One example includes an optical transmitter system. The system includes a waveguide to receive and propagate an optical signal. The system also includes a ring modulation system comprising a ring resonator that is optically coupled to the waveguide and is to resonate a given wavelength of the optical signal in response to an input data signal that is provided to a modulation amplifier to provide carrier injection to change a refractive index of the ring resonator to resonate the given wavelength of the optical signal to modulate the optical signal. The system further includes a tuning controller associated with the ring modulation system. The tuning controller can implement iterative feedback tuning of the ring modulation system based on a relative amplitude of an optical intensity of the given wavelength in the ring resonator and a variable reference amplitude to substantially stabilize the ring resonator with respect to the given wavelength.

An apparatus includes an optical device to output a data-modulated optical signal, an electrical radio-frequency (RF) driver to drive the optical device with one or more RF drive signals, a photodetector to provide a measure of a light intensity output by the optical device, and an electronic controller. The electronic controller is configured to dither an amplitude of at least one of the one or more RF drive signals at a dithering frequency. The electronic controller is also configured to adjust one or more operation settings of at least one of the electrical RF driver and the optical device based on a component of the measure of a light intensity at the dithering frequency.

The present invention is directed to optical communication systems and methods thereof. In various embodiments, the present invention provides method for linearizing Mach Zehnder modulators by digital pre-compensation and adjusting the gain of the driver and/or the modulation index. The pre-compensation can be implemented as a digital pre-compensation algorithm, which is a part of an adaptive feedback loop. There are other embodiments as well.

An optical communications apparatus comprising a host (100) and an optical module (200) comprising a Mach-Zehnder modulator (202), MZM, wherein the optical module is removably connected to the host via a connection path, the optical communications apparatus comprising: a signal generator (101) at the host, configured to generate a plurality of calibration signals at a plurality of frequencies; a host interface (102) configured to transmit the calibration signals to the optical module via the connection path; a module interface (201) configured to receive the transmitted calibration signals; wherein the MZM is configured to use the calibration signals to modulate a laser light source (206) and biased to a point at which average output power is proportional to the output modulated signal; an optical detector configured to measure an average magnitude of an output of the MZM when each of the calibration signals is used to modulate the laser light source; one of a host calibration unit (103) and a module calibration unit (203), configured to determine a magnitude response of the connection path based on the measured average magnitudes and magnitudes of the respective calibration signals, and further configured to determine a pre-emphasis characteristic based on the magnitude response, the pre-emphasis characteristic for application to signals transmitted by the optical transmitter in use.

An optical device may include a transmitter to provide an optical signal via a set of channels and a modulator. The optical device may include two or more tributary modulators to modulate the set of channels with a training pattern. The optical device may include a set of optics to alter a first channel relative to a second channel of the set of channels. The optical device may include a detector to determine an optical power measurement of the optical signal after the first channel is altered relative to the second channel. The optical device may include a controller to generate a control signal to adjust a power balance associated with the optical signal based on the optical power measurement. The optical device may include a controller to provide the control signal to a tributary modulator to alter a modulation of the optical signal.

An optical transmission device includes an optical modulator and a processor. The optical modulator optically modulates an optical signal with a driving signal to output a modulated optical signal. The processor performs ABC on a bias of the optical modulator, using the modulated optical signal, so as to cause the bias to converge to an optimum point. The processor starts the ABC using a modulated optical signal optically modulated with a QPSK signal at start-up timing, acquires an optimum value that is a bias value when the bias converges to the optimum point, and stops the ABC. After the ABC is stopped, the processor sets the acquired optimum value as an initial value, and restarts the ABC using a modulated optical signal optically modulated with an N-QPSK signal.

Optoelectronic oscillator systems and an optoelectronic oscillator noise reduction method. One example of an optoelectronic oscillator system includes an optical source positioned at a first end of a fiber-optic path, the optical source being configured to transmit an optical signal along the fiber-optic path, an optical modulator positioned to receive and modulate the optical signal based on at least a reference signal, a retro-reflector positioned at a second end of the fiber-optic path, the retro-reflector being configured to receive and retro-reflect the optical signal, the retro-reflected optical signal having at least a frequency range of inherent fiber noise canceled, and an optical circulator positioned along the fiber-optic path between the optical modulator and the retro-reflector, the optical circulator being configured to direct the optical signal to the retro-reflector and direct the retro-reflected optical signal along a feedback path to a first photodetector to generate the reference signal.

The present invention is directed to optical communication systems and methods thereof. In various embodiments, the present invention provides method for linearizing Mach Zehnder modulators by digital pre-compensation and adjusting the gain of the driver and/or the modulation index. The pre-compensation can be implemented as a digital pre-compensation algorithm, which is a part of an adaptive feedback loop. There are other embodiments as well.

An optical modulator includes an optical splitter splitting input optical signals into a first optical signal and a second optical signal and transmitting the first optical signal and the second optical signal to a first optical waveguide and a second optical waveguide, respectively, an optical combiner generating an output optical signal by combining the first and second optical signals transmitted from the first and second optical waveguides respectively, and including three output ports including a main output port, a first auxiliary output port, and a second auxiliary output port, three output optical waveguides connected to the three output ports, respectively, and transmitting the output optical signal, and an optical detector connected to at least one of the three output optical waveguides.

An optical device may include a transmitter to provide an optical signal via a set of channels and a modulator. The optical device may include two or more tributary modulators to modulate the set of channels with a training pattern. The optical device may include a set of optics to alter a first channel relative to a second channel of the set of channels. The optical device may include a detector to determine an optical power measurement of the optical signal after the first channel is altered relative to the second channel. The optical device may include a controller to generate a control signal to adjust a power balance associated with the optical signal based on the optical power measurement. The optical device may include a controller to provide the control signal to a tributary modulator to alter a modulation of the optical signal.