A digital processor (DP) is configured to obtain a temporal sequence of digital phase distortion measurements of a first optical signal received by a coherent optical receiver (COR) from an optical fiber link, where the first optical signal co-propagates with a second, power-modulated, optical signal in different frequency channels. The DP is configured to estimate a cross-correlation between the temporal sequence of digital measurements and a temporal sequence of powers of the second optical signal for a plurality of relative time shifts between the sequences, and to identify a location along the optical fiber link based on a magnitude of the cross-correlation exceeding a threshold for a particular time shift.

A digital processor (DP) is configured to obtain a temporal sequence of digital phase distortion measurements of a first optical signal received by a coherent optical receiver (COR) from an optical fiber link, where the first optical signal co-propagates with a second, power-modulated, optical signal in different frequency channels. The DP is configured to estimate a cross-correlation between the temporal sequence of digital measurements and a temporal sequence of powers of the second optical signal for a plurality of relative time shifts between the sequences, and to identify a location along the optical fiber link based on a magnitude of the cross-correlation exceeding a threshold for a particular time shift.

A system and method for extending the path length of an electromagnetic wave signal traveling between apertures is disclosed. One such system may comprise N arrays having M.sub.1 through M.sub.N apertures, respectively, wherein N2, M.sub.12, and each of M.sub.2 through M.sub.N1, a substantial number of the M.sub.1 apertures in a first array is configured to send the electromagnetic wave signal to a substantial number of the M.sub.2 apertures in a second array through the M.sub.N apertures in a N-th array, the substantial number of the M.sub.2 apertures in the second array through the M.sub.N apertures in the N-th array receiving the electromagnetic wave signal from the substantial number of the M.sub.1 apertures in the first array is configured to redirect the received electromagnetic wave signal back to the substantial number of the M.sub.1 apertures in the first array, and the substantial number of the M.sub.1 apertures in the first array is further configured to send the electromagnetic wave signal to another one of the M.sub.1 apertures in the first array after receiving the redirected electromagnetic wave signal from a M.sub.N-th aperture in the N-th array.

A system and method for extending the path length of an electromagnetic wave signal traveling between apertures is disclosed. One such system may comprise N arrays having M.sub.1 through M.sub.N apertures, respectively, wherein N2, M.sub.12, and each of M.sub.2 through M.sub.N1, a substantial number of the M.sub.1 apertures in a first array is configured to send the electromagnetic wave signal to a substantial number of the M.sub.2 apertures in a second array through the M.sub.N apertures in a N-th array, the substantial number of the M.sub.2 apertures in the second array through the M.sub.N apertures in the N-th array receiving the electromagnetic wave signal from the substantial number of the M.sub.1 apertures in the first array is configured to redirect the received electromagnetic wave signal back to the substantial number of the M.sub.1 apertures in the first array, and the substantial number of the M.sub.1 apertures in the first array is further configured to send the electromagnetic wave signal to another one of the M.sub.1 apertures in the first array after receiving the redirected electromagnetic wave signal from a M.sub.N-th aperture in the N-th array.

A band division timing adjustment unit aligns timings of a plurality of signals, which are generated by dividing a received signal according to a plurality of frequency bands, in a time domain and combines the plurality of signals for which the timings have been aligned. A chromatic dispersion compensation unit compensates chromatic dispersion of an output signal of the band division timing adjustment unit for each of the plurality of frequency bands.

Communication of light signals and optical cables can be managed to mitigate error associated with using optical cables to communicate light signals. A communication management component (CMC) can embed respective timing synchronization pulses in respective lights signals having respective wavelengths. The light signals can be typical light signals or can be squeezed and twisted to generate a desired twisted light signal. The light signals can be transmitted via the optical cable to a receiver. A CMC, at the receiver end, can determine error associated with the transmission of the light signals via the optical cable and respective characteristics of the respective light signals, including respective arrival times of the respective timing synchronization pulses and respective light intensity or power levels of the respective light signals. From the respective characteristics, CMC can determine a compensation action to perform mitigate the error with regard to subsequent transmissions of light signals.

Communication of light signals and optical cables can be managed to mitigate error associated with using optical cables to communicate light signals. A communication management component (CMC) can embed respective timing synchronization pulses in respective lights signals having respective wavelengths. The light signals can be typical light signals or can be squeezed and twisted to generate a desired twisted light signal. The light signals can be transmitted via the optical cable to a receiver. A CMC, at the receiver end, can determine error associated with the transmission of the light signals via the optical cable and respective characteristics of the respective light signals, including respective arrival times of the respective timing synchronization pulses and respective light intensity or power levels of the respective light signals. From the respective characteristics, CMC can determine a compensation action to perform mitigate the error with regard to subsequent transmissions of light signals.

A receiver is configured to calculate a representation of a received signal conveying symbols at a frequency f.sub.S, the representation comprising non-zero components at frequencies of magnitudes exceeding f.sub.S/2. The receiver calculates a first term comprising a function of a phase difference between the representation at a first pair of frequencies separated by a gap and comprised within a first band of width 2 centered at f.sub.S/2, and a second term comprising a function of a phase difference between the representation at a second pair of frequencies separated by the gap and comprised within a second band of width 2 centered at f.sub.S/2, wherein <2, and wherein the higher frequency of the first pair and the higher frequency of the second pair are separated by the frequency f.sub.S. An estimate of chromatic dispersion in the received signal is calculated based on the first term and the second term.

A receiver is configured to calculate a representation of a received signal conveying symbols at a frequency f.sub.S, the representation comprising non-zero components at frequencies of magnitudes exceeding f.sub.S/2. The receiver calculates a first term comprising a function of a phase difference between the representation at a first pair of frequencies separated by a gap and comprised within a first band of width 2 centered at f.sub.S/2, and a second term comprising a function of a phase difference between the representation at a second pair of frequencies separated by the gap and comprised within a second band of width 2 centered at f.sub.S/2, wherein <2, and wherein the higher frequency of the first pair and the higher frequency of the second pair are separated by the frequency f.sub.S. An estimate of chromatic dispersion in the received signal is calculated based on the first term and the second term.

A system and method for extending the path length of an electromagnetic wave signal traveling between apertures is disclosed. One such system may comprise N arrays having M.sub.1 through M.sub.N apertures, respectively, wherein N2, M.sub.12, and each of M.sub.2 through M.sub.N1, a substantial number of the M.sub.1 apertures in a first array is configured to send the electromagnetic wave signal to a substantial number of the M.sub.2 apertures in a second array through the M.sub.N apertures in a N-th array, the substantial number of the M.sub.2 apertures in the second array through the M.sub.N apertures in the N-th array receiving the electromagnetic wave signal from the substantial number of the M.sub.1 apertures in the first array is configured to redirect the received electromagnetic wave signal back to the substantial number of the M.sub.1 apertures in the first array, and the substantial number of the M.sub.1 apertures in the first array is further configured to send the electromagnetic wave signal to another one of the M.sub.1 apertures in the first array after receiving the redirected electromagnetic wave signal from a M.sub.N-th aperture in the N-th array.