Monlithically coupled waveguide and phototransistor

• US 7,471,855 B2
• Filed: 07/13/2005
• Issued: 12/30/2008
• Est. Priority Date: 07/13/2005
• Status: Active Grant

• Current Assignee: Alcatel-Lucent USA, Inc. (Nokia Corporation)
• Original Assignee: Alcatel-Lucent USA, Inc. (Nokia Corporation)
• Inventors: Houtsma, Vincent Etienne, Weimann, Nils Guenter, Chen, Young-Kai, Leven, Andreas Bertold
• Primary Examiner(s): Pak, Sung H
• Application Number:
  US11/180,122
• Publication Number:
  US 20070014508A1
• Time in Patent Office: 1,266 Days
• Field of Search: None
• US Class Current: 385/14
• CPC Class Codes: G02B 6/30 for use between fibre and thin-film device
• CPC Class Codes: G02B 6/4204 the coupling comprising intermediate optical elements, e.g. lenses, holograms encapsulated active devices H01S5/02208, H01L33/52

Abstract

An optical integrated circuit comprises a semiconductor body, a semiconductor optical waveguide located on the body, and a bipolar phototransistor located on and optically coupled to the waveguide. In a preferred embodiment, the base region of the transistor is configured to absorb radiation propagating in the waveguide, but the emitter and collector regions are both configured not to absorb the propagating radiation. In a further preferred embodiment, the waveguide is configured to guide the radiation along a propagation axis therein, and the transistor makes an elongated footprint along the waveguide, the footprint being elongated along the direction of the propagation axis. In another preferred embodiment, the footprint is at least three times longer along the propagation axis than along a direction perpendicular thereto.

Claims

1. Wherein said waveguide includes an elongated, relatively narrow portion and a wider, paddle-like portion optically coupled thereto, said phototransistor being disposed on said paddle-like portion.

2. Wherein said waveguide is configured to guide optical radiation along a propagation axis therein, and wherein said phototransistor comprises base, emitter and collector regions, said base region being configured to absorb said radiation and said collector and emitter regions being configured not to absorb said radiation.

3. The apparatus of claim 2, wherein said base region has a bandgap narrower than that of either said emitter or collector regions.

4. The apparatus of claim 3, wherein said base region comprises In, Ga and As.

5. The apparatus of claim 4, wherein said emitter and collector regions comprise In and P or In and As.

6. Wherein said waveguide is formed on a major surface of said body and said phototransistor includes a bottom layer in contact with said waveguide, and wherein said waveguide includes a pair of cladding layers, one of said cladding layers comprising a portion of said body along said surface and the other of said cladding layers comprising said bottom layer.

7. An optical integrated circuit comprising:

a semiconductor body,

a semiconductor optical waveguide located on said body, said waveguide being configured to carry optical radiation at particular center wavelength, and

a bipolar heterojunction phototransistor located on and optically coupled to said waveguide,

said phototransistor comprising base, emitter and collector regions, said base region being configured to absorb radiation at said wavelength and said emitter and collector regions both being configured not to absorb said radiation at said wavelength.

8. The circuit of claim 7, wherein said base region has a bandgap narrower than that of either said emitter or collector regions.

9. The circuit of 8, wherein said body comprises an In-based semiconductor, said base region comprises In, Ga and As, and said emitter and collector regions comprise In and P or In and As.

10. An optical integrated circuit comprising:

a semiconductor body,

a semiconductor optical waveguide located on said body, said waveguide being configured to carry optical radiation at particular center wavelength, and

a bipolar heterojunction phototransistor located and optically coupled to said waveguide,

said waveguide being configured to guide said radiation along a propagation axis therein, and said phototransistor making a footprint along said waveguide, said footprint being elongated along the direction of said axis, and said footprint being at least three times longer along said axis than along a direction perpendicular thereto.

11. The circuit of claim 10, wherein said footprint is at least ten times longer along said axis than along a direction perpendicular thereto.

12. An optical integrated circuit comprising:

a semiconductor body,

a semiconductor optical waveguide located on said body, said waveguide being configured to carry optical radiation at particular center wavelength, and said waveguide including an elongated, a relatively narrow portion and a wider, paddle-like portion optically coupled thereto, and

a bipolar heterojunction phototransistor located on and optically coupled to said paddle-like portion of said waveguide,

said waveguide being configured to guide said radiation along a propagation axis therein,

said waveguide being formed on a major surface of said body, said phototransistor including a bottom layer in contact with said waveguide, and said waveguide including a pair of cladding layers, one of said cladding layers comprising a portion of said body along said surface and the other of said cladding layers comprising said bottom layer,

said phototransistor making a footprint along said waveguide, said footprint being elongated along the direction of said axis, and said footprint being at least three times longer along said axis than along a direction perpendicular thereto, and

said phototransistor comprising base, emitter and collector regions, said base region being configured to absorb radiation at said wavelength and said emitter and collector regions both being configured not to absorb said radiation at said wavelength.

13. The circuit of claim 12, wherein said base region has a bandgap narrower than that of either said emitter or collector regions.

14. The circuit of 13, wherein said body comprises an In-based semiconductor, said base region comprises In, Ga and As, and said emitter and collector regions comprise In and P or In and As.