A method of interference suppression with intermodulation distortion mitigation includes processing an RF signal comprising an RF signal of interest and an RF interfering signal to produce a first and second RF drive signal each with a desired RF interference signal power and having a 90 degree relative phase. The first RF drive signal is imposed onto a first optical signal with a modulator to generate a first modulated optical signal so that the modulator has a large-signal behavior that is characterized by a Bessel function of the first kind J.sub.1(ϕ), wherein the desired power at a frequency of the interference signal of the first drive signal is chosen to correspond to a zero of the Bessel function of the first kind J.sub.1(ϕ). The second RF drive signal is imposed onto a second optical signal with a modulator to generate a second modulated optical signal so that the modulator has a large-signal behavior that is characterized by a Bessel function of the first kind J.sub.1(ϕ), wherein the desired power at a frequency of the interference signal of the second drive signal is chosen to correspond to another zero of the Bessel function of the first kind J1(ϕ). The first and second modulated optical signal are combined with an optical power ratio that is selected to suppress third-order intermodulation distortion products in an electrical signal generated by detecting the optically combined first and second modulated optical signals.

A circuit and method for mitigating multi-path interference in direct detection optical systems is provided. Samples of an optical signal having a pulse amplitude modulated (PAM) E-field are processed by generating a PAM level for each sample. For each sample, the sample is subtracted from the respective PAM level to generate a corresponding error sample. The error samples are lowpass filtered to produce estimates of multi-path interference (MPI). For each sample, one of the estimates of MPI is combined with the sample to produce an interference-mitigated sample.

The present invention pertains to systems and methods for equalizing a digitally modulated input signal for transmission as an optical signal over an optical fiber. In detail, this equalization is accomplished prior to the signal's conversion to an optical signal, and prior to the signal being filtered by a vestigial sideband (VSB) filter. In particular, equalization is accomplished by giving weights to the taps of a tapped delay equalizer, wherein weights for respective taps are derived from the output signal after its conversion to a digital signal at the downstream end of the optical fiber.

The method includes receiving, at a first optical communication device, feedback information on training of a neural network from at least one second optical communication device, the neural network configured to process a signal received from the first optical communication device, the feedback information at least including a training performance indication for training of the neural network conducted at the at least one second optical communication device; updating, based on the feedback information, a first initial parameter value set for the neural network maintained at the first optical communication device, to obtain a second initial parameter value set for the neural network; and transmitting the second initial parameter value set to at least one further second optical communication device, for training of the neural network to be conducted at the at least one further second optical communication device based on the second initial parameter value set.

Aspects of the present disclosure describe single mode fiber distributed temperature sensing (DTS) with improved noise characteristics employing superluminescent emitting diodes (SLEDs) and/or amplified spontaneous emission (ASE) light sources.

All-optical multi-rate systems and methods include and use a continuous wave (CW) light source for providing a CW carrier signal, a plurality of modulators used for modulating the CW carrier signal to form a plurality of modulated optical signals, an inverse filter bank for multiplexing the plurality of modulated optical signals to form a multiplexed optical signal, and a post distortion filter (PDF) for obtaining a narrowed multiplexed optical signal and, optionally, for eliminating inter-symbol interference (ISI) in the narrowed multiplexed optical signal.

A circuit and method for mitigating multi-path interference in direct detection optical systems is provided. Samples of an optical signal having a pulse amplitude modulated (PAM) E-field are processed by generating a PAM level for each sample. For each sample, the sample is subtracted from the respective PAM level to generate a corresponding error sample. The error samples are lowpass filtered to produce estimates of multi-path interference (MPI). For each sample, one of the estimates of MPI is combined with the sample to produce an interference-mitigated sample.

Various example embodiments of the present disclosure relates to a physical layer, PHY, circuitry for an optical line terminal, OLT, the PHY circuitry being configured to receive a control signal including an identification of a transmitting ONT for pre-loading an equalization configuration associated with the identification of the transmitting ONT. Other example embodiments relate to a medium access control, MAC, circuitry for OLT, the MAC circuitry being configured to determine an upstream allocation map for optical network terminals, ONTs, and to generate a control signal for a PHY circuitry including synchronization information for receiving upstream optical signal bursts from a transmitting ONT and an identification of the transmitting ONT based on the upstream allocation map. Further example embodiments related to an optical line terminal, OLT, and a method therefor.

To suppress the deterioration of the characteristics of a MIMO equalizer as well as minimizing an increase in circuit size in spite of the occurrence of signal spectrum narrowing and asymmetric spectrum degradation, a wavelength-division multiplexing optical transmission system (10) according to an embodiment includes a transmitter (1) that generates one channel signal by wavelength-division multiplexing a plurality of subcarrier signals so as to overlap each other and transmits the channel signal, and a receiver (2) that separates a received channel signal into subcarrier signals, and performs equalization using an MIMO equalizer (3) including a FDE-MIMO equalizer (4) and a TDE-MIMO equalizer (5) on each of the separated subcarrier signals.

A receiver system is provided for receiving a coherent Pulse Amplitude Modulation (PAM) encoded signal. The receiver system may include an optical polarization component configured to modulate a polarization of the received coherent PAM encoded signal. The receiver system may further include a digital signal processor (DSP) configured to perform polarization recovery between the received coherent PAM encoded signal and the LO signal using a first control loop, and to perform phase recovery between the received coherent PAM encoded signal and the LO signal using a second control loop.