An optical multiplexer includes a plurality of light sources that emit a plurality of laser beams having different wavelengths, a collimator that collimates a plurality of laser beams emitted from a plurality of light sources, and a diffraction grating that diffracts a plurality of laser beams collimated by the collimator and emits a plurality of laser beams along a same optical path, the diffraction grating being of a transmission-type. A plurality of light sources are linearly arranged on an incident side focal plane of the collimator, a grating surface of the diffraction grating is disposed on an emission side focal plane of the collimator, and distance D between two adjacent light sources is set to satisfy D=f×(λ.sub.1−λ.sub.2)/p, where λ.sub.1, λ.sub.2 (λ.sub.1>λ.sub.2) are respectively wavelengths of laser beams emitted from the two adjacent light sources.

A wavelength converter includes: a first multiplexer that combines input signal light with wavelength-conversion excitation light; a second multiplexer that combines the signal light with Raman excitation light; a first nonlinear optical medium that generates wavelength-converted light of the signal light, based on a nonlinear optical effect; and a second nonlinear optical medium that amplifies wavelength-converted light of the signal light output from the first nonlinear optical medium. A wavelength of the Raman excitation light being a wavelength within an amplification band that allows Raman amplification of wavelength-converted light.

Described herein is a solution to address the intrinsic nonlinearity of analog signals and the restrictions this places on the signals dynamic range. The subject matter described herein produces linear electro-optic modulation over a dramatically wider range of the input signal amplitude. This is accomplished by a distributed multiwavelength design that folds the large dynamic range across multiple linear subranges, with each subrange being addressed using an optical wavelength. As a result, 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. Several physical implementations of this subject are presented herein. This innovation enables the efficient use of optical links for the transmission and processing of analog and multilevel signals, overcoming the limitations that were once hindering progress in this field.

Photonic devices, photonic integrated circuits, optical elements, and techniques of making and using the same are described. A photonic device includes an input region adapted to receive an optical signal including a multiplexed channel characterized by a distinct wavelength, a dispersive region optically coupled with the input region to receive the optical signal, the dispersive region including a plurality of sub-regions defined by an inhomogeneous arrangement of a first material and a second material, and a plurality of output regions optically coupled with the input region via the dispersive region. The plurality of sub-regions can include an input channel section, one or more coupler sections, and one or more branching sections. The plurality of sub-regions together can configure the photonic device to demultiplex the optical signal and to isolate the multiplexed channel at a first output region of the plurality of output regions.

An optical transmission device and an optical communication system being capable of coping with various installation forms of a transponder in a unit of optical fiber transmission path are provided. The optical transmission device is installed inside a station building. First and second interface units are connected to first and second fiber transmission paths accommodated in a submarine optical fiber cable. A first fiber transmission path mediates an optical signal to be transmitted between the first interface unit and a first transponder. A second fiber transmission path mediates an optical signal to be transmitted between the second interface unit and a second transponder.

The present disclosure provides a calibration system for wavelength-division multiplexing (WDM), a WDM system, and a calibrating method for WDM. The calibration system includes heating devices, an optical sensor, and an electrical device. When the optical sensor receives no beam with energy exceeding a threshold value from a first channel, the optical sensor transmits a first signal to the electrical device. In response to the first signal, the electrical device is configured to control the one or more of the heating devices to heat one or more of channels. When the optical sensor receives a beam having energy exceeding the threshold value from the first channel, the optical sensor transmits a second signal to the electrical device. In response to the second signal, the electrical device is configured to control the one or more of the heating devices to maintain the temperature of the one or more of the channels.

Photonic devices, photonic integrated circuits, optical elements, and techniques of making and using the same are described. A photonic device includes an input region adapted to receive an optical signal including a multiplexed channel characterized by a distinct wavelength, a dispersive region optically coupled with the input region to receive the optical signal, the dispersive region including a plurality of sub-regions defined by an inhomogeneous arrangement of a first material and a second material, and a plurality of output regions optically coupled with the input region via the dispersive region. The plurality of sub-regions can include an input channel section, one or more coupler sections, and one or more branching sections. The plurality of sub-regions together can configure the photonic device to demultiplex the optical signal and to isolate the multiplexed channel at a first output region of the plurality of output regions.

An integrated apparatus with optical/electrical interfaces and protocol converter on a single silicon substrate. The apparatus includes an optical module comprising one or more modulators respectively coupled with one or more laser devices for producing a first optical signal to an optical interface and one or more photodetectors for detecting a second optical signal from the optical interface to generate a current signal. Additionally, the apparatus includes a transmit lane module coupled between the optical module and an electrical interface to receive a first electric signal from the electrical interface and provide a framing protocol for driving the one or more modulators. Furthermore, the apparatus includes a receive lane module coupled between the optical module and the electrical interface to process the current signal to send a second electric signal to the electrical interface.

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.

A detection device for detecting polarization fluctuation of signal light having propagated through an optical transmission line includes: a differential phase information acquisition unit which acquires information indicating a differential phase of input light as an evaluation target at each of one or more time points; and a determination unit which determines whether the differential phase at at least some of the one or more time points satisfies a predetermined condition.