Semiconductor laser

• US 6,434,178 B1
• Filed: 05/20/1999
• Issued: 08/13/2002
• Est. Priority Date: 09/24/1997
• Status: Expired due to Fees

• Current Assignee: Nippon Sanso Corporation (Mitsubishi Chemical Group Corp.)
• Original Assignee: Nippon Sanso Corporation (Mitsubishi Chemical Group Corp.)
• Inventors: Ubukata, Akinori
• Primary Examiner(s): Ip, Paul
• Assistant Examiner(s): MENEFEE, JAMES A
• Application Number:
  US09/308,232
• Time in Patent Office: 1,181 Days
• Field of Search: 372/43, 372/45
• US Class Current: 372/45.011
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: H01S 5/2004 Confining in the direction perpendicular to the layer structure
• CPC Class Codes: H01S 5/2009 by using electron barrier layers
• CPC Class Codes: H01S 5/2059 by means of particular conductivity zones, e.g. obtained by particle bombardment or diffusion
• CPC Class Codes: H01S 5/3211 characterised by special cladding layers, e.g. details on band-discontinuities
• CPC Class Codes: H01S 5/34 comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers H01S5/36 takes precedence
• CPC Class Codes: H01S 5/3403 having a strained layer structure in which the strain performs a special function, e.g. general strain effects, strain versus polarisation
• CPC Class Codes: H01S 5/3409 special GRINSCH structures
• CPC Class Codes: H01S 5/3434 with a well layer comprising at least both As and P as V-compounds
• CPC Class Codes: H01S 5/34366 based on InGa(Al)AS

Abstract

A semiconductor laser which can emit at high output, for which the threshold current and efficiency have a low temperature dependence. In GaInAs/GaInAsP semiconductor lasers, the lower the holding temperature, the higher the slope efficiency. As the operation temperature rises, and the threshold current becomes larger, the loss coefficient increases. As a result, external quantum efficiency falls and output drops. Accordingly, in order to enable applications in broad technical fields, the semiconductor laser emits at high output, for which the threshold current and efficiency have a low temperature dependence. The semiconductor laser includes a compressively strained quantum well semiconductor laser employing GaInAs/GaInAsP, carrier blocking layers are provided in a p-type waveguide layer and n-type waveguide layer having a band gap which is larger than the band gap of a smallest band gap of the waveguide layers.

Claims

1. A semiconductor laser, comprising:

a compressively strained quantum well semiconductor laser including GaInAs/GaInAsP and including p-type and n-type waveguide layers, each of said p-type and n-type waveguide layers including plural waveguide layers each with a different band gap;

a first p-type carrier blocking layer provided in said p-type waveguide layer, wherein a value of a band gap of said first carrier blocking layer is larger than a smallest value of said different band gaps of said plural waveguide layers of said p-type waveguide layer; and

a second n-type carrier blocking layer provided in said n-type waveguide layer, wherein a value of a band gap of said second carrier blocking layer is larger than a smallest value of said different band gaps of said plural waveguide layers of said n-type waveguide layer,

wherein a difference between the band gap of each carrier blocking layer and the smallest value of the different band gaps of the respective waveguide layers is in the range of 85 meV-190 meV,

wherein an energy difference between a band gap of a first ground state of the quantum well layers and the band gap of each of the carrier blocking layers is in the range of 300 meV-500 meV, and

wherein a thickness of the carrier blocking layer is in the range of 5 nm-10 nm.

2. A semiconductor laser according to claim 1, wherein an emission wavelength of the semiconductor laser is 1.74 μ

m.

3. A semiconductor laser according to claim 1, wherein a thickness of each carrier blocking layer is in the range of 5 nm-10 nm.

4. A semiconductor laser according to claim 2, wherein a thickness of each carrier blocking layer is in the range of 5 nm-10 nm.