Optical modulator
First Claim
1. An optical modulator comprising:
- a substrate;
an optical waveguide disposed upon the substrate and characterized by a width dimension, a length dimension, and a height dimension, the height dimension being perpendicular to the substrate;
a p-type region of semiconductor material disposed within the optical waveguide;
an n-type region of semiconductor material disposed within the optical waveguide;
wherein the n-type region and the p-type region share a non-planar junction interface that is shaped so as to enhance an overlap between an optical mode in the optical waveguide and the junction interface when the optical modulator semiconductor device is operational; and
wherein at least one of the p-type region and the n-type region comprises a protrusion interposed in the height dimension between portions of the other of the p-type region and the n-type region;
wherein the p-type region comprises a plurality of p- type protrusions spaced along the length dimension, each of the p-type protrusions interposed in the height dimension between portions of the n-type region, and wherein the n-type region comprises a plurality of n-type protrusions interleaved with the p-type protrusions along the length dimension, each of the n-type protrusions interposed in the height dimension between portions of the p-type region.
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Accused Products
Abstract
A novel phase shifter design for carrier depletion based silicon modulators, based on an experimentally validated model, is described. It is believed that the heretofore neglected effect of incomplete ionization will have a significant impact on ultra-responsive phase shifters. A low VπL product of 0.3V·cm associated with a low propagation loss of 20 dB/cm is expected to be observed. The phase shifter is based on overlapping implantation steps, where the doses and energies are carefully chosen to utilize counter-doping to produce an S-shaped junction. This junction has a particularly attractive VπL figure of merit, while simultaneously achieving attractively low capacitance and optical loss. This improvement will enable significantly smaller Mach-Zehnder modulators to be constructed that nonetheless would have low drive voltages, with substantial decreases in insertion loss. The described fabrication process is of minimal complexity; in particular, no high-resolution lithographic step is required.
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Citations
15 Claims
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1. An optical modulator comprising:
- a substrate;
an optical waveguide disposed upon the substrate and characterized by a width dimension, a length dimension, and a height dimension, the height dimension being perpendicular to the substrate;
a p-type region of semiconductor material disposed within the optical waveguide;
an n-type region of semiconductor material disposed within the optical waveguide;
wherein the n-type region and the p-type region share a non-planar junction interface that is shaped so as to enhance an overlap between an optical mode in the optical waveguide and the junction interface when the optical modulator semiconductor device is operational; and
wherein at least one of the p-type region and the n-type region comprises a protrusion interposed in the height dimension between portions of the other of the p-type region and the n-type region;
wherein the p-type region comprises a plurality of p- type protrusions spaced along the length dimension, each of the p-type protrusions interposed in the height dimension between portions of the n-type region, and wherein the n-type region comprises a plurality of n-type protrusions interleaved with the p-type protrusions along the length dimension, each of the n-type protrusions interposed in the height dimension between portions of the p-type region. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
- a substrate;
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12. A method of fabricating an optical modulator comprising:
- a) providing a semiconductor material upon a planar substrate; and
, b) forming an optical waveguide with the semiconductor material, the optical waveguide comprising a p-type region and an n-type region defined therein so that at least one of the p-type region and the n-type region comprises a protrusion region interposed between portions of the other of the p-type region and the n-type region in a height dimension normal to the substrate, said protrusion region defining a non-planar junction interface between the n-type and p-type regions for enhancing an overlap between an optical mode of the optical waveguide and the non-planar junction interface;
wherein b) comprises defining a slab waveguide structure in the semiconductor material;
wherein b) includes implanting n-type and p-type dopants into the slab waveguide structure in multiple implantation steps to produce the n-type and p-type regions, respectively;
wherein b) comprises defining an implantation overlap region in the slab waveguide structure, and wherein the step of implanting comprises implanting the n-type dopants and the p-type dopants into the implantation overlap region at different energies so at to form a first dopant distribution within the implantation overlap region with two peaks in a direction normal to the substrate, and implanting the other of the n-type dopants and p-type dopants at a third energy so at to form a second dopant distribution in the implantation overlap region, the second dopant distribution having a peak that is located between the two peaks of the first dopant distribution in the direction normal to the substrate. - View Dependent Claims (13, 14, 15)
- a) providing a semiconductor material upon a planar substrate; and
Specification