Semiconductor optical device

• US 5,737,474 A
• Filed: 10/13/1995
• Issued: 04/07/1998
• Est. Priority Date: 10/13/1994
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Sato, Hiroshi, Takahashi, Makoto, Aoki, Masahiro
• Primary Examiner(s): Ngo, John
• Application Number:
  US08/542,840
• Time in Patent Office: 907 Days
• Field of Search: 257/94, 257/96, 257/98, 372/45, 372/46, 372/50, 385/108, 385/129-132
• US Class Current: 385/131
• CPC Class Codes: G02B 2006/12097 Ridge, rib or the like
• CPC Class Codes: G02B 2006/12121 Laser
• CPC Class Codes: G02B 2006/12142 Modulator
• CPC Class Codes: G02B 2006/12176 Etching
• CPC Class Codes: G02B 2006/12195 Tapering
• CPC Class Codes: G02B 6/1228 Tapered waveguides, e.g. integrated spot-size transformers for coupling with fibres G02B6/305
• CPC Class Codes: G02F 1/025 in an optical waveguide structure G02F1/017, G02F1/2257 take precedence
• CPC Class Codes: G02F 1/2257 the optical waveguides being made of semiconducting material
• 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 5/1064 varying width along the optical axis
• CPC Class Codes: H01S 5/2231 with inner confining structure only between the active layer and the upper electrode
• CPC Class Codes: H01S 5/50 Amplifier structures not provided for in groups H01S5/02 - H01S5/30

Abstract

A semiconductor optical device is provided which includes a semiconductor substrate, a first core layer disposed on the substrate with a second core layer being interposed between the substrate and the first core layer. The second core layer has a lower refractive index than that of the first core layer. A ridge-shaped optical waveguide region is formed in a top surface of the first core layer. The width of the ridge-shaped optical waveguide is modulated along a direction which coincides with an optical axis of the semiconductor optical device. Further, the width of a bottom surface of the ridge-shaped optical waveguide is selected not to be greater than 4 μm over a whole length thereof.

Claims

1. A semiconductor optical device, comprising:

a semiconductor substrate;

a first core layer disposed on said substrate with a second core layer being interposed between said substrate and said first core layer, said second core layer having a lower refractive index than that of said first core layer; and

a ridge-shaped optical waveguide region formed in a top surface of said first core layer;

wherein width of said ridge-shaped optical waveguide region is changed along a direction coinciding with an optical axis of said semiconductor optical device and wherein width of a bottom surface of said ridge-shaped optical waveguide does not exceed 4 μ

m over a whole length thereof.

2. A semiconductor optical device according to claim 1,

wherein said second core layer is implemented in a superlattice structure formed of materials differing from each other in respect to composition thereof.

3. A semiconductor optical device according to claim 1,

wherein angles formed between a surface of said substrate and both side walls of said ridge-shaped optical waveguide region, respectively, are each smaller than 90°

inclusive.

4. A semiconductor optical device according to claim 1,

wherein each of side walls of said ridge-shaped optical waveguide region is defined by a (111) A crystal plane.

5. A semiconductor optical device according to claim 1,

wherein said ridge-shaped optical waveguide region is formed by processing a cladding layer of InP forming a part the waveguide region by using one aqueous solution selected from a group which consists of an aqueous solution of hydrobromic acid, a mixed aqueous solution of hydrobromic acid and phosphoric acid and a mixed aqueous solution of hydrobromic acid and acetic acid.

6. A semiconductor optical device according to claim 1,

wherein said ridge-shaped optical waveguide region is formed by processing a cladding layer of InP forming a part of the waveguide region by using one aqueous solution selected from a group which consists of an aqueous solution of hydrochloric acid, a mixed aqueous solution of hydrochloric acid and phosphoric acid, and a mixed aqueous solution of hydrochloric acid and acetic acid.

7. A semiconductor optical device according to claim 1,

wherein said ridge-shaped optical waveguide region is formed by processing a cladding layer of AlGaAs forming a part of the waveguide region by using an aqueous solution of hydrofluoric acid.

8. A semiconductor optical device according to claim 1,

wherein said ridge-shaped optical waveguide region is formed by processing a cladding layer of In₀.51 G₀.49 P forming a part of the waveguide region by using one aqueous solution selected from a group which consists of an aqueous solution of hydrochloric acid, a mixed aqueous solution of hydrochloric acid and phosphoric acid, and a mixed aqueous solution of hydrochloric acid and acetic acid.

9. A semiconductor optical device according to claim 1,

wherein said ridge-shaped optical waveguide region is formed by processing a cladding layer of InGaAlP forming a part of waveguide region by using an aqueous solution of hydrofluoric acid.

10. A semiconductor optical device according to claim 9,

wherein said second core layer is implemented in a superlattice structure formed of a combination of materials selected from a group which consists of combinations of InAsP and InP, InGaAsP and InP, InAlAs and InP, InGaAlAs and InP, GaAs and InGaP, GaAs and InAsP, GaAs and InGaAsP, and GaAs and AlGaAs.

11. A semiconductor optical device according to claim 1,

wherein width of said ridge-shaped optical waveguide region is narrowed at a light emission end thereof when compared with the width of the remaining portion of said ridge-shaped optical waveguide region.

12. A semiconductor optical device according to claim 1,

wherein said ridge-shaped optical waveguide region includes at least two electrodes for application of a current or a voltage;

and

wherein said electrodes are formed on a surface of said semiconductor optical device at a side where said ridge-shaped optical waveguide is formed.

16. A semiconductor optical device according to claim 1, 13, 14 or 15, wherein said semiconductor optical device is a semiconductor laser device.

17. A semiconductor optical device according to claim 1, 13, 14 or 15, wherein said semiconductor optical device is an optical amplifier.

18. A semiconductor optical device according to claim 1, 13, 14 or 15, wherein said semiconductor optical device is an optical modulator.

19. A semiconductor optical device according to claim 1, 13, 14 or 15, wherein said semiconductor optical device is an optical switch.

20. A semiconductor optical device according to claim 1, 13, 14 or 15, wherein said semiconductor optical device is a photodetector.

13. A semiconductor optical device comprising:

an optical active region and at least an output region for an incident light, wherein said output region for the incident light comprises;

a first core layer and a second core layer, said second core layer having a lower refractive index than that of said first core layer; and

a ridge-shaped optical waveguide region formed on said first core layer,

wherein width of said ridge-shaped optical waveguide region is changed along a direction coinciding with an optical axis of said semiconductor optical device.

14. A semiconductor optical device comprising:

an optical active region and at least an output region for an incident light, wherein said output region for the incident light comprises;

a first core layer and a second core layer, said second core layer having a lower refractive index than that of said first core layer, wherein said second core layer comprises a superlattice structure; and

a ridge-shaped optical waveguide region formed on said first core layer,

wherein width of said ridge-shaped optical waveguide region is changed along a direction coinciding with an optical axis of said semiconductor optical device.

15. A semiconductor optical device comprising:

an optical active region and at least an output region for an incident light, wherein said output region for the incident light comprises;

a first core layer and a second core layer, said second core layer having a lower refractive index than that of said first core layer; and

a ridge-shaped optical waveguide region formed on said first core layer,

wherein width of said ridge-shaped optical waveguide region is changed along a direction coinciding with an optical axis of said semiconductor optical device, and

wherein width of a bottom surface of said ridge-shaped optical waveguide is smaller than width of a top surface of said ridge-shaped optical waveguide.