A cryogenic optoelectronic data link, comprising a sending module operating at a cryogenic temperature less than 100 K. An ultrasensitive electro-optic modulator, sensitive to input voltages of less than 10 mV, may include at least one optically active layer of graphene, which may be part of a microscale resonator, which in turn may be integrated with an optical waveguide or an optical fiber. The optoelectronic data link enables optical output of weak electrical signals from superconducting or other cryogenic electronic devices in either digital or analog form. The modulator may be integrated on the same chip as the cryogenic electrical devices. A plurality of cryogenic electrical devices may generate a plurality of electrical signals, each coupled to its own modulator. The plurality of modulators may be resonant at different frequencies, and coupled to a common optical output line to transmit a combined wavelength-division-multiplexed (WDM) optical signal.

Provided is a first bias power source that generates a first data bias voltage to be applied to an optical modulation unit for the I component, a second bias power source that generates a second data bias voltage to be applied to an optical modulation unit for the Q component, and a third bias power source that generates a quadrature bias voltage to be applied to an optical phase shifter, a data bias voltage adjustment unit that applies a feedback control to each of the first bias power source and the second bias power source, and a quadrature bias voltage adjustment unit that determines whether or not the quadrature bias voltage is optimal on a basis of a second optical QAM signal generated by an IQ optical modulator, and applies a feedback control to the third bias power source, in which a first optical QAM signal and the second optical QAM signal are generated by the IQ optical modulator but the optical phase difference between an optical electric field EI and an optical electric field EQ differs by π.

In a system for converting digital data into a modulated optical signal, an electrically controllable device, including a modulator having one or more actuating electrodes, provides an analog-modulated optical signal that is modulated in response to output data bits of a digital-to-digital mapping. A digital-to-digital conversion provides the mapping of input data words to the output data bits. The mapping enables adjustments to correct for non-linearities and other undesirable characteristics, thereby improving signal quality.

Embodiments of the present disclosure include optical transmitters and transceivers with improved reliability. In some embodiments, the optical transmitters are used in network devices, such as in conjunction with a network switch. In one embodiment, lasers are operated at low power to improve reliability and power consumption. The output of the laser may be modulated by a non-direct modulator and received by integrated optical components, such as a modulator and/or multiplexer. The output of the optical components may be amplified by a semiconductor optical amplifier (SOA). Various advantageous configurations of lasers, optical components, and SOAs are disclosed. In some embodiments, SOAs are configured as part of a pluggable optical communication module, for example.

An optical transmitter transmits a modulated optical signal in which each symbol carries M bits. M is an integer larger than one. The optical transmitter includes: a signal generation circuit configured to generate M×N binary electric signals based on transmission data, bit rates of the M×N binary electric signals being equal to each other, N being an integer larger than one, when the optical transmitter multiplexes N optical signals in time-division multiplexing; a Mach-Zehnder interferometer; and M×N phase-shift elements provided along an optical path of the Mach-Zehnder interferometer and respectively configured to shift phases of light propagated in the optical path corresponding to the M×N binary electric signals. The M×N phase-shift segments are comprised of N electrode groups. Each of the N electrode groups includes M or more electrodes to which corresponding M binary electric signals among the M×N binary electric signals are given.

A method for automatic power and modulation management in a communication network includes (a) generating a discontinuous management function that is a weighted function of at least spectral efficiency and power consumption of the communication network, (b) determining, from the discontinuous management function, an optimal modulation format, an optimal forward error correction (FEC) rate, and an optimal output power of a transmitter of the communication network, which collectively achieve a maximum value of the management function, and (c) causing the transmitter to operate according to the optimal modulation format, the optimal FEC rate, and the optimal output power.

Embodiments are disclosed for providing a serializer and/or a deserializer with redundancy using optical modulators. An example system includes an MZM structure that comprises a first waveguide interferometer arm structure and a second waveguide interferometer arm structure. The first waveguide interferometer arm structure comprises a first segmented electrode associated with at least a first electrode and a second electrode. The second waveguide interferometer arm structure comprises a second segmented electrode associated with at least a third electrode and a fourth electrode. The MZM structure is configured to convert an optical input signal into an optical output signal through application of a digital data signal to the first electrode and the third electrode, and application of a redundant digital data signal to the second electrode and the fourth electrode.

A first optical transceiver includes a transmission signal processor that generates a multi-valued pulse amplitude modulation signal including a fixed bit pattern. The first optical transceiver includes an optical transmitter that transmits the multi-valued pulse amplitude modulation signal as an optical transmission signal. The first optical transceiver includes an optical receiver that receives an optical adjustment signal from a second optical transceiver to reproduce an adjustment signal from the optical adjustment signal. The first optical transceiver includes a first controller that controls the transmission signal processor based on a bit error rate included in the optical adjustment signal to adjust light power at each level of the optical transmission signal.

A skew compensation system for a coherent optical communication network includes a transmitter modulator having a first driver input for receiving a first signal from a first channel, a second driver input for receiving a second signal from a second channel, a source input for receiving a continuous wave source signal, and a modulation output in communication with an optical transport medium of the network. The system further includes a tunable delay line disposed between the second channel and the second driver input for inserting a pre-determined training sequence onto the second signal prior to the second driver input, and a processor for determining a skew amount between the second signal at the second driver input and the first signal at the first driver input, calculating a pre-compensation value corresponding to the skew amount, and reducing the skew amount at the modulation output according to the pre-compensation value.

A method for automatic power and modulation management in a communication network includes (1) generating a management function of (a) mutual information per symbol (MIPS) of the communication network and (b) output power (P) of a transmitter of the communication network, determining a selected MIPS value and a selected P value which achieve a maximum value of the management function, and causing the transmitter of the communication network to operate according to the selected MIPS value and the selected P value.