Polarization splitter rotator

A receiver, comprising:

• a PSR comprising:
• a rotator comprising a first layer comprising a first waveguide formed from a lower refractive index material and a second layer comprising a second waveguide formed from a higher refractive index material, wherein the rotator is configured to receive an optical signal comprising multiple modes at an input of the first waveguide, and, at an end of the rotator, the optical signal is primarily confined in the first waveguide and includes only one optical mode, wherein a width of the second waveguide increases at an input of the rotator and decreases at the end of the rotator, wherein the width of the second waveguide does not exceed 550 nm along a length of the rotator, and the width of the first waveguide ranges from 1 to 3 microns along the length of the rotator;
• and
• a splitter coupled to the first waveguide of the rotator,
• a third waveguide coupled to a first end of the splitter;
• and
• a fourth waveguide coupled to a second end of the splitter, wherein the first waveguide, third waveguide, and fourth waveguide are formed from a same material.

A receiver, comprising:

• a polarization beam splitter (PBS) configured to receive an optical signal comprising a first mode and a second mode;
• a third waveguide coupled to a first end of the PBS to receive light in the first mode;
• a polarization splitter rotator (PSR) comprising:
• a rotator comprising a first layer comprising a first waveguide formed from a lower refractive index material and a second layer comprising a second waveguide formed from a higher refractive index material, wherein the rotator is coupled to the PBS to receive light in the second mode at an input of the first waveguide, and, at an end of the rotator, the light is primarily confined in the first waveguide and has been rotated into the first mode, wherein a width of the second waveguide increases at an input of the rotator and decreases at the end of the rotator, wherein the width of the second waveguide does not exceed 550 nm along a length of the rotator, and the width of the first waveguide ranges from 1 to 3 microns along the length of the rotator;
• and
• a splitter coupled to the first waveguide of the rotator.