Abstract: A receiver applies a calibration method to compensate for skew between input channels. The receiver skew is estimated by observing the coefficients of an adaptive equalizer which adjusts the coefficients based on time-varying properties of the multi-channel input signal. The receiver skew is compensated by programming the phase of the sampling clocks for the different channels. Furthermore, during real-time operation of the receiver, channel diagnostics is performed to automatically estimate differential group delay and/or other channel characteristics based on the equalizer coefficients using a frequency averaging or polarization averaging approach. Framer information can furthermore be utilized to estimate differential group delay that is an integer multiple of the symbol rate. Additionally, a DSP reset may be performed when substantial signal degradation is detected based on the channel diagnostics information.

Abstract: A receiver applies a calibration method to compensate for skew between input channels. The receiver skew is estimated by observing the coefficients of an adaptive equalizer which adjusts the coefficients based on time-varying properties of the multi-channel input signal. The receiver skew is compensated by programming the phase of the sampling clocks for the different channels. Furthermore, during real-time operation of the receiver, channel diagnostics is performed to automatically estimate differential group delay and/or other channel characteristics based on the equalizer coefficients using a frequency averaging or polarization averaging approach. Framer information can furthermore be utilized to estimate differential group delay that is an integer multiple of the symbol rate. Additionally, a DSP reset may be performed when substantial signal degradation is detected based on the channel diagnostics information.

Abstract: A receiver applies a calibration method to compensate for skew between input channels. The receiver skew is estimated by observing the coefficients of an adaptive equalizer which adjusts the coefficients based on time-varying properties of the multi-channel input signal. The receiver skew is compensated by programming the phase of the sampling clocks for the different channels. Furthermore, during real-time operation of the receiver, channel diagnostics is performed to automatically estimate differential group delay and/or other channel characteristics based on the equalizer coefficients using a frequency averaging or polarization averaging approach. Framer information can furthermore be utilized to estimate differential group delay that is an integer multiple of the symbol rate. Additionally, a DSP reset may be performed when substantial signal degradation is detected based on the channel diagnostics information.

Abstract: A receiver applies a calibration method to compensate for skew between input channels. The receiver skew is estimated by observing the coefficients of an adaptive equalizer which adjusts the coefficients based on time-varying properties of the multi-channel input signal. The receiver skew is compensated by programming the phase of the sampling clocks for the different channels. Furthermore, during real-time operation of the receiver, channel diagnostics is performed to automatically estimate differential group delay and/or other channel characteristics based on the equalizer coefficients using a frequency averaging or polarization averaging approach. Framer information can furthermore be utilized to estimate differential group delay that is an integer multiple of the symbol rate. Additionally, a DSP reset may be performed when substantial signal degradation is detected based on the channel diagnostics information.

Abstract: A receiver applies a calibration method to compensate for skew between input channels. The receiver skew is estimated by observing the coefficients of an adaptive equalizer which adjusts the coefficients based on time-varying properties of the multi-channel input signal. The receiver skew is compensated by programming the phase of the sampling clocks for the different channels. Furthermore, during real-time operation of the receiver, channel diagnostics is performed to automatically estimate differential group delay and/or other channel characteristics based on the equalizer coefficients using a frequency averaging or polarization averaging approach. Framer information can furthermore be utilized to estimate differential group delay that is an integer multiple of the symbol rate. Additionally, a DSP reset may be performed when substantial signal degradation is detected based on the channel diagnostics information.

Abstract: A receiver applies a calibration method to compensate for skew between input channels. The receiver skew is estimated by observing the coefficients of an adaptive equalizer which adjusts the coefficients based on time-varying properties of the multi-channel input signal. The receiver skew is compensated by programming the phase of the sampling clocks for the different channels. Furthermore, during real-time operation of the receiver, channel diagnostics is performed to automatically estimate differential group delay and/or other channel characteristics based on the equalizer coefficients using a frequency averaging or polarization averaging approach. Framer information can furthermore be utilized to estimate differential group delay that is an integer multiple of the symbol rate. Additionally, a DSP reset may be performed when substantial signal degradation is detected based on the channel diagnostics information.

Abstract: A receiver applies a calibration method to compensate for skew between input channels. The receiver skew is estimated by observing the coefficients of an adaptive equalizer which adjusts the coefficients based on time-varying properties of the multi-channel input signal. The receiver skew is compensated by programming the phase of the sampling clocks for the different channels. Furthermore, during real-time operation of the receiver, channel diagnostics is performed to automatically estimate differential group delay and/or other channel characteristics based on the equalizer coefficients using a frequency averaging or polarization averaging approach. Framer information can furthermore be utilized to estimate differential group delay that is an integer multiple of the symbol rate. Additionally, a DSP reset may be performed when substantial signal degradation is detected based on the channel diagnostics information.

Abstract: A receiver applies a calibration method to compensate for skew between input channels. The receiver skew is estimated by observing the coefficients of an adaptive equalizer which adjusts the coefficients based on time-varying properties of the multi-channel input signal. The receiver skew is compensated by programming the phase of the sampling clocks for the different channels. Furthermore, during real-time operation of the receiver, channel diagnostics is performed to automatically estimate differential group delay and/or other channel characteristics based on the equalizer coefficients using a frequency averaging or polarization averaging approach. Framer information can furthermore be utilized to estimate differential group delay that is an integer multiple of the symbol rate. Additionally, a DSP reset may be performed when substantial signal degradation is detected based on the channel diagnostics information.

Abstract: A receiver applies a calibration method to compensate for skew between input channels. The receiver skew is estimated by observing the coefficients of an adaptive equalizer which adjusts the coefficients based on time-varying properties of the multi-channel input signal. The receiver skew is compensated by programming the phase of the sampling clocks for the different channels. Furthermore, during real-time operation of the receiver, channel diagnostics is performed to automatically estimate differential group delay and/or other channel characteristics based on the equalizer coefficients using a frequency averaging or polarization averaging approach. Framer information can furthermore be utilized to estimate differential group delay that is an integer multiple of the symbol rate. Additionally, a DSP reset may be performed when substantial signal degradation is detected based on the channel diagnostics information.

Abstract: A single monolithic semiconductor substrate comprises a first side and a second side. The first side includes an air bearing surface. A laser integrates with the first side. The laser has an emission facet substantially co-planer with the air bearing surface. A contact pad on the second side electronically bridges to the laser.

Abstract: A transmitter subsystem generates an optical signal which contains multiple subbands of information. The subbands have different polarization. For example, in one approach, two or more optical transmitters generate optical signals which have different polarization. An optical combiner optically combines the optical signals into a composite optical signal for transmission across an optical fiber. In another aspect, each optical transmitter generates an optical signal containing both a lower optical sideband and an upper optical sideband (i.e., a double sideband optical signal). An optical filter selects the upper optical sideband of one optical signal and the lower optical sideband of another optical signal to produce a composite optical signal.

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. A slider region of the semiconductor substrate includes an air bearing surface, adjacent the p-clad layer, which is aerodynamically structured and configured to define a slider.

Abstract: A system and method are disclosed for recording information on a phase change medium is disclosed. The method includes irradiating a region of the phase change medium with a first dose of laser energy. A first portion of the region is irradiated with a second dose of laser energy in a manner that causes the first portion of the region irradiated with the second dose of laser energy to be in a different state than a second portion of the region that is not irradiated by the second dose of laser energy.

Abstract: A transmitter subsystem generates an optical signal which contains multiple subbands of information. The subbands have different polarizations. For example, in one approach, two or more optical transmitters generate optical signals which have different polarizations. An optical combiner optically combines the optical signals into a composite optical signal for transmission across an optical fiber. In another approach, a single optical transmitter generates an optical signal with multiple subbands. The polarization of the subbands is varied, for example by using a birefringent crystal. In another aspect of the invention, each optical transmitter generates an optical signal containing both a lower optical sideband and an upper optical sideband (i.e., a double sideband optical signal). An optical filter selects the upper optical sideband of one optical signal and the lower optical sideband of another optical signal to produce a composite optical signal.

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 holographic storage and retrieval system for use in co-propagating or counter-propagating geometries having a common optical relay for guiding a signal beam and a reference beam along a common optical axis to a holographic medium to write a hologram therein. The optical relay has an object region imaging quality such that at least 65% and preferably at least 80% of the nominal luminous energy from object pixels is encompassed or "ensquared" by the corresponding image pixels. Additionally, the optical relay has a high total numerical aperture (N.A.) of about 0.83, a pixel N.A. of approximately 0.04 for the signal beam. The system of the invention can be used with holographic storage media in the form of disks, tapes or bulk holographic crystals.

Abstract: A method for coded-wavelength multiplexing according to which a signal waves S.sub.i (r) is recorded in a holographic medium in a counter-propagating geometry using corresponding writing reference waves R.sub.i (r). The method involves selecting discrete wavelengths .lambda. and encoding reference wave vectors .rho..sub.l which make up writing reference waves R.sub.i (r) such that the writing reference waves R.sub.i (r) at each wavelength .lambda. are orthogonal. The stored signal waves S.sub.i (r) are reconstructed in the form of reconstruction waves A.sub.c (.sigma.) with reconstruction reference waves R.sub.c (r) selected from among the writing reference waves R.sub.i (r). In the event of angular multiplexing of the reference wave vectors .rho..sub.l, it is possible to use one reference wave to produce a number of reconstruction waves A.sub.c (.sigma.) and generate a mosaic of desired holographic pages.

Abstract: An encryption method and apparatus for holographic data storage are disclosed. In a system using orthogonal phase-code multiplexing, data is encrypted by modulating the reference beam using an encryption key K represented by a unitary operator. In practice, the encryption key K corresponds to a diffuser or other phase-modulating element placed in the reference beam path, or to shuffling the correspondence between the codes of an orthogonal phase function and the corresponding pixels of a phase spatial light modulator. Because of the lack of Bragg selectivity in the vertical direction, the phase functions used for phase-code multiplexing are preferably one dimensional. Such phase functions can be one-dimensional Walsh functions. The encryption method preserves the orthogonality of reference beams, and thus does not lead to a degradation in crosstalk performance.

Abstract: A video image F?k! is identified as a basis image and stored as a basis page S?k! in a holographic storage medium. A subsequent image F?k+n! is stored by recording in the medium a page S?k+n!=F?k+n!-a?k!F?k!, where a?k!.noteq.0 and preferably a?k!=1. The page S?k! is recorded with a reference beam R?k!, while S?k+n! is recorded with a reference beam R?k+n! orthogonal to R?k!. The basis page is reset whenever the average intensity of a page to be stored exceeds a predetermined threshold. An image F'?k! is retrieved by reading basis page S?k! and letting F'?k!=S?k!. Subsequent images F'?k+n! are retrieved as S?k+n!+b?k!S?k!, where b?k!.noteq.0 and preferably b?k!=a?k!=1. The page addition step is performed coherently, i.e. by accessing the medium with a reference wave function R?k+n!+b?k!R?k!.

Abstract: A method of choosing an angle between a reference beam and a signal beam in a holographic storage apparatus is presented. The angle between the reference and signal beams can be optimized in light of crosstalk, scattering and wavelength seperation considerations.