An optical system includes a silicon (Si) substrate, a buried oxide (BOX) layer formed on the substrate, a silicon nitride (SiN) layer formed above the BOX layer, and a SiN waveguide formed in the SiN layer. In some embodiments, the optical system may additionally include an interposer waveguide adiabatically coupled to the SiN waveguide to form a SiN-interposer adiabatic coupler that includes at least the tapered section of the SiN waveguide, the optical system further including at least one of: a cavity formed in the Si substrate at least beneath the SiN-interposer adiabatic coupler or an oxide overlay formed between a top of a SiN core of the SiN waveguide and a bottom of the interposer waveguide. Alternatively or additionally, the optical system may additionally include a multimode Si—SiN adiabatic coupler that includes a SiN taper of a SiN waveguide and a Si taper of a Si waveguide.

In order to solve the problem of making optical signals pass at a low loss and low polarization dependence, this optical circuit element is configured from rib-type optical waveguides, each of which is configured from a core region, including a planar slab and protruding ribs, and cladding regions that are provided in contact with the top and the bottom of the core region. A first optical waveguide that is provided in the optical circuit element is provided with a plurality of intersection points where the first optical waveguide intersects optical waveguides other than the first optical waveguide, said intersection points being disposed on one straight line. The core width of the first optical waveguide in a region between the intersection points is larger than the core width of the first optical waveguide in regions other than the region between the intersection points, the first optical waveguide regions having different core widths are connected by means of a taper optical waveguide wherein the core width monotonously changes, and the thickness of the slab of the first optical waveguide in the region having the large core width is larger than the thickness of the slab of the first optical waveguide in the regions other than the region having the large core width.

An optical demultiplexer/multiplexer, comprising: a multimode interference waveguide; at least one first coupling waveguide which meets the multimode interference waveguide at at least one first location and a plurality of second coupling waveguides which meet the multimode interference waveguide at a plurality of second locations which are spaced in a direction of transmission in relation to the at least one first location, with the at least one first coupling waveguide and the second coupling waveguides together with the multimode interference waveguide providing a first angled multimode interferometer which operates to demultiplex a first optical signal having optical channels of a plurality of wavelengths or multiplex optical signals of a plurality of wavelengths into a first optical signal having optical channels of the plurality of wavelengths; at least one third coupling waveguide which meets the multimode interference waveguide at at least one third location and a plurality of fourth coupling waveguides which meet the multimode interference waveguide at a plurality of fourth locations which are spaced in a direction of transmission in relation to the at least one third location, with the at least one third coupling waveguide and the plurality of fourth coupling waveguides together with the multimode interference waveguide providing a second angled multimode interferometer which operates to demultiplex a second optical signal having optical channels of a plurality of wavelengths or multiplex optical signals of a plurality of wavelengths into a second optical signal having optical channels of the plurality of wavelengths; whereby the demultiplexer/multiplexer provides for the demultiplexing/multiplexing of first and second optical signals having optical channels of a plurality of wavelengths. In a further embodiment the first coupling waveguide of an optical demultiplexer/multiplexer comprising

A laser including a grating configured to reduce lasing threshold for a selected vertically confined mode as compared to other vertically confined modes.

According to various embodiments, there is provided an optical device including: a waveguide configured to propagate an electromagnetic wave, the waveguide including a first grating and further including a second grating; a first further waveguide including a first further grating, the first further waveguide having a first width, wherein the first further grating is coupled to the first grating to form a first pair of coupled gratings, wherein a grating period of the first further grating is at least substantially equal to a grating period of the first grating; a second further waveguide including a second further grating, the second further waveguide having a second width, wherein the second further grating is coupled to the second grating to form a second pair of coupled gratings, wherein a grating period of the second further grating is at least substantially equal to a grating period of the second grating.

There is a manufacturing error even if an RGB coupler is appropriately designed, and thus a problem that it is difficult to achieve the function as designed with good yield arises. To solve this problem, an optical circuit with a first waveguide in which light in a zero-th order mode is guided and a second waveguide having a larger width than the first waveguide, in which light in a primary mode is guided in which the first and second waveguides at least include a first curved portion in a curve shape curved toward the first waveguide while maintaining a combination of waveguide widths satisfying mode conversion conditions is provided.

Systems and methods for an integrated photonics vertical coupler are provided herein. In certain embodiments, a device includes a first waveguide having a first photon and a second photon propagating therein, wherein the first photon and the second photon are propagating in orthogonal modes. Further, the device includes a second waveguide having a second coupling portion in close proximity with a first coupling portion of the first waveguide, wherein a physical relationship between the first waveguide and the second waveguide along the length of the second coupling portion causes an adiabatic transfer of the first photon and the second photon into distinct orthogonal modes of the second waveguide at different locations in the second coupling portion.

Example methods, devices, and systems for optical transmission are disclosed. An example method can comprise coupling a plurality of optical filters to a substrate. The method can comprise coupling a polymeric waveguide to the plurality of optical filters. The polymeric waveguide can be configured to guide a free space optical signal along the polymeric waveguide and communicate, via the plurality of optical filters, one or more components of the free optical space signal to an integrated chip.

An integrated mode converter and multiplexer (/demultiplexer) is disclosed, which combines a multimode interference coupler (100), at least one phase-shifter (200) and a symmetrical Y-junction (300). The dispersion of the multimode interference coupler (100) is engineered through subwavelength structures in order to achieve a very wide bandwidth. Several phase-shifter (200) topologies for further bandwidth enhancement are disclosed, as well as architectures for multiplexing a greater number of optical modes.

Aspects described herein include a mode multiplexer comprising a first optical waveguide extending between a first port and a second port. A first input mode of an optical signal entering the first port is propagated through the first optical waveguide to the second port. The mode multiplexer further comprises a second optical waveguide configured to evanescently couple with a coupling section of the first optical waveguide. A second input mode of the optical signal entering the first port is propagated through the second optical waveguide to a third port. The first optical waveguide further defines a filtering section between the coupling section and the second port, the filtering section configured to filter the second input mode.