Abstract: The present method is for generating a 4-level optical signal and it includes providing a continuous wave CW optical source; modulating the CW optical source with a first intensity modulator driven by a binary electrical signal a n Gbits/s to generate an optical signal; employing a second intensity modulator as a pulse carving modulator that is driven by an RF signal at n GHz thereby generating a 4 level optical signal for subsequent detection by a receiver.

Abstract: Aspects of the present disclosure are directed to the mitigation of multi-path interference from quasi-single-mode fiber using hybrid span configuration and digital signal processing wherein a hybrid span of quasi-single mode fibers and single-mode fibers are used to configure the hybrid span. Additional aspects are directed to introducing a low-baud rate sub-banding signal to reduce the number of DD-LMS taps required when compensating the multi-path interference as the low-baud rate signal requires fewer taps to cover a given range of MPI as compared to a high-baud rate signal. Finally further aspects are directed to an ALMS equalizer which further reduces the number of equalizer taps by shifting its center tap towards the right if higher-order modes transmit slower than a fundamental mode, otherwise the center tap is shifted to the left.

Abstract: A method and system for remote sensing using optical orbital angular momentum (OAM)-based spectroscopy for lateral motion detection. The method includes applying an OAM mode on a light beam to generate an OAM light beam, the OAM light beam having an optical OAM spectrum, applying an OAM optical beam tilt on the OAM light beam to generate a tilted OAM light beam, transmitting the tilted OAM light beam on a remote object, such that the remote object interacts with the tilted OAM light beam, receiving a reflected OAM spectrum associated with the remote object, the reflected OAM spectrum having power values of OAM modes on opposite sides of an OAM launch mode, and displaying lateral motion of the remote object based on the reflected OAM spectrum by comparing the power values.

Abstract: An optical communication method includes converting an optical pulse amplitude modulation (PAM) signal to a square QAM signal using an optical delay interferometer (DI) to perform all-optical PAM to QAM conversion in the DI; performing optical de-correlation of I and Q tributaries of the QAM signal to avoid frequency dependent attenuation in RF cabling which impacts signal quality; and finding optimal phase control mechanism of the DI by monitoring and equalizing down-converted I and Q electrical signal amplitudes, using coherent detection; and emulating a square quadrature amplitude modulation (QAM) optical signal with duplicated data copies.

Abstract: A controller for generating higher fiber spectral efficiency without using high-order modulation formats includes operating an interleaved bidirectional transmission IBT with sub-Nyquist optical regime exchange reach for spectral efficiency.

Abstract: A method by an optical network unit ONU includes, for downstream transmission, using a first tunable laser for coherent detection on a sub-band basis to increase receiver sensitivity and reduce analog-to-digital conversion ADC and digital signal processor DSP requirements within the ONU, and for upstream transmission, using a second tunable laser and using an optical signal beating between the first and second tunable lasers to generate a tunable radio frequency RF signal source for upstream multi-band OFDMA signal generation thereby avoiding need for an otherwise more costly RF clock source within the ONU, enabling low-speed digital-to-analog conversion DAC operation and rendering the ONU colorless in both optical and radio frequency RF domains.

Abstract: Methods and systems for transmission and reception of ternary phase-shift keyed data that include mapping triplets of binary bits to pairs of ternary symbols, such that three bits of data are encoded across two symbols having three-point constellations; modulating the pairs of ternary symbols onto a carrier; and transmitting the modulated carrier across a transmission medium.

Abstract: An optical communication method includes converting an optical pulse amplitude modulation (PAM) signal to a square QAM signal using an optical delay interferometer (DI) to perform all-optical PAM to QAM conversion in the DI; performing optical de-correlation of I and Q tributaries of the QAM signal to avoid frequency dependent attenuation in RF cabling which impacts signal quality; and finding optimal phase control mechanism of the DI by monitoring and equalizing down-converted I and Q electrical signal amplitudes, using coherent detection; and emulating a square quadrature amplitude modulation (QAM) optical signal with duplicated data copies.

Abstract: Systems and methods are disclosed to perform nonlinear compensation (NLC) in an optical communication system by applying digital backpropagation (DBP) using a frequency-shaped split-step Fourier method (FS-SSFM), and processing a data block using an overlap-and-save method with a block size M and an overlap factor of N samples between adjacent blocks.

Abstract: An optical switch includes an array of parallel few-mode fibers stacked vertically; beam stretchers that modifies an aspect ratio between a height and a width of beams associated with each few-mode fiber; a spatial light modulator with a 2D array of independently programmed tunable pixels, wherein the spatial light modulator manipulates phase and/or amplitude at each position of an incident optical beam; a wavelength demultiplexer which can separate the spectral components of an incident beam in angle; and lenses for imaging the modes of the input array of fiber to the spatial light modulator.

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: Systems and methods for amplification are shown that include a pump preparation module configured to provide a pump output that includes a plurality of pump modes; an amplification module configured to accept a multimode signal input and the pump output, such that the pump output causes an amplification of a plurality of modes in the signal input to produce an amplified signal output; and a gain control module configured to adjust a balance of the plurality of pump modes in the pump output to produce a predetermined amplified signal output.

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: Disclosed herein are methods, structures and systems for few-mode fiber (FMF) transmission including an optical amplifier exhibiting modal gain control suitable for such transmission in which higher order modes are amplified. An exemplary evaluation system is described and results presented.

Abstract: An optical receiver system is disclosed. The system includes a local oscillator, a mixer and a processor. The local oscillator is configured to generate a laser signal to indicate a selection of one of a plurality of channels. In addition, the mixer is configured to receive signals on the plurality of channels and to utilize the laser signal to distinguish the signal on the selected channel. Further, the processor is configured to maximize a power level difference between the laser signal and at least one of the plurality of channels based on a total number of the plurality of channels by adjusting the power of the laser signal input to the mixer to limit a noise penalty in the receiver system.

Abstract: The present method is for generating a 4-level optical signal and it includes providing a continuous wave CW optical source; modulating the CW optical source with a first intensity modulator driven by a binary electrical signal a n Gbits/s to generate an optical signal; employing a second intensity modulator as a pulse carving modulator that is driven by an RF signal at n GHz thereby generating a 4 level optical signal for subsequent detection by a receiver.

Abstract: Optical superchannel methods and systems that couple two or more local oscillators into a single coherent receiver front end to receive multiple optical subcarriers are shown and described. With multiple local oscillators coupled into a single coherent receiver and appropriate optical selective filtering of the superchannel signal, non-neighboring subcarriers may be received by the single coherent optical receiver.

Abstract: A method by an optical network unit ONU includes, for downstream transmission, using a first tunable laser for coherent detection on a sub-band basis to increase receiver sensitivity and reduce analog-to-digital conversion ADC and digital signal processor DSP requirements within the ONU, and for upstream transmission, using a second tunable laser and using an optical signal beating between the first and second tunable lasers to generate a tunable radio frequency RF signal source for upstream multi-band OFDMA signal generation thereby avoiding need for an otherwise more costly RF clock source within the ONU, enabling low-speed digital-to-analog conversion DAC operation and rendering the ONU colorless in both optical and radio frequency RF domains.

Abstract: Systems and methods are disclosed to perform nonlinear compensation (NLC) in an optical communication system by applying digital backpropagation (DBP) using a frequency-shaped split-step Fourier method (FS-SSFM), and processing a data block using an overlap-and-save method with a block size M and an overlap factor of N samples between adjacent blocks.

Abstract: Systems and methods for amplification are shown that include a pump preparation module configured to provide a pump output that includes a plurality of pump modes; an amplification module configured to accept a multimode signal input and the pump output, such that the pump output causes an amplification of a plurality of modes in the signal input to produce an amplified signal output; and a gain control module configured to adjust a balance of the plurality of pump modes in the pump output to produce a predetermined amplified signal output.