Laser diode device having a substantially circular light output beam and a method of forming a tapered section in a semiconductor device to provide for a reproducible mode profile of the output beam

• US 6,052,397 A
• Filed: 12/05/1997
• Issued: 04/18/2000
• Est. Priority Date: 12/05/1997
• Status: Expired due to Fees

• Current Assignee: Viavi Solutions, Inc. (Lumentum Holdings Inc.)
• Original Assignee: SDL PLC (RWS Holdings Plc)
• Inventors: Verdiell, Jean-Marc, Jeon, Heonsu
• Primary Examiner(s): Davie, James W.
• Application Number:
  US08/985,820
• Time in Patent Office: 865 Days
• Field of Search: 372/45, 372/50, 372/46, 385/28, 385/43, 385/49
• US Class Current: 372/46.01
• CPC Class Codes: G02B 6/1228 Tapered waveguides, e.g. integrated spot-size transformers for coupling with fibres G02B6/305
• CPC Class Codes: H01S 5/10 Construction or shape of the optical resonator , e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region H01S5/20 takes precedence
• CPC Class Codes: H01S 5/1014 Tapered waveguide, e.g. spotsize converter H01S5/1064 takes precedence
• CPC Class Codes: H01S 5/164 with window regions comprising semiconductor material with a wider bandgap than the active layer
• CPC Class Codes: Y10S 438/942 Masking

Abstract

A device and method for fabricating a high power laser diode device with an output emission with a nearly circular mode profile for efficient coupling into an optical fiber. A vertical taper waveguide and a window tolerance region are formed in a base structure of the device employing successive etching steps. Further regowth completes the device structure. The resultant laser device has a vertical and lateral tapered waveguide that adiabatically transforms the highly elliptical mode profile in an active gain section of the device into a substantially circular mode profile in a passive waveguide section of the device.

Claims

1. A laser diode device with an integrated taper waveguide section, comprising:

a substrate;

a first cladding layer formed on the substrate;

a waveguide region formed on said first cladding layer;

said waveguide region comprising a first waveguide layer over which is grown a second waveguide layer and a thin etch-stop layer formed between first and second waveguide layers; and

a vertical taper formed in a portion of said second waveguide layer terminating at and exposing a portion of said etch-stop layer providing a window region of a length within which a cleave can be performed to form a facet upon further completion of the device.

2. The laser diode device of claim 1 wherein said first waveguide layer is a passive waveguide and second waveguide layer is an active waveguide, an active region formed in said active waveguide.

3. The laser diode device of claim 2 wherein said active region comprises a single active layer, a single quantum well layer, or a plurality of multiple quantum well layers.

4. The laser diode device of claim 2 wherein said active region comprises at least one active layer.

5. The laser diode device of claim 1 wherein a second cladding layer is formed on said waveguide region, said second cladding layer having a lateral taper in a region thereof substantially coincident with said second waveguide taper, the combination of said vertical and lateral tapers providing adiabatic transformation of a propagating mode in the device along an optical cavity such that laser emission emerging from said first waveguide layer at a cleaved facet formed through said window region has a substantially circular mode profile.

6. The laser diode device of claim 5 wherein said second waveguide taper is orthogonal to said second cladding layer taper.

7. The laser diode device of claim 5 wherein said second waveguide taper and said second cladding layer taper have their tapers monotonically diminishing in opposite directions along said optical cavity.

8. The laser diode device of claim 5 wherein said first and second waveguide layers are indium gallium arsenide phosphide (InGaAsP).

9. The laser diode device of claim 5 wherein said first and second cladding layers and said etch-stop layer are indium phosphide (InP).

10. The laser diode device of claim 1 wherein a length of said taper region is a range of approximately 50 μ

m to approximately 100 μ

m.

11. The laser diode device of claim 1 wherein a thickness of said first waveguide layer is approximately 20 μ

m to approximately 30 μ

m.

12. The laser diode device of claim 1 wherein a light transparent layer is formed on said waveguide region, said second waveguide taper and said tolerance window region, a grating formed in said light transparent layer in a portion thereof extending only over said waveguide region.

13. The laser diode device of claim 12 wherein a second cladding layer is formed on said light transparent layer, said second cladding layer having a taper in a region thereof substantially coincident with said second waveguide taper, the combination of said tapers providing expansion of a propagating mode in the device along an optical cavity such that laser emission emerging from said first waveguide layer at an output facet formed via a cleave through said tolerance window region has a substantially circular mode profile.

14. The laser diode device of claim 13 further comprising:

a rear facet coated with a high reflection coating; and

said output facet is coated with an anti-reflection coating.