Semiconductor laser device with multi-directional reflector arranged therein

• US 5,432,812 A
• Filed: 07/12/1993
• Issued: 07/11/1995
• Est. Priority Date: 10/31/1990
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Kurobe, Atsushi, Sadamasa, Tetsuo, Kawakyu, Yoshita, Kushibe, Mitsuhiro, Tezuka, Tsutomu
• Primary Examiner(s): Davie, James W.
• Application Number:
  US08/089,093
• Time in Patent Office: 729 Days
• Field of Search: 372/92, 372/96, 372/108, 372/99, 372/45, 372/46
• US Class Current: 372/99
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: H01S 2301/18 Semiconductor lasers with special structural design for influencing the near- or far-field
• CPC Class Codes: H01S 5/1042 Optical microcavities, e.g. cavity dimensions comparable to the wavelength
• CPC Class Codes: H01S 5/1071 Ring-lasers
• CPC Class Codes: H01S 5/1078 with means to control the spontaneous emission, e.g. reducing or reinjection
• CPC Class Codes: H01S 5/1082 with a special facet structure, e.g. structured, non planar, oblique
• CPC Class Codes: H01S 5/1228 DFB lasers with a complex coupled grating, e.g. gain or loss coupling
• CPC Class Codes: H01S 5/18305 with emission through the substrate, i.e. bottom emission
• CPC Class Codes: H01S 5/18308 having a special structure for lateral current or light confinement
• CPC Class Codes: H01S 5/18319 comprising a periodical structure in lateral directions
• CPC Class Codes: H01S 5/18327 Structure being part of a DBR H01S5/18391 takes precedence
• CPC Class Codes: H01S 5/1835 Non-circular mesa
• CPC Class Codes: H01S 5/18352 Mesa with inclined sidewall
• CPC Class Codes: H01S 5/18388 Lenses
• CPC Class Codes: H01S 5/2004 Confining in the direction perpendicular to the layer structure
• CPC Class Codes: H01S 5/2027 Reflecting region or layer, parallel to the active layer, e.g. to modify propagation of the mode in the laser or to influence transverse modes
• CPC Class Codes: H01S 5/2205 comprising special burying or current confinement layers
• CPC Class Codes: H01S 5/227 Buried mesa structure ; Striped active layer
• CPC Class Codes: H01S 5/2275 mesa created by etching
• CPC Class Codes: H01S 5/32308 emitting light at a wavelength less than 900 nm
• CPC Class Codes: H01S 5/34313 : with a well layer having only As as V-compound, e.g. AlGaAs, InGaAs
• CPC Class Codes: H01S 5/4056 : emitting light in more than one direction

Abstract

A microcavity semiconductor laser disclosed therein includes a double-heterostructure section including an intermediate active layer sandwiched between a first or lower cladding layer and a second or upper cladding layer above a semiconductive substrate. A first multi-layered reflector section is arranged between the substrate and the double-heterostructure section to have its reflectance which becomes maximum near the oscillation wavelength of the laser. The upper cladding layer is semi-spherically formed. A three-dimensional optical reflector covers the double-heterostructure section, for controlling spontaneous emission obtained in the double-heterostructure section along various directions, and for increasing the coupling ratio of spontaneous emission with a specific laser mode, thereby to decrease the threshold current.

Claims

1. A light-emitting device comprising:

a semiconductive substrate;

a first cladding layer and a second cladding layer arranged above the substrate;

a double-heterostructure section including an intermediate active layer sandwiched between the first or cladding layer and the second cladding layer;

first multi-layered reflector section arranged between said substrate and said double-heterostructure section, for having a reflectance which is maximum near an oscillation wavelength to be generated; and

optical reflector means arranged to cover said double-heterostructure section, for increasing spontaneous emission coupled with a specific oscillation mode, and for decreasing spontaneous emission to be coupled with other oscillation modes.

2. A device according to claim 1, wherein said optical reflector means comprises means for controlling spontaneous emission along a plurality of directions so as to increase a coupling ratio of the spontaneous emission with the oscillation mode.

3. A device according to claim 2, wherein said second cladding layer comprises a semiconductive layer which is partially projected, and wherein said optical reflector means comprises:

a second multi-layered reflector section covering the partially projected layer and having a reflectance which is maximum near the oscillation wavelength.

4. A device according to claim 3, wherein said second multi-layered reflector section includes first semiconductor layers and second semiconductor layers which are different in refractive index from each other and which are alternately stacked on one another.

5. A device according to claim 4, wherein said first and second semiconductor layers have uniform optical thickness of one of several multiplied values of quarter of the oscillation wavelength.

6. A device according to claim 4, wherein said first and second multi-layered reflector sections are made from semiconductive material which are opposite in conductivity to each other.

7. A device according to claim 1, wherein one of said first and second cladding layers has a surface configuration which changes periodically.

8. A device according to claim 1, wherein at least one of said first and second cladding layers has a plurality of grooves arranged periodically.

9. A device according to claim 1, wherein said optical reflector means comprises:

a second multi-layered reflector section arranged on said double-heterostructure section, and having a reflectance which is maximum near the oscillation wavelength of said laser device;

a third multi-layered reflector section surrounding said double-heterostructure section, and being greater in resistance than said second multi-layered reflector section; and

the stacking direction of said third multi-layered reflector section being transverse to that of said second multi-layered reflector section.

10. A device according to claim 9, wherein each of said first, second, and third multi-layered reflector sections includes two kinds of semiconductor crystal layers which are alternately stacked on one another.

11. A device according to claim 9, further comprising:

means for electrically separating said first and third multi-layered reflector sections from each other.

12. A device according to claim 3, wherein said optical reflector means comprises:

a second multi-layered reflector section covering the partially projected layer and having a reflectance which is maximum near the oscillation wavelength.

13. A device according to claim 3, wherein the partially projected semiconductor layer comprises:

a half-orb-shaped layer having a profile that looks like a half moon.

14. A device according to claim 3, wherein the partially projected semiconductor layer comprises:

a half-column-shaped layer.

15. A device according to claim 3, herein the partially projected semiconductor layer comprises:

a pyramid-shaped layer.

16. A device according to claim 3, wherein the partially projected semiconductor layer comprises:

a triangular prism-like layer.