Smooth waveguide structures and manufacturing methods
First Claim
Patent Images
1. An integrated optical structure comprising:
- a semiconductor-on-insulator substrate comprising a semiconductor device layer;
a wire waveguide formed in the semiconductor device layer, the wire waveguide having a top surface and sidewalls and comprising a tapered region decreasing in width towards a narrow end; and
a second waveguide disposed above or below the tapered region of the wire waveguide at the narrow end, the second waveguide made from a different material than the wire waveguide, and the second waveguide and wire waveguide together forming an optical mode converter,wherein the sidewalls, along a length of the wire waveguide in the tapered region, do not extend laterally beyond the top surface of the wire waveguide and substantially consist of sidewall portions coinciding with crystallographic planes of the wire waveguide, andwherein, along a portion of the tapered region of the wire waveguide that has a width of less than 0.5 μ
m, a return loss is less than −
40 dB/mm across an operating wavelength range.
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Accused Products
Abstract
In integrated optical structures (e.g., silicon-to-silicon-nitride mode converters) implemented in semiconductor-on-insulator substrates, wire waveguides whose sidewalls substantially consist of portions coinciding with crystallographic planes and do not extend laterally beyond the top surface of the wire waveguide may provide benefits in performance and/or manufacturing needs. Such wire waveguides may be manufactured, e.g., using a dry-etch of the semiconductor device layer down to the insulator layer to form a wire waveguide with exposed sidewalls, followed by a smoothing crystallographic wet etch.
4 Citations
13 Claims
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1. An integrated optical structure comprising:
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a semiconductor-on-insulator substrate comprising a semiconductor device layer; a wire waveguide formed in the semiconductor device layer, the wire waveguide having a top surface and sidewalls and comprising a tapered region decreasing in width towards a narrow end; and a second waveguide disposed above or below the tapered region of the wire waveguide at the narrow end, the second waveguide made from a different material than the wire waveguide, and the second waveguide and wire waveguide together forming an optical mode converter, wherein the sidewalls, along a length of the wire waveguide in the tapered region, do not extend laterally beyond the top surface of the wire waveguide and substantially consist of sidewall portions coinciding with crystallographic planes of the wire waveguide, and wherein, along a portion of the tapered region of the wire waveguide that has a width of less than 0.5 μ
m, a return loss is less than −
40 dB/mm across an operating wavelength range. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A photonic integrated circuit (PIC) comprising:
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an optical mode converter comprising a first waveguide made of a first material and tapered towards one end, and disposed above or below the first waveguide at the tapered end, a second waveguide made of a second material, a refractive index of the first material being greater than a refractive index of the second material, wherein the first waveguide is a wire waveguide having a top surface and sidewalls, and wherein the sidewalls, along at least a portion of a length of the wire waveguide at the tapered end, do not extend laterally beyond the top surface and substantially consist of sidewall portions coinciding with crystallographic planes of the wire waveguide. - View Dependent Claims (10, 11, 12, 13)
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Specification