Equalizer for an optical transmission system

摘要

An equalizer (60) processes, in the electrical domain, a signal obtained from a path of an optical transmission system. The equalizer comprises N cascaded stages (where N≧1). At least one of the stages comprises a cascade of a linear equalization element (61) and a non-linear equalization element (62). The equalizer (60) is able to compensate for both linear impairments, such as dispersion, and non-linear impairments. The cascaded linear and non-linear elements can simulate the effect of signal propagation through a fiber which has the opposite propagation parameters (e.g. attenuation, dispersion, non-linearity) to those of the propagation path experienced by a signal in the transmission system. The non-linear equalization element (62) can be a non-linear phase rotator which rotates phase of an input signal proportional to the squared modulus of the input signal amplitude. The linear equalization element (61) can comprise a digital filter, such as an Infinite Impulse Response (HR) filter or a Finite Impulse Response (FIR) filter.

主权项

1. An equalizer for processing, in a digital electrical domain, a signal obtained from a path of an optical transmission system, the equalizer disposed in a digital signal processor and comprising a plurality of cascaded stages, where at least two of the plurality of cascaded stages each comprise a cascade of:
a linear equalization element; and a non-linear equalization element, the linear equalization element and the non-linear equalization element each comprising adjustable parameters, wherein the digital signal processor is configured to monitor a performance parameter of the equalizer and to control values of the adjustable parameters to optimize the performance parameter, wherein the non-linear equalization element is a non-linear phase rotator, and wherein the linear equalization element compensates for dispersion and the non-linear equalization element compensates for nonlinearity in each of the at least two of the plurality of cascaded stages.