Integrated polarization splitter-rotator

A method, comprising:

• transmitting light into a rotator, the rotator including:
• an optical cladding including a top optical cladding and a bottom optical cladding;
• a silicon nitride (SiNx) waveguide core surrounded by the optical cladding and having an upper layer and a lower layer,
• wherein the upper layer has a first upper width and a second upper width, and the first upper width decreasingly tapers to the second upper width across a length of the SiNx waveguide core,
• wherein the lower layer has a first lower width and a second lower width, and the first lower width increasingly tapers to the second lower width across the length of the SiNx waveguide core, and
• wherein the second upper width is greater than or equal to the second lower width;
• transmitting the light, from the rotator, to a mode splitter connected to the rotator;
• and
• outputting the light, from the mode splitter, via a plurality of waveguides.

An optical assembly, comprising:

• a rotator configured to transmit light, the rotator including:
• an optical cladding including a top optical cladding and a bottom optical cladding, and
• a silicon nitride (SiNx) waveguide core surrounded by the optical cladding and having an upper layer and a lower layer,
• wherein the upper layer has a first upper width and a second upper width, and the first upper width decreasingly tapers to the second upper width across a length of the SiNx waveguide core,
• wherein the lower layer has a first lower width and a second lower width, and the first lower width increasingly tapers to the second lower width across the length of the SiNx waveguide core, and
• wherein the second upper width is greater than or equal to the second lower width;
• and
• a mode splitter configured to transmit the light, the mode splitter optically connected to the rotator,
• wherein the mode splitter is associated with a mode splitter segment having a first end and a second end, and wherein the mode splitter segment includes a first waveguide and a second waveguide, and
• wherein the first waveguide has a first width corresponding to the first end of the mode splitter segment and a second width corresponding to the second end of the mode splitter segment, the first width being greater than or equal to the second width.