Abstract: An apparatus includes an input receiving a modulated optical data signal having components of at least first and second polarizations, a first optical detector receiving the data signal, the first optical detector being first polarization-selective or first polarization-sensitive, passing components of the data signal having the second polarization, and outputting a first electrical signal, a second optical detector coupled to the first optical detector to receive the components of the data signal having the second polarization, and outputting a second electrical signal, and a processor applying a Kramers-Kronig process to the first and second electrical signals, and outputting the data signal using the Kramers-Kronig processed first and second electrical signals.

Abstract: An apparatus includes an input receiving a modulated optical data signal having components of at least first and second polarizations, a first optical detector receiving the data signal, the first optical detector being first polarization-selective or first polarization-sensitive, passing components of the data signal having the second polarization, and outputting a first electrical signal, a second optical detector coupled to the first optical detector to receive the components of the data signal having the second polarization, and outputting a second electrical signal, and a processor applying a Kramers-Kronig process to the first and second electrical signals, and outputting the data signal using the Kramers-Kronig processed first and second electrical signals.

Abstract: The invention presents an equalizing device, a corresponding method and an optical signal with a frame structure for enabling the method. The equalizing device includes a first 2×2 MIMO equalizer configured to perform a first equalization on the digital signal, supported by a 2×2 MIMO channel estimation of the channel based on the digital signal. Further, the device includes a second 2×2 MIMO equalizer, arranged after the first equalizer and configured to perform a second equalization on the digital signal, supported by a State of Polarization (SOP) estimation of the optical signal based on the digital signal.

Abstract: A phase-locked loop for a differential recovery of the clock signal wherein an extracted data signal (DS) is conveyed via a phase delay element and thence to a phase comparator. In the phase comparator comparison signals, whose phase shifts can be set relative to one another, differential phase evaluation is carried out. This results in a control signal (RS) whose operating point, independent of the power of the transmit channel, always lies in the center of the control range. In the inventive differential timing recovery, the dependencies on power fluctuations, signal-to-noise ratio, the pulse shape and on transmitted bit patterns are eliminated to the greatest possible extent.