A communication interface comprising a host with non-linear equalizers configured to perform non-linear equalization. Also part of the interface is a host to optic module channel electrically connecting the host to an optic module and the optic module. The optic module comprises a transmitter and a receiver. The transmitter includes a linear equalizer and an electrical to optical module configured to convert the equalized signal from the driver to an optical signal, and transmit the optical signal over a fiber optic cable, such that the transmitter does not perform non-linear processing. The receiver includes a photodetector, configured to convert the received optic signal to a received electrical signal, and a linear amplifier configured to perform linear amplification on the received electrical signal. A driver sends the amplified received signal over an optic module to host channel, such that the receive does not perform non-linear processing.

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.

Cost-effective high-data-rate optical data transceivers are presented, comprising an electronic analog transversal filter simultaneously providing one or more of bandwidth compensation and forward impairment compensations for the transmitted optical signal.

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(), 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(). 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(), 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(b). 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.

An equalizer device includes: an optical matrix switch including a first terminal group including at least two first terminals and a second terminal group including at least two second terminals; an equalizer group including at least two equalizers, an input end of each of the equalizers being connected to one of the second terminals included in the second terminal group, and an output end of each of the equalizers being connected to one of the first terminals included in the first terminal group; a variable attenuator being connected to the second terminal in a last stage included in the second terminal group and attenuating an input optical signal; and controller that changes a connection state between the first terminal and the second terminal, and sets an amount of attenuation in the variable attenuator.

A receiver (e.g., for a 10G fiber communications link) includes an interleaved ADC coupled to a multi-channel equalizer that can provide different equalization for different ADC channels within the interleaved ADC. That is, the multi-channel equalizer can compensate for channel-dependent impairments. In one approach, the multi-channel equalizer is a feedforward equalizer (FFE) coupled to a Viterbi decorder, for example, a sliding block Viterbi decoder (SBVD); and the FFE and/or the channel estimator for the Viterbi decoder are adapted using the LMS algorithm.

Methods and systems for waveguide delay based equalization with optical splitting in optical communication may include an optoelectronic circuit comprising an input waveguide, a directional coupler, an optical delay, photodetectors, a current mirror, and a transimpedance amplifier. The optoelectronic circuit may receive an input optical signal via the input waveguide, split the input optical signal into first and second output signals using the directional coupler, delay the first output signal using the optical delay, convert the delayed first output signal to a first electrical signal using a first photodetector, convert the second output signal to a second electrical signal using a second photodetector, amplify the second electrical signal using the current mirror, and sum the first and second electrical signals at inputs of the transimpedance amplifier to generate an output voltage.

A system for data transmission has a transmitter and a receiver connected by an optical channel. The transmitter has a transmitter laser and a transmitter-side electroabsorption modulator with an optical output. An electrical data input of the transmitter is connected to an electrical modulation terminal of the transmitter-side electroabsorption modulator. The receiver has a receiver laser and a receiver-side electroabsorption modulator with an optical output forming the input of the receiver. An electrical data output of the receiver is connected to the electrical modulation terminal of the receiver-side electroabsorption modulator. The transmitter and receiver lasers are detunable by specification of a physical variable, each provided by a respective control unit. The control units are synchronized and they specify the same signal at their outputs for establishing the physical variable for establishing the laser frequency.

It are provided an optical communication system and an optical communication method. The system comprising at least two optical channels for communicating optical data signals; at least one optical filter arrangement for compensating distortions of the optical data signals communicated via the optical channels and/or crosstalk between the optical channels. The optical filter arrangement comprises at least one optical filter assigned to one of the optical channels and at least one optical filter assigned to the other one of the optical channels, wherein each one of the optical filters is configurable in such a way that different wavelength components of an incoming optical signal will be modified individually.