A method/system described herein addresses the intrinsic nonlinearity of electrooptic modulators and the restrictions placed on the signals dynamic range in applications such as data communication and sensing. Linear electro-optic modulation utilizing ring resonator electrooptic modulators is produced over a dramatically wider range of the input signal amplitude, which improves the dynamic range and the amount of information that is transmitted via laser light. A distributed and subranging design folds the large dynamic range across multiple linear subranges, with each subrange being addressed using a unique optical wavelength, or a unique optical fiber, or a unique free space path. The subrange within the wide dynamic range of the input signal is captured by the linear portion of the transfer function of a single transfer function. This enables the efficient use of optical links for the transmission and processing of analog and multilevel signals, overcoming the limitations that were hindering progress.

Methods and systems for a polarization immune wavelength division multiplexing demultiplexer are disclosed and may include, in an optoelectronic transceiver having an input coupler, a demultiplexer, and an amplitude scrambler: receiving input optical signals via the input coupler, communicating the input optical signals to the amplitude scrambler via waveguides, configuring the average optical power in each of the waveguides utilizing the amplitude scrambler, and demultiplexing the optical signals utilizing the demultiplexer. The amplitude scrambler may include phase modulators and a coupling section. The phase modulators may include sections of P-N junctions in the two waveguides. The demultiplexer may include a Mach-Zehnder Interferometer. The demultiplexed signals may be received utilizing photodetectors. The input coupler may include a polarization splitting grating coupler. The average optical power may be configured above which demultiplexer control circuitry is able to control the demultiplexer to process incoming optical signals.

An optical transmission system includes: a terminal station device that transmits a wavelength multiplexed optical signal resulting from multiplexing an optical signal and dummy light; and an optical add-drop multiplexer that receives respective wavelength multiplexed optical signals transmitted from a plurality of the terminal station devices and performs add-drop processing on the wavelength multiplexed optical signals. The dummy light has a wavelength arrangement in which adjacent wavelengths are arranged with equal spacing, and the wavelength arrangement of the dummy light differs between the terminal station devices.

A method for transmitting an orthogonal function processed signal over a communications link on a fiber involves generating at least one mode crosstalk matrix illustrating mode crosstalk between transmitted modes and adjacent modes within the fiber. Adjacent modes to be multiplexed together are selected based on entries within the generated mode crosstalk matrix being less than or equal to a predetermined value. The transmitted modes and the selected adjacent modes are multiplexed together into the orthogonal function processed signal for transmission on the communications link on the fiber.

A system for optically down-converting a radio-frequency signal includes phase modulators in a push-pull configuration. Separately tuned optical bandpass filters pass through one or more harmonics and inverse harmonics based on the RF signal to produce a local oscillator. A balanced photo-detector receives a coherent interference signal and derives the down-converted local oscillator from a filtered harmonic and inverse harmonic.

Consistent with the present disclosure, data, in digital form, is received by a transmit node of an optical communication system, is processed and then output to drive a modulator. The modulator, in turn, modulates light at one of a plurality of wavelengths in accordance with the received data, forming a plurality of corresponding carriers. The plurality of wavelengths used for the plurality of carriers are spectrally spaced apart by a common, periodic fixed spacing. The plurality of carriers are optically combined with a fixed spacing combiner to form a superchannel. A plurality of superchannels are generated and then multiplexed together onto an optical communication path and transmitted to a receive node. Each superchannel includes a plurality of carriers, each spectrally separated by the same fixed spacing. The plurality of superchannels are spectrally separated by an amount corresponding to the fixed spacing of the plurality of carriers. At the receive node, the superchannels are optically demultiplexed, and the plurality of carriers of a respective superchannel are then supplied to a photodetector circuit, which receives additional light at one of the optical signal carrier wavelengths from a local oscillator laser. The resultant signals are then processed electronically to separate the individual carriers and output data corresponding to the input data.

The present invention provides an optoelectronic switch for transferring an optical signal from an input device to an output device, the optoelectronic switch including an array of interconnected switch modules, which are interconnected by an interconnecting fabric. The switch modules are arranged in an N-dimensional array, the ith dimension having a size Ri (i=1, 2, . . . , N), each switch module having an associated set of coordinates giving its location with respect to each of the N dimensions. Each switch module is a member of N such sub-arrays Si, each sub-array Si comprising Ri switch modules whose coordinates differ only in respect of their location in the ith dimension, and each of the N sub-arrays being associated with a different dimension.

In some embodiments, a system includes a set of servers, a set of switches within a switch fabric, and an optical device. The optical device is operatively coupled to the set of servers via a first set of optical fibers. Each server from the set of servers is associated with at least one wavelength from a set of wavelengths upon connection to the optical device. The optical device is operatively coupled to each switch from a set of switches via an optical fiber from a second set of optical fibers. The optical device, when operative, wavelength demultiplexes optical signals received from each switch from the set of switches, and sends, for each wavelength from the set of wavelengths, optical signals for that wavelength to the server from the set of servers.

An optical signal monitor, including: a storage that holds a threshold value set for each of determination areas having a bandwidth set in accordance with an average grid of dummy light; a measurement section that sequentially measures an optical intensity of an inputted wavelength-multiplexed optical signal with respect to each of measurement areas obtained by dividing the determination area into areas with a bandwidth sufficiently smaller than a grid width of a monitoring-target optical signal composing the wavelength-multiplexed optical signal, and output measured values; and a section that determines that dummy light corresponding to the determination area needs introducing if each of measured values in the determination area is smaller than a threshold value, and, determines that dummy light corresponding to the determination area does not need introducing if at least one of the measured values in the determination area is equal to or larger than the threshold value.

An optical transmission apparatus includes: a coherent detector configured to receive light including different polarization components from an optical transmission path, and perform coherent detection of received light including the different polarization components; an adaptive equalizer configured to adaptively equalize, by a digital filter, a complex electric signal for each of the polarization components obtained by the coherent detection, a gain value for controlling an amplitude of the complex electric signal being applied to the complex electric signal; and a polarization dependent loss monitor configured to determine a polarization dependent loss of the optical transmission path, based on a correction filter parameter obtained by correcting a filter parameter of the digital filter according to the gain value, the filter parameter being adaptively updated by an adaptive equalization of the adaptive equalizer.