Ultra-responsive phase shifters for depletion mode silcon modulators
First Claim
1. A method of fabricating an optical modulator device, comprising:
- providing a wafer with a semiconductor layer thereon;
forming an optical waveguide in the semiconductor layer, the optical waveguide having a width W; and
,implanting N-type and P-type dopants into the optical waveguide in multiple implantation steps with an overlap to produce an N-type region at one side of the optical waveguide, a P-type region at another side of the optical waveguide, and wherein an injection window of n dopants and an injection window of p dopants have an implantation overlap region width D in the waveguide;
controlling an overlapping ratio D/W to produce a p-type region and an n-type region sharing a non-planar junction interface as viewed in a cross section taken perpendicular to a light propagation direction in said optical waveguide;
wherein the non-planar junction interface is configured to form at least two p/n junctions disposed with overlapping p-type and n-type regions in a direction normal to the wafer; and
annealing said implanted optical waveguide;
thereby forming within said optical waveguide a non-planar common junction configured to increase a junction area between said n-type region and said p-type region per unit length of said length dimension of said junction, so as to so as to enhance an overlap between an optical mode in said optical waveguide and said junction area when said optical modulator device is operational.
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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 0.3 V·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.
23 Citations
15 Claims
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1. A method of fabricating an optical modulator device, comprising:
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providing a wafer with a semiconductor layer thereon; forming an optical waveguide in the semiconductor layer, the optical waveguide having a width W; and
,implanting N-type and P-type dopants into the optical waveguide in multiple implantation steps with an overlap to produce an N-type region at one side of the optical waveguide, a P-type region at another side of the optical waveguide, and wherein an injection window of n dopants and an injection window of p dopants have an implantation overlap region width D in the waveguide; controlling an overlapping ratio D/W to produce a p-type region and an n-type region sharing a non-planar junction interface as viewed in a cross section taken perpendicular to a light propagation direction in said optical waveguide;
wherein the non-planar junction interface is configured to form at least two p/n junctions disposed with overlapping p-type and n-type regions in a direction normal to the wafer; andannealing said implanted optical waveguide; thereby forming within said optical waveguide a non-planar common junction configured to increase a junction area between said n-type region and said p-type region per unit length of said length dimension of said junction, so as to so as to enhance an overlap between an optical mode in said optical waveguide and said junction area when said optical modulator device is operational. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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Specification