Patent ID: 7065265

Claim:
A magnetic-semiconductor composite optical isolator comprising: a semiconductor waveguide that includes: a guide layer having one or more layers with a first end, a second end, a top, and a bottom, the guide layer operable to allow high wave incident the first end of the guide layer to propagate from the first end of the guide layer to the second end of the guide layer, which defines a positive propagation direction, and operable to allow a light wave incident the second end of the guide layer to propagate from the second end of the guide layer to the first end of the guide layer, which defines a negative propagation direction, a first clad layer provided relative the bottom of the guide layer, and a second clad layer provided relative the top of the guide layer, wherein the second clad layer has a thickness operable to allow an optical field penetration through the second clad layer by a light wave that propagates in the positive propagation direction of the guide layer, and operable to allow an optical field penetration through the second clad layer by a light wave that propagates in the negative propagation direction of the guide layer; and a magnetic-semiconductor composite layer provided in the presence of a magnetic field with at least a component of the magnetic field oriented in a direction perpendicular to the positive propagation direction of the guide layer and parallel to the magnetic vector of the optical field, the magnetic-semiconductor composite layer positioned relative the second clad layer of the waveguide to receive the optical field penetration through the second clad layer, the magnetic-semiconductor composite layer having a thickness and an index of refraction to attenuate a light wave that propagates in the portion of the guide layer in the negative propagation direction by an amount greater than the attenuation of a light wave that propagates in the portion of the guide layer in the positive propagation direction, wherein the magnetic-semiconductor composite layer includes magnetic particles positioned within a semiconductor layer.