VCSEL with monolithically integrated photodetector

• US 6,717,972 B2
• Filed: 08/02/2002
• Issued: 04/06/2004
• Est. Priority Date: 02/02/2000
• Status: Expired due to Term

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Steinle, Gunther, Wolf, Hans-Dietrich
• Primary Examiner(s): Ip, Paul
• Assistant Examiner(s): VY, HUNG T
• Application Number:
  US10/211,102
• Publication Number:
  US 20030021322A1
• Time in Patent Office: 613 Days
• Field of Search: 372/96, 372/45, 372/50
• US Class Current: 372/50.21
• CPC Class Codes: H01S 5/0264 for monitoring the laser-output
• CPC Class Codes: H01S 5/0427 for applying modulation to the laser
• CPC Class Codes: H01S 5/183 having only vertical cavities, e.g. vertical cavity surface-emitting lasers [VCSEL]
• CPC Class Codes: H01S 5/18358 containing spacer layers to adjust the phase of the light wave in the cavity
• CPC Class Codes: H01S 5/3095 Tunnel junction

Abstract

A VCSEL has an active layer, a photodetector in one of the DBR gratings and with a radiation-absorbing layer that is arranged in an antinode of a laser mode. The laser and the photodetector are electrically driven by a common contact on a thick, heavily doped spacer layer that ensures low laser impedance and little electrical crosstalk between the laser and the photodetector.

Claims

1. An optoelectronic component serving as a VCSEL, comprising:

DBR gratings serving as reflectors;

an active layer disposed between two of said DBR gratings and intended for generating radiation, the radiation having a laser mode with an antinode;

a photodetector located within one of said DBR gratings and provided with an intrinsically conductive region, a radiation-absorbing layer disposed within said intrinsically conductive region, with said radiation-absorbing layer being configured to overlap the antinode of the laser mode of the radiation; and

a thick and heavily doped spacer layer located between said active layer and said radiation-absorbing layer adjacent said intrinsically conductive region of said photodetector, said spacer layer being provided with a contact.

2. The component according to claim 1, wherein:

said laser mode has a photon energy; and

said radiation-absorbing layer has an energy band edge that is slightly lower than said photon energy of said laser mode.

3. The component according to claim 1, wherein:

said photodetector and said spacer layer have a nonresonant optical thickness with respect to said laser mode so that an electric field distribution of the radiation inside said DBR gratings remains unmodified.

4. The component according to claim 1, wherein:

said laser mode has a photon energy; and

said spacer layer has an energy band edge that is slightly higher than said photon energy of said laser mode.

5. The component according to claim 1, comprising:

at least one semiconductor layer adjoining said radiation-absorbing layer and being heavily doped to be n-type conductive;

said spacer layer being heavily doped to be n-type conductive.

6. The component according to claim 5, comprising:

a region adjacent said radiation-absorbing layer; and

at least one semiconductor layer adjoining said radiation-absorbing layer and having a grading in an energy band gap so that in said region adjacent said radiation-absorbing layer, the energy band gap grows toward said spacer layer.

7. The component according to claim 6, comprising:

a depletion layer; and

a device for applying an electrical voltage to modify an absorption in said radiation-absorbing layer;

said radiation-absorbing layer lying inside said depletion layer.

8. The component according to claim 6, comprising:

a depletion layer having an n-doped edge region; and

a structural device for applying an electrical voltage to modify an absorption in said radiation-absorbing layer;

said radiation-absorbing layer lying close to said n-doped edge region of said depletion layer.

9. The component according to claim 5, comprising:

a depletion layer; and

a device for applying an electrical voltage to modify an absorption in said radiation-absorbing layer;

said radiation-absorbing layer lying inside said depletion layer.

10. The component according to claim 5, comprising:

a depletion layer having an n-doped edge region; and

a structural device for applying an electrical voltage to modify an absorption in said radiation-absorbing layer;

said radiation-absorbing layer lying close to said n-doped edge region of said depletion layer.

11. The component according to claim 1, wherein:

said photodetector is a pin photodiode.

12. The component according to claim 1, wherein:

said photodetector is selected from a group consisting of a bipolar phototransistor and a heterobipolar phototransistor.

13. The component according to claim 1, wherein:

said photodetector includes two photodiodes that have a common anode.

14. The component according to claim 1, wherein:

said photodetector includes two photodiodes that have a common cathode.

15. The component according to claim 1, wherein:

said photodetector includes two photodiodes that have a common tunnel contact.