The present disclosure relates to semiconductor structures and, more particularly, to multi-mode optical waveguide structures with isolated absorbers and methods of manufacture. The structure includes: a waveguide structure including tapered segments; and at least one isolated waveguide absorber adjacent to the waveguide structure along its length.

An optical coupler includes a first waveguide including a first multi-mode waveguide section having a cross-section characterized by a first height and a first width that is greater than the first height and a second waveguide including a second multi-mode waveguide section having a cross-section characterized by a second height and a second width that is greater than the second height. The first multi-mode waveguide section is positioned adjacent to the second multi-mode waveguide section at least partially above or below the second multi-mode waveguide so that light entering the first multi-mode waveguide section is coupled from the first multi-mode waveguide section to the second multi-mode waveguide section. Methods for coupling light between waveguides with the optical coupler and optical devices that include the optical coupler are also described.

An optical device comprises first, second and third elements fabricated on a common substrate. The first element comprises an active waveguide structure supporting a first optical mode, the second element, fabricated on a planarized top surface of the first element, comprises a passive waveguide structure supporting a second optical mode, and the third element, at least partly butt-coupled to the first element, comprises an intermediate waveguide structure, positioned such that a top surface of the intermediate structure underlies a bottom surface of the passive waveguide structure. If the first optical mode differs from the second optical mode by more than a predetermined amount, a tapered waveguide structure in at least one of the second and third elements facilitates efficient adiabatic transformation between the first optical mode and the second optical mode. Mutual alignments of the first, second and third elements are defined using lithographic alignment marks.

Example implementations described herein are directed to a system involving one or more photonic integrated circuits having multi-mode waveguides and connected to a printed optical board through the use of multi-mode waveguide connectors described herein. The printed optical board can include an embedded multi-mode waveguide bus to facilitate optical signal to and from the photonic integrated circuits. The system can also include a chiplet such as a photonic integrated circuit with a single mode waveguide configured to connect to an optical fiber cable.

The optical module according to the present invention includes a photoelectric converter and an optical receptacle. The optical receptacle includes a first optical surface, a second optical surface, a transmission and reflection part, a recess, and a third optical surface. The transmission and reflection part is secured to the inner surface of the recess at a position that does not coincide with the optical path of signal light. The transmission and reflection part transmits the signal light incident on the first optical surface toward the second optical surface. The transmission and reflection part reflects the received light incident on the second optical surface toward the third optical surface. When viewed along a direction normal to a substrate, the optical path in the recess is inclined relative to the optical path between the second optical surface and the recess.

A method includes defining a first waveguide in a first region of an optical device over a first dielectric layer over a silicon on insulator (SOI) substrate of the optical device and disposing a second dielectric layer on the first waveguide and the first dielectric layer of the optical device. The method also includes defining a second region on the second dielectric layer, the first dielectric layer, and the SOI substrate. The second region includes an integrated trench structure defined in the SOI substrate. The method further includes etching the second region to form an etched second region, disposing a third dielectric layer in the etched second region, and disposing a second waveguide on at least the third dielectric layer. The second waveguide is disposed to provide an optical coupling between the second waveguide and the first 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 (Λ) smaller than the wavelength of a light propagated through said anisotropic region. The core material sections (210) are rotated an angle (α) greater than zero with respect to a perpendicular with an input waveguide (120) to increase the anisotropic character of the multimode waveguide region.

Embodiments disclosed herein generally relate to optical coupling between a highly-confined waveguide region and a low confined waveguide region in an optical device. The low confined waveguide region includes a trench in a substrate of the optical device in order to provide additional dielectric layer thickness for insulation between the substrate of the optical device and waveguides for light signals having a low optical mode. The low confined waveguide region is coupled to the highly-confined waveguide region via a waveguide overlap and in some embodiments via an intermediary coupling waveguide.

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.

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.