Silicon-based Modulator with Optimized Longitudinal Doping Profiles

Patent metadata

Field	Value
Publication number	US-2020192131-A1
Application number	US-201916609239-A
Country	US
Kind code	A1
Filing date	Jan 25, 2019
Priority date	Jan 26, 2018
Publication date	Jun 18, 2020
Grant date	—

Abstract

A silicon modulator where the doping profile varies along the lateral and/or longitudinal position in the transition zones to achieve improved performance in terms of optical attenuation or contact access resistance or both. A modulator includes a core; a first transition zone that is a P-side region adjacent to the waveguide core, the first transition zone has a first longitudinal doping profile; and a second transition zone that is an N-side region adjacent to the core on an opposite side as the first transition region, the second transition zone has a second longitudinal doping profile; the first longitudinal doping profile has a variation of doping concentration along a longitudinal direction in the first transition region to mimic a first lateral doping profile, and the second longitudinal doping profile has a variation of doping concentration along a longitudinal direction in the second transition region to mimic a second lateral doping profile.

First claim

1 - 15 . (canceled)

16 . A silicon-based modulator comprising:
a waveguide core that is a PN junction region; a first transition zone that is a P-side region adjacent to the waveguide core, the first transition zone has a first longitudinal doping profile; and a second transition zone that is an N-side region adjacent to the waveguide core on an opposite side as the first transition region, the second transition zone has a second longitudinal doping profile; wherein at least one of the first longitudinal doping profile and the second longitudinal doping profile has a variation of doping concentration along a longitudinal direction.

17 . The silicon-based modulator of claim 16 , wherein the variation of doping concentration is formed by a plurality of areas of different doping concentrations in the longitudinal direction

18 . The silicon-based modulator of claim 16 , wherein the variation of doping concentration results in one of lower optical losses for a given access resistance and lower access resistance for a given optical loss.

19 . The silicon-based modulator of claim 16 , wherein the waveguide core has a p-type doping of p and the first electrical contact has a p-type doping of p++ such that the first transition zone has k (k≥2) divisions P 1 , P 2 , . . . P k , each division effectively uniformly doped at a concentration level p 1 , p 2 , . . . p k , respectively, such that p≤p 1 <p 2 . . . <p k ≤p++, and
wherein the waveguide core has an n-type doping of n and the second electrical contact has an n-type doping of n++ such that the second transition zone has k (k≥2) divisions N 1 , N 2 , . . . N k , each division effectively uniformly doped at a concentration level n 1 , n 2 , . . . n k , respectively, such that n≤n 1 <n 2 . . . <n k ≤n++.

20 . The silicon-based modulator of claim 16 , wherein the first longitudinal doping profile and the second longitudinal doping profile are different.

21 . The silicon-based modulator of claim 16 , wherein one or more of the first longitudinal doping profile and the second longitudinal doping profile are periodic in the longitudinal direction.

22 . The silicon-based modulator of claim 16 , wherein one or more of the first longitudinal doping profile and the second longitudinal doping profile are aperiodic in the longitudinal direction.

23 . The silicon-based modulator of claim 16 , wherein one or more of the first longitudinal doping profile and the second longitudinal doping profile have a doping concentration adjacent to the corresponding electrical contact region equal therewith.

24 . The silicon-based modulator of claim 16 , wherein one or more of the first longitudinal doping profile and the second longitudinal doping profile have a doping concentration adjacent to the waveguide core equal therewith.

25 . The silicon-based modulator of claim 16 , wherein the variation of doping concentration mimics a lateral doping profile with constant longitudinal profile that is determined based on lower optical losses for a given access resistance or based on lower access resistance for a given optical loss.

26 . A method comprising:
providing a silicon-based modulator that includes
a waveguide core that is a PN junction region;
a first transition zone that is a P-side region adjacent to the waveguide core, the first transition zone has a first longitudinal doping profile; and
a second transition zone that is an N-side region adjacent to the waveguide core on an opposite side as the first transition region, the second transition zone has a second longitudinal doping profile;
wherein at least one of the first longitudinal doping profile and the second longitudinal doping profile has a variation of doping concentration along a longitudinal direction.

27 . The method of claim 26 , wherein the variation of doping concentration is formed by a plurality of areas of different doping concentrations in the longitudinal direction.

28 . The method of claim 26 , wherein the waveguide core has a p-type doping of p and the first electrical contact has a p-type doping of p++ such that the first transition zone has k (k≥2) divisions P 1 , P 2 , . . . P k , each division effectively uniformly doped at a concentration level p 1 , p 2 , . . . p k , respectively, such that p≤p 1 <p 2 . . . <p k ≤p++, and
wherein the waveguide core has an n-type doping of n and the second electrical contact has an n-type doping of n++ such that the second transition zone has k (k≥2) divisions N 1 , N 2 , . . . N k , each division effectively uniformly doped at a concentration level n 1 , n 2 , . . . n k , respectively, such that n≤n 1 <n 2 . . . <n k ≤n++.

29 . The method of claim 26 , wherein the first longitudinal doping profile and the second longitudinal doping profile are different.

30 . The method of claim 26 , wherein one or more of the first longitudinal doping profile and the second longitudinal doping profile are periodic in the longitudinal direction.

31 . The method of claim 26 , wherein one or more of the first longitudinal doping profile and the second longitudinal doping profile are aperiodic in the longitudinal direction.

32 . The method of claim 26 , wherein one or more of the first longitudinal doping profile and the second longitudinal doping profile have a doping concentration adjacent to a corresponding electrical contact region equal therewith.

33 . The method of claim 26 , wherein one or more of the first longitudinal doping profile and the second longitudinal doping profile have a doping concentration adjacent to the waveguide core equal therewith.

34 . A silicon-based modulator with an optimized longitudinal profile formed by a process comprising the steps of:
determining an input profile for lateral doping in a transition region in the silicon-based modulator, the transition region between a waveguide core and an electrical contact region, the input profile for the transition region is uniformly doped in an optical propagation direction that is a longitudinal direction; defining a number of implantation steps and associated dopant concentrations; and at each position along a lateral direction, determining an output profile dopant in the longitudinal direction such that its average is equal a dopant concentration of the input profile at a same lateral position.

35 . The silicon-based modulator of claim 34 , wherein the input profile is determined based on lower optical losses for a given access resistance or for based on lower access resistance for a given optical loss.

Assignees

• Ciena Corp

Inventors

• Delisle-Simard Alexandre
• Painchaud Yves

Classifications

• G02F1/025 Primary

  in an optical waveguide structure (G02F1/017, {G02F1/2257} take precedence) · CPC title

• G02F1/0156

  using free carrier absorption · CPC title

• G02F2202/105

  single crystal Si · CPC title

• G02F2202/06

  dopant · CPC title