Semiconductor laser

• US 5,661,743 A
• Filed: 08/02/1996
• Issued: 08/26/1997
• Est. Priority Date: 01/23/1996
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Nagai, Yutaka
• Primary Examiner(s): Davie, James W.
• Application Number:
  US08/691,303
• Time in Patent Office: 389 Days
• Field of Search: 372/46, 372/45, 372/44
• US Class Current: 372/46.01
• CPC Class Codes: H01S 5/221 containing aluminium
• CPC Class Codes: H01S 5/2226 semiconductors with a specific doping
• CPC Class Codes: H01S 5/2231 with inner confining structure only between the active layer and the upper electrode
• 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 5/32316 comprising only (Al)GaAs

Abstract

A semiconductor laser includes an n type GaAs semiconductor substrate, an n type AlGaAs cladding layer, an active layer producing light having a wavelength equal to or larger than 900 nm, a p type AlGaAs cladding layer, and an n type AlGaAs current blocking layer having a current concentrating structure. The n type AlGaAs current blocking layer comprises Al_x Ga_1-x As having an Al composition ratio x smaller than an Al composition ratio of the p type AlGaAs cladding layer, and is doped with Si to a concentration equal to or larger than 1×10¹⁹ cm^-3. Therefore, since more V_III -Si_Ga complexes C are produced in the AlGaAs current blocking layer than those produced when the current blocking layer is GaAs and absorption of light having a wavelength of 0.9˜1.2 μm is promoted, generation of higher-order modes is reliably suppressed and laser light having a fundamental mode is stably produced. Consequently, a semiconductor laser for exciting a fiber amplifier and excellent as a pumping light source of an optical fiber is realized.

Claims

1. A semiconductor laser including:

a n type GaAs semiconductor substrate;

an n type AlGaAs cladding layer;

an active layer producing light having a wavelength no shorter than 900 nm;

a p type AlGaAs cladding layer having an Al composition ratio; and

an n type AlGaAs current blocking layer having a current concentrating structure, the n type AlGaAs current blocking layer comprising Al_x Ga_1-x Al having an Al composition ratio x smaller than the Al composition ratio of the p type AlGaAs cladding layer, the current blocking layer being doped with Si in a concentration no smaller than 1×

10¹⁹ cm^-3, and the current concentrating structure being a ridge structure comprising the p type AlGaAs cladding layer and having a striped-shaped ridge structure, and the n type AlGaAs current blocking layer disposed on both sides of the ridge of the p-type AlGaAs cladding layer.

2. The semiconductor laser of claim 1 wherein the n type AlGaAs current blocking layer has an Al composition ratio x larger than 0 and no larger than 0.3.

3. A semiconductor laser including;

a n type GaAs semiconductor substrate;

an n type AlGaAs cladding layer;

an active layer producing light having shorter than 900 nm;

a p type AlGaAs cladding layer having an Al composition ratio; and

an n type AlGaAs current blocking layer having a current concentrating structure, the n type AlGaAs current blocking layer comprising Al_x Ga_1-x Al having an Al composition ratio x smaller than the Al composition ratio of the p type AlGaAs cladding layer, the current blocking layer being doped with Si in a concentration no smaller than 1×

10¹⁹ cm^-3, and the current concentrating structure being an SAS (self-aligned structure) structure comprising the n type AlGaAs current blocking layer having a central stripe groove, and the p type GaAs cladding layer disposed on the n type AlGaAs current blocking layer including the stripe groove.

4. The semiconductor laser of claim 3 wherein the n type AlGaAs current blocking layer has an Al composition ratio x larger than 0 and no larger than 0.3.