wherein the medium is used with a recording or reading system wherein a data beam for recording or reading the data in the data layer and a servo beam for reading the tracking servo information in the servo layer are used, and the servo layer is read by the servo beam that had passed through the data layer; and a filter layer is disposed between the data layer and the servo layer, and the filter layer exhibits higher absorption to the data beam than to the servo beam.

Abstract: A light source is disclosed. In one aspect, a gain region defined by a first and second mirror is provided having a corresponding resonant mode, and an external cavity defined by a third mirror and the second mirror is also provided having a plurality of resonant modes. A birefringent crystal is then disposed within said external cavity for the purpose of controlling the state of polarization.

Abstract: An optical data storage system and method comprising a photopolymer medium having generally a polymerizable monomer, an active binder, a first, hologram recording polymerization initiator, and a second, data writing polymerization initiator. The monomer is preferably a cationic ring-opening monomer. The hologram recording polymerization initiator preferably comprises a sensitizer and photoacid generator which initiate a first polymerization in the medium which defines a format hologram. The format hologram recording is carried out via interference of a signal and reference beam, with the sensitizer being specific for the wavelength(s) of the signal and reference beams. The hologram recording polymerization is only partial and does not consume all of the monomer present in the photopolymer medium.

Abstract: A light source is disclosed for use optical communications systems. In one aspect, a gain region defined by a first and second mirror is provided having a corresponding resonant mode, and an external cavity defined by a third mirror and the second mirror is also provided having a plurality of resonant modes. The second mirror is configured such that one of the external cavity resonant modes is selected. The single channel laser has wavelength precision sufficient to eliminate the need for an external wavelocker, and has an external cavity capable of being directly modulated in a chirp-free manner.

Abstract: A digital electronic camera includes a holographic medium, an imaging array disposed at a focal plane for converting optical information to digital information; and an optical system configured to store the digital information onto the holographic medium. An optical system for retrieving images stored in the medium may be provided inside the camera or as a separate appliance.

Abstract: A reference beam telescope, which is also referred to as a relay imaging system for a reference beam, using reflection optics is disclosed. The relay imaging system according to the present invention comprises at least one concave mirror and one convex mirror. A reference beam is reflected at least twice by the concave mirror and once by the convex mirror. The output reference beam is collimated if the input reference beam is collimated. This relay imaging system is used in a holographic storage system to deliver the reference beam to the holographic storage medium. In particular, this system can be used for angular multiplexing in a holographic storage system.

Abstract: A photoactive medium has a complex format grating written thereon, the complex format grating including at least three component gratings, each of the component gratings characterized by a unique grating vector. Methods for writing the complex format grating include the steps of providing a photoactive medium; and focussing a plurality of pairs of mutually coherent light beams into a focal plane in the medium.

Abstract: The present invention comprises an optical data storage system utilizing a host material and molecules that exhibit non-linear absorption dissolved therein. The non-linear absorbing molecules allow for energy in the form of heat to be generated during the optical data storage process. This heat provides for localized alterations to occur in the pre-formatted holographic grating. The non-linear feature of these molecules allow for alterations to occur at specific depths and locations within the storage medium while limiting the secondary effects on other locations within the storage medium. The molecules exhibiting non-linear absorption may be selected from the group of molecules exhibiting two-photon absorption or reverse saturable absorption. The invention also comprises a method for preparing the optical storage medium, an optical data storage device comprising the optical data storage medium and having a format hologram stored within the medium.

Abstract: An apparatus and method for optical data storage and/or retrieval using an optical data storage medium having a spatially-modulated refractive index that can be altered locally with optical methods. Data can be written at a plurality of depths throughout the volume of the medium using a write beam and relatively simple and inexpensive optical components. The write beam stores data locally by physical distortion of the medium at discrete storage locations. The alterations can be detected as variations in the reflectivity of the storage locations using a retrieval beam.