Essex Corporation

Northrop Grumman Systems Corporation

The United States of America As Represented by the Director of the

Terry M Turpin

James L Lafuse

Leslie H Gesell

Keith R Frampton

Fred F Froehlich

Fred F Froelich

Bruce D Nichols

Craig H Price

D Bruce Nichols

An optical code division multiple access communication system using a processor processes at least one collimated input beam which has been modulated with a data signal to produce multiple time-delayed output beams. The multiple time-delayed output beams are spatially distributed and independently phase shifted. An integration lens receives the phase modulated output beams and reintegrates the phase modulated output beams into a single encoded beam with a time series chip sequence. The integrated encoded beam is transmitted. A receiving system includes a processor to process the encoded collimated light beams received from a transmitter to produce multiple time-delayed output beams. The multiple time-delayed output beams are spatially distributed and independently phase shifted. An integration lens receives the phase-shifted output beams and reintegrates the phase-shifted output beams into a single decoded beam.

Optical CDMA communications system using OTDL device

A method and apparatus for secure transmission of an information-containing optical signal. An optical signal is divided into a first plurality of sub-bands. Each of the sub-bands is modified to encrypt the information contained in the optical signal. The modified sub-bands are combined into a combined optical signal. The combined optical signal is divided into a second plurality of sub-bands. Each of the second plurality of sub-bands is modified to decrypt the previously encrypted information contained in the optical signal.

Private and secure optical communication system using an optical tapped delay line

An Optical Tapped Delay Line (OTDL), which resolves multiple wavelength signals having extremely narrow wavelength spacing, is combined with other known optical devices to provide a wide variety of optical signal processing applications, including: multiplexing and de-multiplexing a multi-channel signal; adding a signal to, or dropping a signal from, a multi-channel optical signal; specialized coding processing such as generating code division multiple access signals; wavelength locking (stabilizing) a signal; filtering a signal; and analyzing and monitoring a signal spectrum. The OTDL spatially separates individual channels to allow separate processing on each channel. Fixed and tunable embodiments are identified in appropriate cases. Bulk, hybrid, and integrated optical embodiment and methods of fabrication are described, as are curved self-focusing and evanescent embodiments of OTDL devices. The devices and processes disclosed have particular application to dense wavelength division multiplexing (DWDM) and permit a significant improvement in the quantity of information that can be carried on DWDM signals while enhancing signal quality.

Method and apparatus for optical signal processing using an optical tapped delay line

A method and apparatus for enhancing the receiving and information identification functions of multiple access communications systems by employing one or more optical processors configured as a bank of 1-D correlators. The present invention is particularly useful in a DS/SS CDMA communications system, resulting in a multiuser CDMA system that approaches carrier to noise performance (C/N) as opposed to being limited by multiple access interference (MAI). The correlators are arranged in parallel to detect and/or demodulate the received signal, in conjunction with one or more complex algorithms to perform near-optimum multiuser detection, perform multipath combining and/or perform carrier Doppler compensation. An improved receiver in accordance with the present invention comprises means for receiving a plurality of signals transmitted through a communications channel; signal conversion means for converting the received signals into a form suitable for input to the multichannel correlator; a multichannel optical correlator for identifying the presence of particular waveforms and estimating the relative time delay or delays, carrier frequency offset from expected, RF amplitude and RF phase for each received spread spectrum waveform present in the received plurality of signals; a controller for determining and providing to the optical correlator the appropriate set of reference hypotheses; and one or more receiver algorithms depending on the exact receiver function to be performed.

Optical processor enhanced receiver architecture (opera)

An Optical Tapped Delay Line (OTDL) is combined with other known optical apparatuses to provide an add-drop multiplexer for a wavelength division multiplexing fiber optic network. Each output beam of the OTDL is spatially distinguishable in free space. This wavelength accessibility enables selection of one or more of the optical beams for adding or dropping. The system can be a fixed or tunable single channel add/drop system, a fixed or tunable multi-channel add/drop system, or a fully programmable add/drop system.

Wavelength division multiplexing add-drop multiplexer using an optical tapped delay line

An OTDL device in accordance with the present invention is a method for and device for spatially resolving the wavelengths in an optical signal, i.e., channelizing or demultiplexing. The device is based on a tapped optical delay line.

Optical tapped delay line

A method and apparatus for producing an image of a target area, by: at an observation location spaced from the target area, transmitting a beam of electromagnetic radiation toward the target area, and receiving reflections of the radiation from the target area; providing a representation of the magnitude and direction of the distance between points on the target area which produce reflections that travel in phase to the observation location; varying the spatial relation between the observation location and the target area and/or the given radiation frequency, in order to establish a plurality of different observation states which succeed one another in time, each state being associated with a distinct combination of magnitude and direction of the distance between points on the target area which produce reflections that travel in phase to the observation location; producing two coherent radiation beams, directing the two beams onto a receiving plane provided with an array of radiation receiving cells and storing output signals from each receiving cell, and controlling the two beams, for each observation state in succession, such that the two collimated beams have: beam axes which are inclined relative to one another by an angle corresponding in magnitude and direction to the magnitude and direction representations; a phase difference corresponding to the phase difference between the transmitted and received radiation; and intensities such that the product of the intensities of the two beams corresponds to the intensity product of the transmitted and received radiation.

Image synthesis using time sequential holography

A method and apparatus for producing an image of a target area, by: at an observation location spaced from the target area, transmitting a beam of electromagnetic radiation toward the target area, and receiving reflections of the radiation from the target area; providing a representation of the magnitude and direction of the distance between points on the target area which produce reflections that travel in phase to the observation location; varying the spatial relation between the observation location and the target area and/or the given radiation frequency, in order to establish a plurality of different observation states which succeed one another in time, each state being associated with a distinct combination of magnitude and direction of the distance between points on the target area which produce reflections that travel in phase to the observation location; producing two coherent radiation beams, directing the two beams onto a receiving plane provided with an array of radiation receiving cells and storing output signals from each receiving cell, and controlling the two beams, for each observation state in succession; such that the two collimated beams have: beam axes which are inclined relative to one another by an angle corresponding in magnitude and direction to the magnitude and direction representations; a phase difference corresponding to the phase difference between the transmitted and received radiation; and intensities such that the product of the intensities of the two beams corresponds to the intensity product of the transmitted and received radiation.

Optical systems are disclosed which are capable of generating and rapidly changing time delays of electrical signals for true time delay beam formation and beam steering and for signal processing applications. The systems utilize an interferometer configuration. A first optical modulator in a first leg of the interferometer is used to modulate coherent light with the signal to be delayed. In a second leg of the interferometer, a second optical modulator provides beam steering to a prism stack, which produces a set of plane reference waves having a range of orientations required to generate a desired range of time delays. Preferably the optical modulators are acousto optic Bragg cells. Alternatively, a stack of lens pairs or diffractive optical elements or a holographic optic element may be used in place of the prism stack. The modulated optical signal from the first leg interferes on an array of photodiodes with the reference waves from the second leg. The resulting electrical signals out of the photodiodes are delayed replicas of the signals driving the optical modulator in the first leg.

Time delay beam formation

Sequential image synthesizer

Disclosed are acousto-optical information processors employing a two-dimensional, time-integrating architecture. These three-product type processors are multi-purpose processors which can perform a variety of complex signal processing operations in two-dimensions, without requiring two-dimensional spatial light modulators. Typical of these processing operations are two-dimensional correlation, spectrum analysis, and cross ambiquity function processing. Some of the two-dimensional processing operations are made possible by the incorporation into a two-dimensional correlator of a distributed local oscillator, which may be implemented with mechanical-optical or electro-optical techniques. The acousto-optical processors may be easily implemented with readily available optical and acousto-optical components.

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Columbia, MD, United States of America

Terry M Turpin