An optical waveguide crosspoint comprising first and second single multimode interference sections, each single multimode interference section comprising an input face, an output face and sidewalls extending therebetween, the distance between the input face and output face for each single multimode interference section being the; length of the multimode interference section, the lengths of the first and second multimode interference sections being L1 and L2 respectively; at least one primary input optical waveguide connected to the input face of the first single multimode interference section; at least one primary output optical waveguide connected to the output face of the first single multimode interference section; the first single multimode interference section comprising a symmetry axis extending from the center of the input face to the center of the output face; at least one secondary input optical waveguide connected to the input face of the second single multimode interference section; at least one secondary output optical waveguide connected to the output face of the second single multimode interference section; the second single multimode interference section comprising a symmetry axis extending from the center of the input face to the center of the output face; the first and second single multimode interference sections intersecting to form an L shaped compound multimode interference structure; the width of each single multimode interference section in a direction normal to Its symmetry axis being less than 15% of the length of the other single multimode interference section.

A device includes a scattering structure and a collection structure. The scattering structure is arranged to concurrently scatter incident electromagnetic radiation along a first scattering axis and along a second scattering axis. The first scattering axis and the second scattering axis are non-orthogonal. The collection structure includes a first input port aligned with the first scattering axis and a second input port aligned with the second scattering axis. A method includes scattering electromagnetic radiation along a first scattering axis to create first scattered electromagnetic radiation and along a second scattering axis to create second scattered electromagnetic radiation. The first scattering axis and the second scattering axis are non-orthogonal. The first scattered electromagnetic radiation is detected to yield first detected radiation and the second scattered electromagnetic radiation is detected to yield second detected radiation. The first detected radiation is phase aligned with the second detected radiation.

Example polarization splitter and rotator devices are described. In one example, an optical apparatus includes a splitter configured to split a light signal into a first signal having a first polarization and a second signal having a second polarization, a polarization rotator configured to rotate the second polarization of the second signal into a third polarization, and a polarization mode converter configured to convert the third polarization of the second signal into the first polarization. In certain aspects of the embodiments, the splitter can be a curved multi-mode inference (MMI) polarization splitter, and the polarization rotator comprises input and output ports, with the output port being wider than the input port. The polarization mode converter can be an asymmetrical waveguide taper mode converter. The devices described herein can overcome the deficiencies of conventional devices and provide low insertion loss, flat and/or wide wavelength response, high fabrication tolerance, and compact size.

A waveguide coupling structure includes: a first section that supports a mode that has an associated first intensity profile that substantially overlaps with an intensity profile associated with a mode supported by a first waveguide portion at a first end of the waveguide coupling structure; a second section that supports a mode that has an associated second intensity profile that substantially overlaps with an intensity profile associated with a mode supported by a second waveguide portion at a second end of the waveguide coupling structure; and a third section, between the first section and the second section, comprising a core structure on a bottom cladding and a supporting structure on the bottom cladding. The supporting structure: (1) overlaps with at least a portion of an intensity profile associated with a guided mode of the third section, and (2) has a shape that is asymmetric with respect to a propagation axis of the guided mode in a plane parallel to a surface of the bottom cladding.

Embodiments of the present disclosure are directed toward techniques and configurations for an optical accelerator including a photonics integrated circuit (PIC) for an optical neural network (ONN). In embodiments, an optical accelerator package includes the PIC and an electronics integrated circuit (EIC) that is heterogeneously integrated into the optical accelerator package to proximally provide pre- and post-processing of optical signal inputs and optical signal outputs provided to and received from an optical matrix multiplier of the PIC. In some embodiments, the EIC is a single EIC or discrete EICs to provide pre- and post-processing of the optical signal inputs and optical signal outputs including optical to electrical and electrical to optical transduction. Other embodiments may be described and/or claimed.

Embodiments of the present disclosure are directed toward techniques and configurations for optical couplers comprising a first optical waveguide and a second optical waveguide coupled to form a 22 optical unitary matrix to receive a respective first input optical signal and a second input optical signal. In embodiments the first optical waveguide and second optical waveguide form arms that converge alongside each other to direct the first input optical signal and the second input optical signal along a path that integrates a plurality of tunable phase shifters to transform the first input optical signal or the second input optical signal into a first output optical signal and second output optical signal to be output from the 22 optical unitary matrix. Additional embodiments may be described and claimed.

Systems and methods described herein are directed to polarization separation of incoming light signals associated with an imaging system, such as a Light Detection and Ranging (LIDAR) system. Example embodiments describe a system configured to direct incoming light signals to a polarization separator and capture the two polarization states of the incoming light signals. The system may process the two polarization states of the incoming light signals separately to extract information associated with reflecting objects within the field-of-view of the imaging system. The polarization separator may be a birefringent crystal positioned adjacent to an edge of a photonic integrated circuit (PIC) that is used for processing outgoing and incoming light signals associated with the imaging system. The PIC may include at least one on-chip polarization rotator for converting a light signal of one polarization state to a light signal of another polarization state.

An optical device includes a modulator and a tap coupler. The modulator includes an optical waveguide that is formed of a thin-film lithium niobate (LN) substrate and through which light passes, and an electrode that applies voltage to the optical waveguide, and modulates a phase of light that passes through the optical waveguide in accordance with an electric field in the optical waveguide, where the electric field corresponds to the voltage. The tap coupler includes at least a part formed of the thin-film LN substrate, and splits a part of the light that passes through an inside of the optical waveguide. The tap coupler includes a delayed interferometer that splits a part of the light that passes through the optical waveguide, at a split ratio corresponding to a phase difference of light that passes through an inside of the tap coupler from the optical waveguide.

The invention relates to an integrated polarisation splitter based on a sub-wavelength multimode interference coupler (110), in other words, a multimode interference coupler (110) with an anisotropic multimode waveguide region formed by a plurality of sections of core material (210) and a plurality of sections of a cladding material (230) alternately arranged in a periodic way, with a period () smaller than the wavelength of a light propagated through said anisotropic region. The core material sections (210) are rotated an angle () greater than zero with respect to a perpendicular with an input waveguide (120) to increase the anisotropic character of the multimode waveguide region.

In one example, an optoelectronic assembly may include a laser array, an amplifier array, and a multimode interference coupler optically coupling the laser array and the amplifier array. The laser array may include at least one primary laser and at least one spare laser configured to be activated if the primary laser fails. The amplifier array may include at least two amplifiers configured to amplify optical signals received from the laser array.