Dual-slab-layer low-loss silicon optical modulator
AssigneeInphi Corporation
InventorsXiaoguang Tu, Masaki Kato
Life of this patent
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Abstract
A silicon optical modulator is fabricated to have a multi-slab structure between the contacts and the waveguide, imparting desirable performance attributes. A first slab comprises dopant of a first level. A second slab adjacent to (e.g., on top of) the first slab, comprises a doped region proximate to a contact, and an intrinsic region proximate to the waveguide. The parallel resistance properties and low overlap between the highly doped silicon and optical mode pigtail afforded by the multi-slab configuration, allow the modulator to operate with reduced optical losses and at a high speed. Embodiments may be implemented in a Mach-Zehnder interferometer or in micro-ring resonator modulator configuration.
Claims20
An optical modulator comprising:
- a waveguide having a first waveguide portion of a first conductivity type and a second waveguide portion of a second conductivity type opposite to the first conductivity type, the waveguide configured to communicate an optical signal along a first axis defined within a silicon substrate;
- a first contact of the first conductivity type proximate to the first waveguide portion;
- a second contact of the second conductivity type proximate to the second waveguide portion;
- a first multi-slab structure offering parallel conductive pathways of different resistance between the first contact and the first portion;
- and
- a second multi-slab structure offering parallel conductive pathways of different resistance between the second contact and the second portion, wherein:
- a first slab of the first multi-slab structure proximate to the silicon substrate, is adjacent to a second slab of the first multi-slab structure distal from the silicon substrate, along a second axis orthogonal to the first axis.
A method comprising:
- creating a first conductive pathway of a first resistance between a first contact of a first conductivity type and a first waveguide portion of the first conductivity type;
- creating a second conductive pathway of a second resistance lower than the first resistance, between the first contact and the first waveguide portion, the second conductive pathway parallel to the first conductive pathway;
- creating a third conductive pathway of a third first resistance between a second contact of a second conductivity type opposite to the first conductivity type, and a second waveguide portion of the second conductivity type;
- creating a fourth conductive pathway of a fourth resistance lower than the third resistance, between the second contact and the second waveguide portion, the fourth conductive pathway parallel to the third conductive pathway;
- and
- applying a potential difference between the first contact and the second contact to reverse-bias a junction formed at an interface of the first waveguide portion and the second waveguide portion.
An optical modulator integrated with a silicon photonics system comprising:
- a first phase-shifter on a silicon substrate;
- a second phase-shifter on the silicon substrate;
- a first 2×2 splitter having a first exit port coupled to an input port of the first phase-shifter and a second exit port coupled to an input port of the second phase-shifter;
- and
- a second 2×2 splitter having a first entry port coupled to an output port of the first phase-shifter and a second entry port coupled to an output port of the second phase-shifter,
- wherein the first phase-shifter comprises,
- a first contact of the first conductivity type proximate to the first waveguide portion;
- a second contact of the second conductivity type proximate to the second waveguide portion;
- a first multi-slab structure offering parallel conductive pathways of different resistance between the first contact and the first portion;
- and
- a second multi-slab structure offering parallel conductive pathways of different resistance between the second contact and the second portion, wherein:
- a first slab of the first multi-slab structure proximate to the silicon substrate, is adjacent to a second slab of the first multi-slab structure distal from the silicon substrate, along a second axis orthogonal to the first axis.
Dependencies are inferred from the claim text.