Ultra low-loss CMOS compatible silicon waveguides
First Claim
1. A low loss silicon-on-insulator (SOI)-based optical waveguiding structure comprising a silicon substrate;
- an insulating layer disposed over the silicon substrate, the insulating layer having a first refractive index value;
a relatively thin silicon surface layer disposed over at least a portion of the insulating layer, the silicon exhibiting a refractive index value greater than the first refractive index value of the insulating layer; and
an optically transparent semiconductor waveguiding structure disposed over a portion of the relatively thin silicon surface layer, the optically transparent waveguiding structure having a refractive index value less than the refractive index value of silicon but greater than the first refractive index value of the insulating layer.
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Accused Products
Abstract
A low loss optical waveguiding structure for silicon-on-insulator (SOI)-based arrangements utilizes a tri-material configuration including a rib/strip waveguide formed of a material with a refractive index less than silicon, but greater than the refractive index of the underlying insulating material. In one arrangement, silicon nitirde may be used. The index mismatch between the silicon surface layer (the SOI layer) and the rib/strip waveguide results in a majority of the optical energy remaining within the SOI layer, thus reducing scattering losses from the rib/strip structure (while the rib/strip allows for guiding along a desired signal path to be followed). Further, since silicon nitirde is an amorphous material without a grain structure, this will also reduce scattering losses. Advantageously, the use of silicon nitride allows for conventional CMOS fabrication processes to be used in forming both passive and active devices.
38 Citations
14 Claims
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1. A low loss silicon-on-insulator (SOI)-based optical waveguiding structure comprising
a silicon substrate; -
an insulating layer disposed over the silicon substrate, the insulating layer having a first refractive index value;
a relatively thin silicon surface layer disposed over at least a portion of the insulating layer, the silicon exhibiting a refractive index value greater than the first refractive index value of the insulating layer; and
an optically transparent semiconductor waveguiding structure disposed over a portion of the relatively thin silicon surface layer, the optically transparent waveguiding structure having a refractive index value less than the refractive index value of silicon but greater than the first refractive index value of the insulating layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification