A broadband light source apparatus, and corresponding method, includes a broadband light source configured to provide broadband source light characterized by a source wavelength spectrum. The apparatus also includes a broadband optical filter including both a polarization changer with a length, as well as an exit polarizer. The broadband optical filter receives the source light and delivers broadband output light characterized by an output wavelength spectrum that is a function of the source wavelength spectrum and the polarization changer length and has an output centroid wavelength. The polarization changer length is configured to minimize a thermal sensitivity of the output centroid wavelength. The filter can be configured in view of a particular source wavelength spectrum to thermally stabilize the centroid wavelength and to maximize relative integrated output power passively with respect to ambient temperature fluctuations.

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.

The present disclosure provides an optical equalizer for photonics system in an electric-optical communication network. The optical equalizer includes an input port and an output port. Additionally, the optical equalizer includes a filter having a number of stages coupled to each other in a multi-stage series with an output terminal of any stage being coupled to an input terminal of an adjacent next stage while the input terminal of a first stage of the multi-stage series being coupled from the input port. Each stage includes a tap terminal configured to pass an optical power factored by a coefficient of multiplication from the corresponding input terminal of the stage to a tap-output path characterized by a corresponding phase delay. Furthermore, the optical equalizer includes a combiner configured to sum up the optical powers respectively from the number of tap-output paths of the multi-stage series to the output port.

Various polarization rotator splitter (PRS) configurations are disclosed. In an example embodiment, a system includes a PRS that includes a silicon nitride (SiN) rib waveguide core that includes a rib and a ridge that extends vertically above the rib, the SiN rib waveguide core having a total height h.sub.SiN from a bottom of the rib to a top of the ridge, a rib height h.sub.rib from the bottom of the rib to a top of the rib, a rib width w.sub.rib, and a top width w.sub.SiN of the ridge. The rib width w.sub.rib varies along at least a portion of a length of the SiN rib waveguide core.

In an optical waveguide element, an optical waveguide is formed on a substrate, the optical waveguide has a main waveguide that propagates signal light, a waveguide for unnecessary light that guides unnecessary light released from the main waveguide, and a waveguide for collecting unnecessary light to which the unnecessary light emitted from the waveguide for unnecessary light is introduced, the waveguide for unnecessary light is connected to the waveguide for collecting unnecessary light via a waveguide for connection, and a width of the waveguide for connection, which is a width in a direction that perpendicularly intersects a propagation direction of the unnecessary light, at a portion connected to the waveguide for collecting unnecessary light is set to be wider than a width at a portion connected to the waveguide for unnecessary light with the waveguide for connection.

Disclosed herein is an optical waveguide element that includes a substrate and a waveguide layer formed on the substrate and comprising lithium niobate. The waveguide layer has a slab part having a predetermined thickness and a ridge part protruding from the slab part. The maximum thickness of the slab part is 0.05 times or more and less than 0.4 times a wavelength of a light propagating in the ridge part.

A photonic chip has at least one input waveguide, at least one output waveguide, one of at least one Mach-Zehnder interferometer and at least one resonator, and a one-sided optical port enabling in and out coupling of light where the input waveguide begins and the output waveguide ends.

An optical semiconductor device comprises a semiconductor substrate, an optical 90-degree hybrid circuit provided on the substrate, a plurality of input optical waveguides provided on the substrate, and a plurality of output optical waveguides provided on the substrate. The plurality of input optical waveguides is optically coupled to input ends of the optical 90-degree hybrid circuit. The plurality of output optical waveguides is optically coupled to output ends of the optical 90-degree hybrid circuit. Each of the plurality of input optical waveguides includes a first curving portion and a first straight portion adjacent to the first curving portion, and each of the plurality of output optical waveguides includes a second curving portion. A central axis of the first curving portion is inwardly offset with respect to a central axis of the first straight portion, and a central axis of the second curving portion follows a raised sine curve.

According to an example aspect, there is provided an apparatus comprising a first optical converter coupled to a fiber interface and to two waveguides, a dual rail encoder configured to encode dual rail form light from the two waveguides with payload information, and wherein the dual rail encoder is coupled to the first optical converter or to a second optical converter disposed between the dual rail encoder and the fiber interface, and wherein the first optical converter or the second optical converter is coupled so as to provide polarization encoded light into the fiber interface.

A monolithic photonic integrated circuit includes a platform, a monolithic laser formed in/on the platform, and an electro-optic polymer modulator monolithically built onto the platform and optically coupled to the monolithic laser. The polymer modulator is optically coupled to the monolithic laser by waveguides including electro-optic polymer waveguides. The electro-optic polymer modulator and the electro-optic polymer waveguides including an electro-optic polymer core and top and bottom electro-optic polymer cladding layers. The electro-optic polymer core having an electro-optic coefficient (r.sub.33) greater than 250 pm/v, and a Tg 150 C. to 200 C., and the top and bottom electro-optic polymer cladding layers having a Tg approximately the same as the Tg of the electro-optic polymer core.