Abstract: Systems, devices and techniques for processing an optical signal transmitted from a source over a transmission medium having a length L and performing compensation of non-linear distortions include formulating the compensation as a digital back propagation algorithm by logically dividing the length L into N steps and compensating non-linear distortions for each step as a function of an attenuation adjusting constant parameter that can be selected from a range between 0.3 and 0.7.

Abstract: Systems, devices and techniques for processing received QPSK modulated optical signals include sampling the received signal at twice the baud rate, thereby producing samples that are then processed as 9-QAM symbols using a decision directed least squares optimization method. Data bits are then recovered from the resulting symbol estimates. The received optical signal may also include dual polarized signals for increased bandwidth capacity.

Abstract: We describe and demonstrate a novel and simple scheme to generate flattened optical subcarriers using only phase modulators driven by single frequency fundamental sinusoidal sources. 160.8 Gb/s PM-QPSK experiment over a single subcarrier has been demonstrated.

Abstract: A heterodyne optical signal detector and method performed thereby, the signal detector including an optical signal spectrum shaper operable to modify the shape of the frequency spectrum of a received optical signal, a laser local oscillator (LO), and polarization beam splitters (PBSs) to divide the signal and the LO into orthogonal components, waveguides in which intermediate frequency (IF) signals are formed, balanced photodetectors (BPDs) arranged to receive the IF signals and operable to convert the IF signals into electric signals, and analog to digital converters (ADCs) that digitize the electric signals.

Abstract: Aspects of a reconfigurable varactor array for providing a capacitance to control an output frequency of a voltage-controlled oscillator are provided. The reconfigurable varactor array can be configured to provide a configurable capacitance. The reconfigurable varactor array can include a plurality of varactor cells connected in parallel. The reconfigurable varactor array can also include a control circuit configured to receive a control signal to select the configurable capacitance from the reconfigurable varactor array. The control circuit can include a plurality of switch groups. Each switch group can be separately connected to one varactor cell in the reconfigurable varactor array. The control signal from the control circuit can control operation of each switch group.

Abstract: Optical signals with different orbital angular momentum (OAM) modes are used to multiplex data for different receiver together or a light signal. The OAM based multiplexing may be used in addition to other multiplexing schemes such as time division multiplexing, polarization multiplexing and so on. Capacity of existing optical network infrastructure can be increased significantly using OAM modulation, and data communication can be secured at the same time.

Abstract: A blind equalization technique of high-order QAM signals is provided. A method implemented at a receiver-side in an optical communication network receives an optical signal and performs a two-step polarization tracking process on the received optical signal. Using another method, a polarization multiplexed optical transmission is received by a receiver and a polarization tracking process is performed by applying two different algorithms in parallel. One algorithm may be a decision directed least means square (DD-LMS) algorithm. Another algorithm may be a constant modulus algorithm (CMA).

Abstract: Embodiments of the present invention pertain to optical wireless architecture, and in particular to novel optical architecture to provide wireless (mm)-wave signals and symmetrical wireline service with long-reach. Certain embodiments of the invention pertain to a novel method and apparatus to provide 12.5-Gb/s wireless signals at 60-GHz millimeter (mm)-wave and 100-Gb/s symmetrical wireline service with 80 km long-reach, for example. Moreover, novel enabling techniques are employed to overcome fiber dispersion, reduce costs, and provide super-broadband and long-reach service.

Abstract: A novel digital signal processing scheme (DSP) for quadrature duobinary (QDB) spectrum shaped polarization multiplexed quadrature phase shift keying (PM-QPSK) based on multi-modulus blind equalizations (MMBE) is proposed and demonstrated with both simulation and experimental results. The key algorithms for this novel digital signal processing scheme include the cascaded multi-modulus algorithm (CMMA) for blind polarization de-multiplexing, multi-modulus QPSK partitioning frequency offset estimation (FOE) and two stage carrier phase recovery (CPR) with maximum likelihood phase estimation. The final signal is detected by maximum-likelihood sequence detection (MLSD) for data BER measurement. The feasibility of the proposed digital signal processing scheme is demonstrated by the experiment of 112 Gb/s QDB spectrum shaped PM-QPSK signal with a 25 GHz bandwidth waveshaper for Nyquist WDM channels.

Abstract: An optical signal transmitting system, comprising: an optical transmitter including one or more input terminals and an output terminal; and a temporal polarization interleaver including an input terminal and an output terminal, wherein the output terminal of the optical transmitter is communicatively coupled to the input terminal of the temporal polarization interleaver, wherein: the optical transmitter is configured to receive one or more input signals through its one or more input terminals, generate an output signal using the one or more input signals, the output signal including a x-polarized tributary and a y-polarized tributary that is pulse-to-pulse aligned with the x-polarized tributary, and transmit the output signal to the temporal polarization interleaver; and the temporal polarization interleaver is configured to receive the output signal from the optical transmitter and cause a predefined phase delay to one of the x-polarized tributary and the y-polarized tributary.

Abstract: Systems, devices and techniques for receiving a signal comprising a quadrature duobinary modulated signal include performing channel equalization of the received signal using a constant multi-modulus to obtain a set of channel estimation coefficients and a stream of symbols, partitioning, based on modulus, the stream of symbols into three partitions, estimating carrier frequency based on the partitioned stream of symbols, recovering a phase of the signal using a maximum likelihood algorithm, and decoding the partitioned stream of symbols to recover data.

Abstract: A hood latch having an extra-long fishmouth for enabling a vehicle hood to deflect downwardly upon impact, such as when hit by a pedestrian in a frontal crash. To prevent this deflection when the hood is slammed shut in ordinary use, a stop lever is pivotally mounted to the latch housing. The stop lever features first and second arms defining a slot therein. One arm has a proboscis thereon and is biased to align the slot with the fishmouth, with the proboscis jutting into the fishmouth. The proboscis receives an impact from the striker and rotates the stop lever to a blocking position wherein the non-proboscis arm intercepts the striker and prevents it from reaching the bottom end of the fishmouth. In the closed position the ratchet retains the striker at an intermediate depth in the fishmouth, enabling the striker to travel toward the bottom end thereof.

Abstract: Modulation and demodulation of digital signals comprising symbols representing four or more bits uses a constellation map in which initial two bits of the modulated data identify a quadrant of the constellation map and the remaining bits of the modulated data identify a symbol within the quadrant corresponding to the four or more data bits. In some systems, the constellation map is made up from each successive two bits of the input data bits successively identifying a quadrant within a quadrant until a group of bits is uniquely mapped to a single symbol.

Abstract: A dual-polarization, 4-subcarriers orthogonal frequency division multiplexed signal carrying information bits is transmitted in an optical communication network without transmitting a corresponding pilot tone or training sequence. A receiver receives the transmitted signal and recovers information bits using a blind equalization technique and by equalizing the 4-subcarriers OFDM signal as a 25-QAM signal in time domain with a CMMA (constant multi modulus algorithm) equalization method.

Abstract: In an optical communication system, an optical transmitter changes operational physical layer parameters to meet future target throughput for the optical communication system. The optical transmitter communicates the upcoming change to the optical receiver in a message that used current physical layer parameters. The optical transmitter provides sufficient time to the optical receiver to adjust reception functions of the receiver, including polarization based demodulation scheme. In some implementations, the optical transmitter performs the transition to a new physical layer transmission format without waiting for an acknowledgement from the optical receiver.

Abstract: Embodiments of the present invention pertain to optical wireless architecture and, in particular, to novel optical architecture to provide fiber-optic and wireless communication systems, links, and access networks. Certain embodiments of the invention pertain to a novel method and apparatus to provide 109.6 Gb/s capacity over spans of 80-km SMF and 2×2 MIMO. Conversion of PM-QAM modulated wireless mm-wave signal to an optical signal as well as 80-km fiber transmission of the converted optical signal is also realized.

Abstract: Methods and devices are provided to facilitate production of optical signals that exhibit reduced crosstalk noise and intersymbol interference. In some configurations, a multi-stage optical interleaver, including a first and a second optical interleaver, is used to process a first and a second set of input optical channels. The composite optical output of the multi-stage interleaver includes the first set of optical channels and the second set of optical channels, where each of the first and second set of input optical channels is processed once by the first optical interleaver and once by the second optical interleaver. As such, the first and second sets of input optical channels are each filtered twice using only two optical interleavers.

Abstract: Aspects of the present invention include apparatus and methods for transmitting and receiving signals in communication systems. A multicarrier generator generates a multicarrier signal. An optical demultiplexer separates the multicarrier signal into separate multicarrier signals. At least one QPSK modulator modulates signals from the separate multicarrier signals. An optical multiplexer combines the QPSK modulated signals into a multiplexed signal. The multiplexed signal is then transmitted.

Abstract: Techniques for timing synchronization in an optical orthogonal frequency division multiplexing (OOFDM) system includes providing a time-domain training symbol having a symmetric distribution and producing the training symbol by transmitting a real-valued PN sequence on each subcarrier under the OOFDM. The training sequence includes an initial value, followed by an odd length palindromic sequence of values.

Abstract: Aspects of the present invention include devices and methods for receiving signals in communication systems. A partial response equalizer includes a full response linear equalizing device for equalizing a received signal; and a partial response post filter for post filtering the equalized signal. Aspects of the present invention devices and methods for coherently receiving signals in an optical communication system. A receiver front end converts a received partial response optical signal to a partial response digital signal. An equalizing device equalizes the pre-filtered full response digital signal. A full response carrier recovery device performs carrier recovery of the signal equalized by the equalizing device. A post-filter filters the signal having undergone carrier recovery by the full response carrier recovery device.