Abstract: A photon emitter including a photon generator configured to generate photons having a first polarization state or a second polarization state, the first polarization state being orthogonal to the second polarization state; and a time delay device which delays photons having the second polarization state with respect to those having the first polarization state.

Abstract: Receivers and methods are provided for polarization mode dispersion compensation in multi-level coded-modulation schemes using a BLAST algorithm and iterative polarization cancellation. A receiver includes a vertical Bell Laboratories Layered Space-Time Architecture (V-BLAST) orthogonal frequency division multiplexing (OFDM) detector configured to receive input sequences and partially cancel polarization interference with respect to the input sequences to output symbol estimates for the input sequences. The receiver further includes one or more low-density parity-check (LDPC) decoders coupled to the V-BLAST OFDM detector configured to receive channel bit reliabilities and output code words. The channel bit reliabilities are indirectly calculated from the symbol estimates. The one or more LDPC decoders iteratively provide extrinsic soft information feedback to the V-BLAST OFDM detector to compensate for the polarization interference.

Abstract: Methods and apparatus are described for modulating an optical signal using electroabsorption in conjunction with an optical interferometer. Phase-shift keying modulation can be achieved with lower amplitude modulator drive signals than conventional methods by splitting the signal to be modulated into multiple optical modes and interferometrically combining the modes after modulating at least one of the modes with an EAM. Using the present invention, the extinction ratio performance of ASK can be significantly improved for a given drive voltage or a desired extinction ratio can be achieved with a substantially lower drive voltage. Hence, the elecro-optic bandwidth of EAMs can be enhanced by overcoming the trade-off relationship between extinction ratio and bandwidth. Furthermore, the present invention can be used to generate other modulation formats, such as QPSK or QAM, with much lower drive voltages, thereby reducing the cost and power consumption of the high-speed drive electronics for the modulation.

Abstract: A communications and data link jamming system employs a fiber-optic RF delay line to provide rapid responses to threat signals. A sample of the RF signal threat environment is stored within the delay line, and a jamming video signal is added to the stored sample by modulation as it is being extracted from the delay line. The extracted signal is re-circulated back into the delay line, thereby effectively stretching the sample for highly efficient jamming. The jamming system is effective in countering burst communications and in defeating multiple simultaneous threat signals.

Abstract: The embodiments disclosed herein relate an insertable shield clip for use in controlling electromagnetic interference in an optical transceiver module. The optical transceiver module may include a shell that houses first and second optical subassemblies and an enclosure that cooperates with the shell in defining a covering for the optical transceiver module. The shield clip may comprise a body composed of conductive material. The body may include first and second vertical side members. The body may also include first and second shield members that are each configured to receive a corresponding nosepiece of one of the first and second optical subassemblies. The body may further include a bottom member that interconnects the first and second vertical side members and the first and second shield members.

Abstract: A laser warning receiver (LWR) to detect a very low power laser beam for a laser beam rider and provide a high angular resolution in determining the angle-of-arrival of that beam. An aperture having a fixed field-of-view (FOV) is located in a detection channel followed by a narrow-band filter and a detector whose output is applied to a pulse analyzer circuit. A localization channel with the same FOV has a similar narrow-band filter and a lens to focus light from that FOV onto a detector through a N×M element LCD matrix, an output of that detector being applied to the pulse analyzer circuit whose output is applied to a LCD pattern selector connected to the matrix which controls elements in the matrix to provide a transparent window of variable size and position. The size and position of that window allows a laser beam to reach the detector, the window being iterative reduced in size when a beam is detected to provide the location of its source.

Abstract: A control loop detects the presence of cross-talk between first, second and third adjacent amplitude modulated wavelength division modulated channels of an optical communications system. A receiver including a demultiplexer, such as an Arrayed Waveguide Grating (AWG), receives portions of the energy in the channels to derive first, second and third electrical signals that are respectively replicas of the modulation of the first, second and third channels. Wavelength drift of the carried frequencies of the channels in detected by comparing the three signals in an electronic combinatorial logic unit.

Abstract: Method and system for band blocking in an optical telecommunication network. According to an embodiment, the present invention provides a system for optical network. The system includes an input that is configured to receive an input signal through a first optical input. The system also includes a band splitting module that is coupled to the input. The band splitting module is configured to separate the input signal into a plurality of bands. The plurality of bands includes a first band and a second band. The first band includes a first plurality of wave channels. The first plurality of wave channels is characterized by a first channel spacing. The second band includes a second plurality of wave channels, which is characterized by a second channel spacing.

Abstract: An agile, high-power, reliable DIRCM system that is easily extended to address sophisticated UV or UV-visible capable multi-band threats includes a missile warner having missile warning receivers (MWRs), one or two-color suitably in the mid-IR range, that detect likely missile launch and pass the threat coordinates to a pointer-tracker having a Roll/Nod gimbal on which the IR laser transmitter is mounted. The pointer-tracker slews the gimbal to initiate tracking based on the threat coordinates and then uses its detector to continue to track and verify the threat. If the threat is verified, the pointer-tracker engages the laser to fire and jam the missile's IR seeker. By slewing the gimbal based on unverified threat coordinates to initiate tracking the system is highly agile and can respond to short and near simultaneous MANPADS shots.

Abstract: A Quantum Dense Coding System. The system includes a source, a transmitter and a receiver. The source is capable of down-converting a pump photon into a signal photon and an idler photon and outputting probability amplitudes, the signal photon and the idler photon, wherein the signal photon and the idler photon have an equal probability of outputting to a transmission channel and a reception channel. The transmitter is capable of receiving probability amplitudes, signal photons and idler photons from the transmission channel; and selectively changing vertical and horizontal phases of probability amplitudes of signal photons and idler photons; and outputting probability amplitudes, signal photons and idler photons. The receiver is capable of receiving probability amplitudes, signal photons and idler photons from the reception channel and the transmitter; and identifying vertical and horizontal phase changes created by the transmitter. A method for the system is also described.

Abstract: This application describes use of an opto-electronic feedback in oscillators to suppress phase noise based on the high Q factor of the opto-electronic feedback.

Abstract: A WDM optical transmission system is provided that operates at a plurality of channel wavelengths. The system includes at least three nodes at which any one or more of the channel wavelengths can be added or dropped. At least three optical transmission links interconnect the nodes. Each link includes a single waveguide over which travel oppositely-directed WDM signals having channel wavelengths that are interleaved with one another in a pairwise manner. A majority of the optical transmission links each have an optical span loss that corresponds to a level of coherent crosstalk between a reflected channel at a given wavelength co-propagating with a channel at the given wavelength prior to isolating one of the adjacent channels in a node that is less than a level of coherent crosstalk that would otherwise arise if a unidirectional transmission format were employed over a single waveguide in the same system.

Abstract: An apparatus and method of line coding to mitigate collision induced errors in Wavelength Division Multiplexing (WDM) optical communications systems is disclosed. The apparatus and method prevents Soliton-Soliton-Collision induced errors by reducing a variance in a number of possible collisions between solitons in multiple channels in a WDM fiber optic communication system using a sliding window criterion. The sliding window criterion defines a set of parametric values based on physical properties of the transmission network, a transmission frequency and a defined data block size. N-bit codes are iteratively selected and sequentially assigned to segments of a mapping table indexed by all possible unique combinations of “1”s and “0”s in a block of data. Input data blocks are mapped to corresponding code words having a reduced number of transitions for transmission on the fiber optic network. Received code words are converted back to a data stream corresponding to the input data stream.

Abstract: An interference-reducing optoelectronic device determines the value of a current data bit in an optical data stream. A receiver receives the optical data stream, which is converted to a series of samples by a D/A converter. A set of adaptive filters, each filter corresponding to a unique possible value for one or more prior data bits, filters the series of samples utilizing variable tap coefficients to generate filtered output values. The variable tap coefficients are at least partially different than the variable tap coefficients of another adaptive filter. Comparators compare the filtered output values against filter-specific adaptive threshold values to generate tentative values for the current data bit. A delay mechanism delays a determined value for the prior data bits, and a selection mechanism determines the value of the current data bit by selecting the tentative value corresponding to the delayed determined value of the prior data bits.

Abstract: A differential phase shift keyed demodulator system uses a Michelson interferometer configuration in which polarization maintenance is accomplished by using a single 50:50 coupler coupled to a first Faraday rotator mirror and a second Faraday rotator mirror through a first fiber and a second fiber, respectively. In this way, system passively eliminates the polarization problem caused by using a Mach-Zehnder interferometer.

Abstract: N-slit interferometry is applied to generate at least one optical signal representative of an alphabetical or numerical character, symbol, or the like. In particular, the present invention relates to an optical communication system for generating an interferometric character, comprising: a light source emitting a beam of coherent light directed along an optical path; a detector disposed in the optical path; a transmission grating disposed in the optical path intermediate the light source and the digital detector, and a multiple-prism beam expander disposed in the optical path intermediate the light source and the transmission grating adapted to illuminate the transmission grating to generate an interferometric pattern on the detector, the interferometric pattern being representative of the character.

Abstract: A chromatic-dispersion compensator comprises a plurality of dispersive elements (Q in number. Q≧2) each exhibiting a dispersion characteristic D (&lgr;) that varies substantially as a polynominal function of wavelength, the polynominal function being of an order (P−2) greater than 0, the dispersion characteristics being displaced in wavelength relative to each other such that the compensator has a net Pth-order dispersion characteristic DP that is non-zero and does not vary substantially with wavelength over an operating bandwidth.

Abstract: A method of reducing interference in a data stream includes filtering the data stream using a first equalizer to output a first filtered data stream. Also, the data stream is filtered using a second equalizer to create a second filtered data stream. Then, one or more error rates based on the first filtered data stream and the second filtered data stream are determined. Based at least in part on those error rates, a filtered data stream is selected from among the first filtered data stream and the second filtered data stream. A threshold value is determined, and then compared against the selected filtered data stream to generate a data bit.

Abstract: An interference-reducing optoelectronic device determines the value of a current data bit in an optical data stream. A receiver receives the optical data stream, which is converted to a series of samples by a D/A converter. A set of adaptive filters, each filter corresponding to a unique possible value for one or more prior data bits, filters the series of samples utilizing variable tap coefficients to generate filtered output values. The variable tap coefficients are at least partially different than the variable tap coefficients of another adaptive filter. Comparators compare the filtered output values against filter-specific adaptive threshold values to generate tentative values for the current data bit. A delay mechanism delays a determined value for the prior data bits, and a selection mechanism determines the value of the current data bit by selecting the tentative value corresponding to the delayed determined value of the prior data bits.

Abstract: The present invention provides an improved switchable interleaved channel separator device. The switchable interleaved channel separator device utilizes an adjustable reflective non-linear interferometer, which performs both switching and wavelength polarization sorting functions, so that overall complexity of the device is reduced. Further, because the adjustable non-linear interferometer is a reflection element, signal light paths are folded back upon one another so as to realize an overall reduction in the device's size, as well as the capability of performing optical couplings predominantly or wholly at a single side or at adjacent sides of the device.

Abstract: A control loop detects the presence of cross-talk between first, second and third adjacent amplitude modulated wavelength division modulated channels of an optical communications system. A receiver including a demultiplexer, such as an Arrayed Waveguide Grating (AWG), receives portions of the energy in the channels to derive first, second and third electrical signals that are respectively replicas of the modulation of the first, second and third channels. Wavelength drift of the carried frequencies of the channels in detected by comparing the three signals in an electronic combinatorial logic unit.

Abstract: A bidirectional optical link has a plurality of wavelengths to carry information in first and second differing transmission directions to optimize system performance. First and second sets of wavelengths of the plurality of wavelengths are determined wherein the wavelengths of the first set alternate with the wavelengths of the second set. Transmitting is performed in the first transmission direction by way of the first set of wavelengths and in the second transmission direction by way of the second set of wavelengths whereby the transmission directions of adjacent wavelengths of the plurality of wavelengths differ. The wavelengths of the plurality of wavelengths are wavelength division multiplexed within the optical link and the wavelengths transmitted in the same direction are multiplexed with each other. The wavelengths of the plurality of wavelengths can be substantially evenly spaced apart from each other or adjacent wavelengths transmitted in different directions may overlap.