Abstract: An optical modulator comprises, as optical modulator components, first and second transmitter chains and a first optical time division multiplex, OTDM, generator arranged to receive time interleaved optical pulses generated by one of said optical modulator components.

Abstract: An approach for pre-distorting an input signal for an optical transmitter so as to at least partially compensate in advance for linear and non-linear distortions of the optical transmitter is provided.

Abstract: An optical modulator comprises, as optical modulator components, first and second transmitter chains and a first optical time division multiplex, OTDM, generator arranged to receive time interleaved optical pulses generated by one of said optical modulator components.

Abstract: An approach for pre-distorting an input signal for an optical transmitter so as to at least partially compensate in advance for linear and non-linear distortions of the optical transmitter is provided.

Abstract: A self-calibration procedure for an optical transmitter is provided. During the self-calibration procedure, a phase bias of an optical modulator of the optical transmitter is set so that an in-phase path and a quadrature path of the optical modulator are in phase. Stimulus signals are supplied to the in-phase and quadrature paths of the optical modulator, over a frequency range. Detection, with a photodetector, is made of an optical output of the optical modulator at a plurality of frequency steps over the frequency range. A photodetector converts an optical output of the optical modulator to an electrical signal. First and second measurement values are generated from the electrical signal output from the photodetector. A frequency spectrum and/or time delay is computed from the first and second measurement values for each frequency step value over the frequency range.

Abstract: Embodiments of the present disclosure provide techniques and an apparatus for partitioning calibration data into line card and pluggable properties and processing the partitioned data using a processor of the line card. For example, calibration information corresponding to components in the pluggable module may be stored on the pluggable module and transferred from the pluggable optical module to the processor on the line card. The processor may combine the calibration information received from the optical module with calibration information corresponding to properties on the line card to obtain system calibration information. The system calibration information may be used to configure one or more components used to process electric signals sent to or received from the optical module.

Abstract: A system includes a laser configured to generate a tunable optical frequency. The system also includes an optical transmitter to map baseband data to symbols represented in a digital modulation constellation, add a frequency offset to the digital modulation constellation to cause the digital modulation constellation to rotate at a rate equal to the added frequency offset, modulate the optical frequency with the rotating digital modulation constellation, and transmit the resulting modulated optical frequency. The system also includes an optical receiver to receive the transmitted modulated optical frequency and, using the tunable optical frequency, detect the rotating digital modulation constellation conveyed by the received modulated optical frequency.

Abstract: A system includes a laser configured to generate a tunable optical frequency. The system also includes an optical transmitter to map baseband data to symbols represented in a digital modulation constellation, add a frequency offset to the digital modulation constellation to cause the digital modulation constellation to rotate at a rate equal to the added frequency offset, modulate the optical frequency with the rotating digital modulation constellation, and transmit the resulting modulated optical frequency. The system also includes an optical receiver to receive the transmitted modulated optical frequency and, using the tunable optical frequency, detect the rotating digital modulation constellation conveyed by the received modulated optical frequency.

Abstract: In an optical receiver, an optical local oscillator (LO) frequency is generated. A modulated optical frequency is received at the optical receiver. An LO-signal frequency offset between the received modulated optical frequency and the optical LO frequency is determined. A determination is made as to whether the LO-signal frequency offset is in one of multiple predefined non-overlapping target windows that cover respective non-zero LO-signal frequency offsets. If it is determined that the LO-signal frequency offset is not in one of the target windows, the optical LO frequency is tuned to drive the LO-signal frequency offset toward one of the target windows to ensure the LO-signal frequency offset is non-zero.

Abstract: Embodiments of the present disclosure provide techniques and an apparatus for partitioning calibration data into line card and pluggable properties and processing the partitioned data using a processor of the line card. For example, calibration information corresponding to components in the pluggable module may be stored on the pluggable module and transferred from the pluggable optical module to the processor on the line card. The processor may combine the calibration information received from the optical module with calibration information corresponding to properties on the line card to obtain system calibration information. The system calibration information may be used to configure one or more components used to process electric signals sent to or received from the optical module.

Abstract: An optical signal is received at a coherent optical receiver. The received optical signal is converted to a first electrical signal and a second electrical signal through a first photodetector and a second photodetector, respectively. The first electrical signal is input into a first single input variable gain amplifier, and the second electrical signal is input into a second single input variable gain amplifier. A gain of at least one of the first single input variable gain amplifier or the second single input variable gain amplifier is controlled to balance the output of the first single input variable gain amplifier and the output of the second single input variable gain amplifier. The output of the first single input variable gain amplifier and the output of the second single input variable gain amplifier are input into a differential amplifier. A receiver output is obtained at an output of the differential amplifier.

Abstract: In one embodiment, a method includes receiving an optical input signal to be modulated by an IQ modulator. The method includes applying data to first and second modulators during a first operation, and applying a first pattern of data to the first modulator and a second pattern of data to the second modulator during a second operation. The second operation results in an optical output signal of the IQ modulator having a low power output and a high power output. The first and second patterns are defined to provide respective desired average powers for a predefined time period based on the low and high power outputs. In another embodiment, a method includes indentifying a transmitter in an optical system by low bit rate signaling. Low bit rate signaling includes receiving an optical input signal from an optical source and transmitting identification data of the transmitter.

Abstract: Embodiments of the present disclosure provide techniques and an apparatus for partitioning calibration data into line card and pluggable properties and processing the partitioned data using a processor of the line card. For example, calibration information corresponding to components in the pluggable module may be stored on the pluggable module and transferred from the pluggable optical module to the processor on the line card. The processor may combine the calibration information received from the optical module with calibration information corresponding to properties on the line card to obtain system calibration information. The system calibration information may be used to configure one or more components used to process electric signals sent to or received from the optical module.

Abstract: In an optical receiver, an optical local oscillator (LO) frequency is generated. A modulated optical frequency is received at the optical receiver. An LO-signal frequency offset between the received modulated optical frequency and the optical LO frequency is determined. A determination is made as to whether the LO-signal frequency offset is in one of multiple predefined non-overlapping target windows that cover respective non-zero LO-signal frequency offsets. If it is determined that the LO-signal frequency offset is not in one of the target windows, the optical LO frequency is tuned to drive the LO-signal frequency offset toward one of the target windows to ensure the LO-signal frequency offset is non-zero.

Abstract: Embodiments of the present disclosure provide techniques and an apparatus for partitioning calibration data into line card and pluggable properties and processing the partitioned data using a processor of the line card. For example, calibration information corresponding to components in the pluggable module may be stored on the pluggable module and transferred from the pluggable optical module to the processor on the line card. The processor may combine the calibration information received from the optical module with calibration information corresponding to properties on the line card to obtain system calibration information. The system calibration information may be used to configure one or more components used to process electric signals sent to or received from the optical module.

Abstract: An optical signal is received at a coherent optical receiver. The received optical signal is converted to a first electrical signal and a second electrical signal through a first photodetector and a second photodetector, respectively. The first electrical signal is input into a first single input variable gain amplifier, and the second electrical signal is input into a second single input variable gain amplifier. A gain of at least one of the first single input variable gain amplifier or the second single input variable gain amplifier is controlled to balance the output of the first single input variable gain amplifier and the output of the second single input variable gain amplifier. The output of the first single input variable gain amplifier and the output of the second single input variable gain amplifier are input into a differential amplifier. A receiver output is obtained at an output of the differential amplifier.

Abstract: An optical signal is received at a coherent optical receiver. The received optical signal is converted to a first electrical signal and a second electrical signal through a first photodetector and a second photodetector, respectively. The first electrical signal is input into a first single input variable gain amplifier, and the second electrical signal is input into a second single input variable gain amplifier. A gain of at least one of the first single input variable gain amplifier or the second single input variable gain amplifier is controlled to balance the output of the first single input variable gain amplifier and the output of the second single input variable gain amplifier. The output of the first single input variable gain amplifier and the output of the second single input variable gain amplifier are input into a differential amplifier. A receiver output is obtained at an output of the differential amplifier.

Abstract: An optical transmitter may include a sample rate converter and a digital-to-analog converter operable to convert an inputted digital electrical signal to an analog optical signal. The signal converter may include a first interface operable to receive a digital electrical signal that may include a block of input data having N symbols in a time domain. The signal converter may also include: a first module operable to transform, via a Fourier Transform, the input data having N symbols from the time domain to a frequency domain; a second module operable to up-sample the N frequency domain samples so that there are 1.6N, 2N, or 2.67N frequency domain samples, for example; and then a third module operable to transform, via an inverse Fourier Transform, the 1.6N, 2N, or 2.67N frequency domain samples to an equivalent number of time domain samples at 1.6, 2.0, or 2.67 samples per symbol, respectively.

Abstract: An apparatus and methods for generating multi-level output signals for use by an optical modulator are provided. The apparatus comprises a plurality of input signal lines each configured to receive a binary input signal, an output signal line and a plurality of amplifier stages. The amplifier stages are each connected between one of the input signal lines and the output signal line so as to each produce an output voltage on the output signal line of either a first level or a second level. The level of the output voltage is based on the binary signal at the respective input signal line, and the output voltages of the respective plurality of amplifier stages collectively produce a summed analog output voltage on the output signal line at two or more different levels each configured to drive an optical modulator.

Abstract: An optical signal is received at a coherent optical receiver. The received optical signal is converted to a first electrical signal and a second electrical signal through a first photodetector and a second photodetector, respectively. The first electrical signal is input into a first single input variable gain amplifier, and the second electrical signal is input into a second single input variable gain amplifier. A gain of at least one of the first single input variable gain amplifier or the second single input variable gain amplifier is controlled to balance the output of the first single input variable gain amplifier and the output of the second single input variable gain amplifier. The output of the first single input variable gain amplifier and the output of the second single input variable gain amplifier are input into a differential amplifier. A receiver output is obtained at an output of the differential amplifier.