A system may include a first module at a far end, and an optical fiber coupled to the first module. The system may also include a second module at a near end that is configured to generate and transmit instructions to the first module to control operation of the first module.

An integrated circuit that includes an optical receiver is described. This integrated circuit may include an optical receiver. The optical receiver may include a photodiode that receives an optical signal and that outputs a corresponding current. Moreover, the optical receiver may include an inductor that is electrically coupled to the photodiode. Furthermore, the optical receiver may include a resistive analog front-end stage that is electrically coupled to the inductor. Note that the inductor may have a resistance per unit length that is greater than a first threshold value (such as 40 m/m), and the inductor may be approximately dispersion-less. For example, a Q factor for inductive peaking associated with the inductor is less than a second threshold value (such as 5).

The present invention is directed to data communication system and methods. More specifically, various embodiments of the present invention provide a communication interface that is configured to transfer data at high bandwidth using PAM format(s) over optical communication networks. A feedback mechanism is provided for adjusting the transmission power levels. There are other embodiments as well.

An optical receiver includes photodetectors each provided on a corresponding channel of multiple channels and configured to detect an optical signal at the corresponding channel, a delay adjuster circuit provided before the photodetectors and configured to adjust a delay time of an optical waveform of an incoming signal on at least one channel, and a processor that controls the delay time such that a change point of a first optical waveform of a first channel is away from a data decision timing of a second optical waveform of a second channel, using information acquired from an electrical signal produced after photo-detection.

An example optical receiver may have an optical receiver front-end, four slicers, and a logic block. The optical receiver front-end may include a transimpedance amplifier to convert a photodiode output signal to a voltage signal. Three of the slicers may be data slicers, and one of the slicers may be an edge slicer. The slicers may each: shift the voltage signal based on an offset voltage set for the respective slicer, determine whether the shifted voltage signal is greater than a threshold value and generate a number of comparison signals based on the determining, and generate multiple digital signals by demuxing the comparison signals. The logic block may perform PAM-4 to binary decoding based on the data signals output by the data slicers and clock-and-data-recovery based on the digital signals output by the edge slicer.

A method and apparatus are provided for compensating incoming signals in a receiver of an optical fiber communication system for degradation due to nonlinear optical effects in the transmission channel. The compensation is performed, inter alia, in circuitry to compute perturbation terms that are representative of predicted optical nonlinearity of the transmission channel, and circuitry to combine the perturbation terms with soft data symbols obtained from an input signal stream. The computation of the perturbation terms involves circuitry for converting an input stream of soft data symbols to an input stream of hard data symbols, and then operating on the input stream of hard data symbols according to a model of nonlinear effects in the transmission channel.

An optical transmission apparatus (100) generates a second bit sequence B by encoding a first bit sequence b having forward error correction coding performed on a transmission bit sequence, maps the second bit sequence to a transmission symbol signal, and transmits an optical modulated signal generated by modulating an optical carrier wave into the transmission symbol signal. A symbol output unit (2020) generates a received symbol signal by demodulating an optical modulated signal received by an optical reception apparatus (2000). A first computation unit (2040) computes LLR(Bi) which is a log-likelihood ratio (LLR) of each bit Bi of the second bit sequence, using the received symbol signal. A second computation unit (2060) computes a log-likelihood ratio LLR(bi) of each bit bi of the first bit sequence from the LLR(Bi). A correspondence relationship between each bit of the first bit sequence and each bit of the second bit sequence is used in this computation. A decoding unit (2080) decodes the transmission bit sequence using the LLR(bi).

Disclosed is a baud rate tracking and compensation apparatus comprising: a clock generating component generating a clock; a sampling circuit sampling a reception signal according to the clock and thereby generating a sampled result, and the sampling circuit generating a transition notification signal when the sampled result indicates a transition of the reception signal; a clock counting circuit counting cycles of the clock between a first transition of the reception signal and a second transition of the reception signal according to the clock and the transition notification signal; a bit counting circuit counting bit(s) between the first transition and the second transition according to the clock and a bit cycle; and a calculation circuit dividing the number of the cycles by the number of the bit(s) to obtain a calculation value, and then updating the bit cycle according to the calculation value.

An optical data circuit includes threshold adjustment circuits to perform threshold adjustment compensation of asymmetrical optical noise. The optical data circuit includes an optical-to-electrical conversion circuit configured to produce first and second differential electrical data signals, at respective first and second electrical nodes, in response to an optical data signal. First and second digital-to-analog converter (DAC) circuits are each respectively coupled to the first and second electrical nodes and configured to respectively generate first and second adjustment signals. The first and second DAC circuits are configured to adjust the first and second differential electrical data signals such that a zero-crossing point of positive data is pulled up in response to the first adjustment signal and a zero-crossing point of negative data is pulled down in response to the second adjustment signal.

The present application relates to a wireless signal decoding method, which is used to decode an electric signal converted from a wireless signal, where the decoding method includes the following steps: recording a duration of each level of the electric signal; calculating an average value of m maximum durations and an average value of n minimum durations, where m and n are positive integers and are determined by referring to a distribution percentage value of first binary bit values and a distribution percentage value of second binary bit values in data respectively; calculating a decision duration according to the first average value and the second average value; comparing the duration of each level with the decision duration, and according to a comparison result, determining a binary bit value represented by the level; and integrating all binary bit values to restore the data represented by the electric signal.