A method includes etching a silicon layer to form a silicon slab and an upper silicon region over the silicon slab, and implanting the silicon slab and the upper silicon region to form a p-type region, an n-type region, and an intrinsic region between the p-type region and the n-type region. The method further includes etching the p-type region, the n-type region, and the intrinsic region to form a trench. The remaining portions of the upper silicon region form a Multi-Mode Interferometer (MMI) region. An epitaxy process is performed to grow a germanium region in the trench. Electrical connections are made to connect to the p-type region and the n-type region.

Structures for a wavelength-division multiplexing filter and methods of forming a structure for a wavelength-division multiplexing filter. The structure includes a first slab having a first perimeter, a first waveguide core coupled to the first slab, and a plurality of second waveguide cores coupled to the first slab. A second slab is positioned to overlap with the first slab. The second slab includes a second perimeter and openings that are distributed inside the second perimeter. The openings of the second slab penetrate through the second slab.

Structures for a wavelength-division multiplexing filter and methods of forming a structure for a wavelength-division multiplexing filter. The structure includes a first slab having a first perimeter, a first waveguide core coupled to the first slab, and a plurality of second waveguide cores coupled to the first slab. A second slab is positioned to overlap with the first slab. The second slab includes a second perimeter and openings that are distributed inside the second perimeter. The openings of the second slab penetrate through the second slab.

Disclosed is an all-fiber optical vortex laser based on resonance of orbital angular momentum modes. The all-fiber optical vortex laser has an annular cavity structure, and includes a narrow-linewidth pump laser, an optical amplifier, an orbital angular momentum mode generator, a first polarization controller, an optical fiber circulator, an optical fiber coupler, a second polarization controller and a vortex optical fiber. The orbital angular momentum mode generator (3) realizes directional conversion from a fundamental transverse mode in a single-mode optical fiber into an orbital angular momentum mode with a specific topological charge in a vortex optical fiber. The optical fiber coupler can realize directional coupling from an orbital angular momentum mode in one vortex optical fiber to an orbital angular momentum mode in another vortex optical fiber; the vortex optical fiber is an optical fiber supporting stable transmission of an orbital angular momentum model.

A method includes etching a silicon layer to form a silicon slab and an upper silicon region over the silicon slab, and implanting the silicon slab and the upper silicon region to form a p-type region, an n-type region, and an intrinsic region between the p-type region and the n-type region. The method further includes etching the p-type region, the n-type region, and the intrinsic region to form a trench. The remaining portions of the upper silicon region form a Multi-Mode Interferometer (MMI) region. An epitaxy process is performed to grow a germanium region in the trench. Electrical connections are made to connect to the p-type region and the n-type region.

The present disclosure relates to semiconductor structures and, more particularly, to non-planar waveguide structures and methods of manufacture. The structure includes: a first waveguide structure; and a non-planar waveguide structure spatially shifted from the first waveguide structure and separated from the first waveguide structure by an insulator material.

An optical delay between a first fiber and a second fiber is temperature compensated by combining fibers with different thermal path length changes. In some examples, fibers with different buffer coatings exhibit different path length changes per unit length and temperature. Combining such fibers in a fiber array provides a path length difference that is substantially independent of temperature.

The present disclosure relates to semiconductor structures and, more particularly, to non-planar waveguide structures and methods of manufacture. The structure includes: a first waveguide structure; and a non-planar waveguide structure spatially shifted from the first waveguide structure and separated from the first waveguide structure by an insulator material.

The present disclosure relates to semiconductor structures and, more particularly, to non-planar waveguide structures and methods of manufacture. The structure includes: a first waveguide structure; and a non-planar waveguide structure spatially shifted from the first waveguide structure and separated from the first waveguide structure by an insulator material.

For multi-mode interference (MMI) couplers that have a plurality of input and output ports, e.g. 44, a large number of modes may be supported in the multimode region, e.g. >10, as the width of the MMI core grows larger. In order for MMI couplers to form good images, the supported modes preferably have low modal phase error, which can't be achieved using a conventional single layer design. Accordingly, a multi-mode interference (MMI) coupler comprising an MMI core comprising a plurality of waveguide core strips alternating with a plurality of cladding strips solves the aforementioned problems.