An optical transmission and reception system includes an optical transmitter that converts an electrical data signal into an optical signal and transmits the optical signal; and an optical receiver that receives the optical signal input from the optical transmitter via an optical transmission line and converts the optical signal into the data signal. The optical transmitter includes a first compensator that compensates for a loss generated in the optical transmitter based on a first coefficient and a second coefficient, and the optical receiver includes a second compensator that compensates for a loss generated in the optical transmission line based on a third coefficient.

A system can include an optical receiver. The optical receiver can have an optical delay component and at least one electrical component (e.g., diode, resistor and/or transistor) operatively coupled to (e.g., integrated within) the optical delay component. The system can further include a processing device, operatively coupled to a memory, that can tune an amount of optical delay implemented by the optical delay component in a low loss and/or low dispersion manner. For example, the processing device can adjust, based on optical delay tuning data (e.g., built-in self-test (BIST) data), the at least one electrical component to modify at least one property of the at least one optical delay component.

In one embodiment, an intensity modulated (IM) direct detection (DD) optical receiver using a photonic integrated circuit (PIC) with an array of semiconductor optical amplifiers (SOAs) for flexible chromatic dispersion compensation (CDC) is provided. The PIC comprises an 1:N optical splitter to split an input optical signal into N copies; an array of N semiconductor optical amplifiers (SOAs) to receive the N optical outputs from the optical splitter; an array of optical delay lines to receive the outputs from the N SOAs, wherein the delay coefficients for the array of optical delay lines are {0, T, 2T, . . . (N−1) T}, where T=½B, where B is the system symbol rate, and each optical path with odd index (1, 3, 5, . . . N−1) from the N optical paths includes a 90-degree phase-shifter; and an optical N:1 coupler to re-combine all N optical paths. A method for automatically controlling a PIC based on the feedback signal from the Rx DSP in an optical receiver is also provided.

In one embodiment, an intensity modulated (IM) direct detection (DD) optical receiver using a photonic integrated circuit (PIC) with an array of semiconductor optical amplifiers (SOAs) for flexible chromatic dispersion compensation (CDC) is provided. The PIC comprises an 1:N optical splitter to split an input optical signal into N copies; an array of N semiconductor optical amplifiers (SOAs) to receive the N optical outputs from the optical splitter; an array of optical delay lines to receive the outputs from the N SOAs, wherein the delay coefficients for the array of optical delay lines are {0, T, 2T, . . . (N−1) T}, where T=½B, where B is the system symbol rate, and each optical path with odd index (1, 3, 5, . . . N−1) from the N optical paths includes a 90-degree phase-shifter; and an optical N:1 coupler to re-combine all N optical paths. A method for automatically controlling a PIC based on the feedback signal from the Rx DSP in an optical receiver is also provided.

An apparatus and method to monitor a polarization change by inserting pilot signals in a transmission signal and converting the pilot signals in the receiving signal from a Jones space into a Stokes space. A velocity of a polarization change of the optical link is estimated by using the Stokes vectors of the pilot signals, thereby directly and accurately estimating the polarization change of the optical link. Moreover, estimation of the velocity of the polarization may be applicable where rotation of state of polarization and polarization-dependent loss coexist in an optical link.

An apparatus and method to monitor a polarization change by inserting pilot signals in a transmission signal and converting the pilot signals in the receiving signal from a Jones space into a Stokes space. A velocity of a polarization change of the optical link is estimated by using the Stokes vectors of the pilot signals, thereby directly and accurately estimating the polarization change of the optical link. Moreover, estimation of the velocity of the polarization may be applicable where rotation of state of polarization and polarization-dependent loss coexist in an optical link.

An optical modulation system comprises a signal source configured to generate an amplitude modulated electrical signal having a bandwidth and divided into frequency components comprising at least a first frequency component covering a first portion of the bandwidth and a second frequency component covering a second portion of the bandwidth; and an electro-optic modulator for receiving an input optical signal, the modulator having a first optical path and a second optical path, the input optical signal being divided between the first optical path and the second optical path and recombined after propagation along the first optical path and the second optical path to produce an output optical signal, and at least one of the first optical path and the second optical path comprising a phase shifter comprising a pair of electrodes in which each electrode is configured to receive a driving signal; wherein the or each phase shifter is coupled to the signal source to receive at least one of said frequency components as a driving signal for an electrode, and the phase shifters are arranged such that the or each phase shifter receives a different pair of driving signals.

An optical modulation system comprises a signal source configured to generate an amplitude modulated electrical signal having a bandwidth and divided into frequency components comprising at least a first frequency component covering a first portion of the bandwidth and a second frequency component covering a second portion of the bandwidth; and an electro-optic modulator for receiving an input optical signal, the modulator having a first optical path and a second optical path, the input optical signal being divided between the first optical path and the second optical path and recombined after propagation along the first optical path and the second optical path to produce an output optical signal, and at least one of the first optical path and the second optical path comprising a phase shifter comprising a pair of electrodes in which each electrode is configured to receive a driving signal; wherein the or each phase shifter is coupled to the signal source to receive at least one of said frequency components as a driving signal for an electrode, and the phase shifters are arranged such that the or each phase shifter receives a different pair of driving signals.

An optical transmission/reception unit includes a carrier rotatable about a rotational axis, an optical receiver arranged at the carrier on the rotational axis to receive an optical reception signal from a first direction, an optical transmitter arranged adjacent to the optical receiver at the carrier to emit an optical transmission signal in a second direction, and a transmission/reception optic arranged at the carrier on the rotational axis above the optical receiver and extending across the optical receiver and the optical transmitter, wherein the transmission/reception optic includes a reception optic and a transmission optic arranged in the reception optic. The reception optic is configured to guide the optical reception signal incident on the transmission/reception optic towards the optical receiver on the rotational axis, and the transmission optic is arranged above the optical transmitter and is configured to shape the optical transmission signal emitted by the optical transmitter into an output beam.

An electric digital received signal obtained from a received optical signal is segmented into blocks of a certain length with an overlap of a length determined in advance with an adjacent block. Fourier transformation is performed for each of the blocks. The blocks subjected to the Fourier transformation are stored consecutively in time series, a coefficient determined based on a wavelength dispersion compensation amount according to one of frequency positions and a delay amount according to one of the frequency positions and one of time positions is applied to each of frequency component values included in a plurality of the stored blocks, and the blocks to which the coefficient has been applied and which are obtained by adding up the frequency component values to which the coefficient has been applied for each of the frequency positions are generated. Inverse Fourier transformation is performed on the generated blocks to which the coefficient has been applied. A part of the overlap subjected to the inverse Fourier transformation is removed.