Semiconductor laser

• US 5,365,536 A
• Filed: 07/20/1993
• Issued: 11/15/1994
• Est. Priority Date: 07/20/1992
• Status: Expired due to Fees

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Seki, Akinori
• Primary Examiner(s): Epps, Georgia Y.
• Application Number:
  US08/093,754
• Time in Patent Office: 483 Days
• Field of Search: 372/45, 372/50, 372/43
• US Class Current: 372/45.01
• CPC Class Codes: H01S 5/026 Monolithically integrated components, e.g. waveguides, monitoring photo-detectors, drivers stabilisation of output H01S5/06
• CPC Class Codes: H01S 5/0261 Non-optical elements, e.g. laser driver components, heaters H01S5/0265 takes precedence
• CPC Class Codes: H01S 5/223 Buried stripe structure H01S5/227 takes precedence
• CPC Class Codes: H01S 5/4018 Lasers electrically in series
• CPC Class Codes: H01S 5/4043 with vertically stacked active layers

Abstract

A semiconductor laser for radiating a laser beam when current flows in the forward direction includes a first laser structure, a tunnel diode structure and a second laser structure in sequence, the forward direction of the first laser structure and the second laser structure being coincident with the forward direction of the semiconductor laser, the forward direction of the tunnel diode structure being opposite to the forward direction of the semiconductor laser.

Claims

1. A semiconductor laser for radiating a laser beam when current flows in a forward direction, said semiconductor laser comprising:

a semiconductor substrate;

a first laser structure formed on said semiconductor substrate and having a forward direction coincident with said forward direction of said semiconductor laser;

a tunnel diode structure formed on said first laser structure and having a forward direction that is opposite to said forward direction of said semiconductor laser, said tunnel diode structure including;

a first p-type junction layer, and

a second n-type junction layer formed on said

first p-type junction layer, and

a second laser structure formed on said tunnel diode structure and having a forward direction coincident with said forward direction of said semiconductor laser;

wherein said first and second junction layers are formed of a material selected from a group including GaAs, InGaAs and InP; and

wherein said first and second junction layers have an impurity concentration of at least 1×

10¹⁸ /cm³ and a layer thickness of no more than 50 nm.

2. The semiconductor laser as defined in claim 1, wherein at least one of said first and second junction layers is formed of InGaAs.

3. The semiconductor laser as defined in claim 2, wherein said InGaAs layer has an impurity concentration of 1×

10¹⁸ /cm³.

4. The semiconductor laser as defined in claim 1, wherein said first and second junction layers are formed of In_y Ga_1-y As, and the value of the component ratio y in said first junction layer gradually increases toward said second junction layer, and the value of the component ratio y in said second junction layer gradually increases toward said first junction layer.

5. The semiconductor laser as defined in claim 1, wherein:

said semiconductor substrate is n-type;

said first laser structure comprises;

i) a first n-type clad layer,

ii) a first active layer formed on said first n-type clad layer, and

iii) a first p-type clad layer formed on said first active layer, and

said second laser structure comprises;

i) a second n-type clad layer,

ii) a second active layer formed on said second n-type clad layer, and

iii) a second p-type clad layer formed on said second active layer.

6. The semiconductor laser as defined in claim 5, wherein said semiconductor substrate is formed of a material selected from a group including GaAs and InP.

7. The semiconductor laser as defined in claim 5, wherein said first and second active layers are formed of a material selected from a group including GaAs and InGaAsP.

8. A semiconductor laser for radiating a laser beam when current flows in a forward direction, comprising:

a p-type semiconductor substrate;

a first laser structure formed on said semiconductor substrate and having a forward direction coincident with said forward direction of said semiconductor laser, said first laser structure comprising;

i) a first p-type clad layer,

ii) a first active layer formed on said first p-type clad layer, and

iii) a first n-type clad layer formed on said first active layer,

a tunnel diode structure formed on said first laser structure and having a forward direction that is opposite to said forward direction of said semiconductor laser, said tunnel diode structure including;

a first n-type junction layer, and

a second p-type junction layer formed on said first n-type junction layer, and

a second laser structure formed on said tunnel diode structure and having a forward direction coincident with said forward direction of said semiconductor laser, said second laser structure comprising;

i) a second p-type clad layer,

ii) a second active layer formed on said second p-type clad layer, and

iii) a second n-type clad layer formed on said second active layer,

wherein said first and second junction layers are formed of a material selected from a group including GaAs, InGaAs and InP; and

wherein said first and second junction layers have an impurity concentration of at least 1×

10¹⁸ /cm³ and a layer thickness of no more than 50 nm.