Patent ID: 8873899

Claim:
An apparatus comprising: an optical waveguide structure configured to transmit a pair of optical signals in guided modes, the optical waveguide structure comprising a rotator, wherein the rotator is configured to: receive a first optical signal of the pair of optical signals polarized in a transverse electric (TE) mode and maintain the first optical signal in the TE mode as the first optical signal propagates through the rotator; and receive a second optical signal of the pair of optical signals polarized in a transverse magnetic (TM) mode and convert the TM mode optical signal to a TE mode optical signal as the second optical signal propagates through the rotator, wherein the rotator comprises a dual-layer core comprising a first layer disposed on a substrate and a second layer disposed on the first layer, wherein the first layer comprises a base portion that inversely tapers from a first end to a second end of the core, wherein a width of the base portion at the first end is less than the width of the base portion at the second end, and wherein the second layer comprises a rib portion, the rib portion having a width that is less than the width of the base portion at the first end and at the second end.