Abstract: Disclosed are structures and methods for generating a Nyquist superchannel.

Abstract: A computer implemented method for dynamically allocating traffic in a passive optical communication system includes employing an individual wavelength channel to carry different data services from an individual transmitter, configuring an optical network unit into optical network unit groups serving at least two community of users; and providing a flexible remote node with wavelength routing flexibility including switching wavelength traffic from optical network user groups with low capacity requirements to optical network user groups with increased wavelength traffic requirements.

Abstract: An optical communication system includes a digital signal processer coupled to the coherent receiver, said coherent receiver including a nonlinearity compensation module for compensating for nonlinear effects in fiber in the optical link for increasing capacity or transmission distance of the fiber, the nonlinearity compensation module includes a spectral slicing of the signal into bands, computing nonlinear interaction between the bands with parameters opposite to those of the fiber to reverse the non-linear effects in the fiber, and only certain nonlinear interactions between bands are considered thereby reducing complexity of the nonlinearity compensation.

Abstract: Disclosed are structures and methods for slicing a broadband signal into multiple, narrower bandwidth sub-bands through the use of a look-up table (LUT). An input broadband signal is first loaded by a pre-defined LUT. The LUT is designed with multiple parallel outputs, wherein each output is one individual sub-band.

Abstract: An optical access network with centralized digital optical line termination OLT including an optical line termination unit having a digital transmitter and a coherent receiver for downstream signal transmitting and upstream signal receiving, and at least one optical network unit ONU with transceiver functions for communicating with the OLT over an optical path, the ONU including intensity modulation and single photodiode detection, wherein the digital transmitter includes digital signal processing DSP, digital-to-analog conversion DAC and analog-to-digital conversion ADC functions that can be shared by all multiple ones of the ONU in the network, the DSP reducing or removing dispersion and non-linearity effects in the network and the coherent receiver enabling performance of the downstream stream signal transmitting to match that of the upstream signal receiving in the OLT.

Abstract: Disclosed are universal QPSK transmitter structures and methods for generating different QPSK signals exhibiting different polarization schemes, namely PolMux, PolMod and PolSw. The bit rate of the generated signals is variable, thereby allowing the transmitter to adjust to varying network traffic conditions. Advantageously, the generated signals may be detected by analog receivers (PolSw-QPSK) and coherent receivers (PolMux-QPSK, PolMod-QPSK, and PolSw-QPSK).

Abstract: A method for phase noise mitigation for a coherent receiver in either an OFDM or single carrier based transmission system including applying a frequency offset and coarse phase noise compensation based on a radio frequency RF tone or using a phase lock loop PLL m-th power procedure, responsive to a signal from a digital signal processed transmission with an added pilots signal over an optical system, applying fine phase noise compensation based on comparison of the pilots signal in a time domain, removing the pilots, and demodulating the remaining pilotless signal.

Abstract: A method for generating a 400 Gb/s single channel optical signal from multiple modulated subchannels includes carving respective modulated subchannels into return-to-zero RZ modulated subchannels having non-overlapping peaks with intensity modulators having a duty cycle less than 50%, and combining the subchannels into a single channel signal aggregating the bit rate of each of the subchannels. The subchannels are combined with a flat top optical component for increased subsequent receiver sensitivity.

Abstract: A computer implemented method for dynamically allocating traffic in a passive optical communication system includes employing an individual wavelength channel to carry different data services from an individual transmitter, configuring an optical network unit into optical network unit groups serving at least two community of users; and providing a flexible remote node with wavelength routing flexibility including switching wavelength traffic from optical network user groups with low capacity requirements to optical network user groups with increased wavelength traffic requirements.

Abstract: Disclosed are structures and methods for generating a Nyquist superchannel.

Abstract: Disclosed are structures and methods for slicing a broadband signal into multiple, narrower bandwidth sub-bands through the use of a look-up table (LUT). An input broadband signal is first loaded by a pre-defined LUT. The LUT is designed with multiple parallel outputs, wherein each output is one individual sub-band.

Abstract: Structures and methods of generating 8-QAM signals through the effect of a cascaded I/Q modulator and Mach-Zhender modulator. The 8-QAM signals are generated by applying one binary sequence to the dual-drive Mach-Zehnder modulator (MZM) and two binary sequences to the I/Q modulator. Operationally, the I/Q modulator generates QPSK constellation(s), while the dual drive MZM either maintains the QPSK constellation at an out ring, or attenuates its amplitude to the inner ring and rotates its phase by ?/4 phase depending on the binary data it was driven by.

Abstract: A method for optical layer traffic grooming includes receiving at least two optical input signals into respective optical receivers, each optical receiver having a photodetector for converting the respective optical input signal into a respective electrical signal; a grooming processor responsive to the electrical signals, the grooming processor being a radio frequency RF processor for processing the electrical signals at a subcarrier level to produce an RF orthogonal frequency division multiplexing signal OFDM signal; and modulating the groomed RF OFDM signal at a transmitter for conversion of the groomed RF OFDM into an optical signal.

Abstract: An energy efficient OFDM transceiver includes a transmitter using a decision processor to control first internal elements that can be operated in parallel and can be selectively powered off or hibernated, and a receiver using a processing decision element to control second internal elements that can be operated in parallel and can be selectively powered off or hibernated, wherein control of the first and second internal elements enables tracking status of network traffic, adjustment of OFDM bandwidth based on a traffic decision and selectively powering off or hibernating parallel ones of the first and second internal elements.

Abstract: An optical transmitter includes a dividing optical coupler, a first optical modulator driven by an I component of a first signal and a I component of a second signal for modulating a lightwave, a DC bias of the first optical, a second optical modulator driven by a Q component of the first signal and a Q component of the second signal for modulating a lightwave, a DC bias of the second optical modulator, a phase shifter, and a combining optical coupler for combining the modulated lightwave from the first optical coupler and the phase shifted Q components of the first and second signals for generating a quadrature amplitude modulated signal.

Abstract: Methods and systems for secure communication include assigning data streams to respective orthogonal sub-carriers according to random number information at a transmitter. The data streams are modulated onto the respective orthogonal sub-carriers before the orthogonal sub-carriers are transmitted. The random number information is transmitted on a second medium, separate from the transmission medium. The orthogonal sub-carriers are received from the transmission medium at a receiver, while the random number information is received from the second medium at the receiver. The orthogonal sub-carriers are associated with data streams using the random number information and demodulated to produce data for the associated data stream.

Abstract: Systems and methods are disclosed for a filter-less coherent receiving system with a filter-less coherent receiver frontend; a signal-signal beat-noise detector coupled to the filter-less coherent receiver frontend; and a real-time processor coupled to the filter-less coherent receiver frontend and the signal-signal beat-noise detector to reject signal-signal interference.

Abstract: A method includes producing interference between a received optical OFDM signal and an optical carrier extracted from the received optical OFDM signal to provide optical coherent detection of the received optical OFDM signal. Preferably, producing the interference includes optically splitting the received optical OFDM signal into a first part that is filtered to extract the carrier from the received optical OFDM signal and a second part similar to the received optical OFDM signal.

Abstract: Methods and devices for compensating for chromatic dispersion are shown that include receiving an input data signal, applying a filter to the data signal, and outputting a CD compensated signal. Applying the filter includes convolving known filter coefficients with a plurality of delayed versions of the data signal using addition and at least one inverse sign operation or using lookup tables and combining outputs to produce a CD compensated signal.

Abstract: A system and method are provided for carrier frequency offset (CFO) estimation for coherent optical orthogonal-frequency-division-multiplexing (CO-OFDM) broadband systems. The method includes obtaining an initial estimate of a normalized CFO with an estimation range equal to ±L/2 subcarrier subspacing using a single training symbol with L identical portions. The method further includes obtaining a maximum likelihood (ML) estimate of the CFO by performing a local grid search based on the initial estimate.