Patent ID: 7260282

Claim:
An optical isolator, comprising: a first polarizer including first and second ports, the first polarizer coupled to receive a forward propagating wave at the first port and to output at the second port a polarized forward propagating wave having a first plane of polarization; a non-reciprocal rotator coupled to receive the polarized forward propagating wave from the second port of the first polarizer and to rotate the polarized forward propagating wave from the first plane of polarization by an angle to a second plane of polarization, the non-reciprocal rotator having: a substrate layer; a layer of manganese silicon, and germanium (MnSiGe) disposed on the substrate layer; a first doped layer disposed on the layer of manganese, silicon, and germanium; a heterostructure disposed on the layer of p-doped silicon-germanium; a second doped layer disposed on the heterostructure; and a reciprocal rotator coupled to the non-reciprocal rotator to receive the polarized forward propagating wave and to rotate the polarized forward propagating wave from the second plane of polarization back to the first plane of polarization, wherein the first polarizer, the non-reciprocal rotator, and the reciprocal rotator are monolithically integrated into a single semiconductor die.