Two-dimensional photonic crystal surface emitting laser

• US 10,461,501 B2
• Filed: 08/28/2015
• Issued: 10/29/2019
• Est. Priority Date: 08/29/2014
• Status: Active Grant

• Current Assignee: Hamamatsu Photonics KK, Kyoto University, Mitsubishi Electric Corporation, ROHM Co., Ltd.
• Original Assignee: Kyoto University
• Inventors: Noda, Susumu, Kitagawa, Hitoshi, Liang, Yong, Watanabe, Akiyoshi, Hirose, Kazuyoshi
• Primary Examiner(s): Van Roy, Tod T
• Application Number:
  US15/505,560
• Publication Number:
  US 20170256911A1
• Time in Patent Office: 1,523 Days
• CPC Class Codes: H01S 5/04253 having specific optical properties, e.g. transparent electrodes
• CPC Class Codes: H01S 5/04254 characterised by the shape
• CPC Class Codes: H01S 5/0654 Single longitudinal mode emission
• CPC Class Codes: H01S 5/11 Comprising a photonic bandgap structure
• CPC Class Codes: H01S 5/18319 comprising a periodical structure in lateral directions
• CPC Class Codes: H01S 5/185 having only horizontal cavities, e.g. horizontal cavity surface-emitting lasers [HCSEL] comprising a photonic bandgap structure H01S5/11
• CPC Class Codes: H01S 5/34313 with a well layer having only As as V-compound, e.g. AlGaAs, InGaAs
• CPC Class Codes: H01S 5/34353 based on (AI)GaAs

Abstract

To provide a two-dimensional photonic crystal surface emitting laser capable of improving characteristics of light to be emitted, in particular, optical output power. The two-dimensional photonic crystal surface emitting laser 10X includes: a two-dimensional photonic crystal 123 including a plate-shaped base member 121 and modified refractive index regions 122 where the modified refractive index regions 122 have a refractive index different from that of the plate-shaped base member 121 and are two-dimensionally and periodically arranged in the base member; an active layer 11 provided on one side of the two-dimensional photonic crystal 123; and a first electrode 15A and a second electrode 16 provided sandwiching the two-dimensional photonic crystal 123 and the active layer 11 for supplying current to the active layer 11, where the second electrode 16 covers a region equal to or wider than the first electrode 15A, wherein the first electrode 15A is formed so as to supply the current to the active layer 11 with a different density depending on the in-plane position on the first electrode 15A.

Claims

1. A two-dimensional photonic crystal surface emitting laser, comprising:

a two-dimensional photonic crystal including a plate-shaped base member and modified refractive index regions where the modified refractive index regions have a refractive index different from that of the plate-shaped base member and are two-dimensionally and periodically arranged in the base member;

an active layer provided on one side of the two-dimensional photonic crystal; and

a first electrode and a second electrode provided sandwiching the two-dimensional photonic crystal and the active layer for supplying current to the active layer where the second electrode covers a range equal to or wider than the first electrode, wherein;

the first electrode is a mesh of conductive material, the mesh being composed of lines of the conductive material and inter-line regions as apertures each surrounded by the lines, and

the mesh is divided into a plurality of regions, each of the regions including at least one of the inter-line regions and having a mesh ratio that is different from the mesh ratio of the other regions, where each mesh ratio is defined by a ratio of an area of the lines in a unit mesh to a total area of the unit mesh, the unit mesh being composed of one of the inter-line regions and parts corresponding to a half width of the lines surrounding the one of the inter-line regions, each of the unit meshes being equally sized.

2. The two-dimensional photonic crystal surface emitting laser according to claim 1, wherein the first electrode is formed so as to supply the current to the active layer where the distribution has a highest density at a center of an in-plane position of the first electrode.

3. The two-dimensional photonic crystal surface emitting laser according to claim 1, wherein an interval between lines of the mesh is 1.4 times or less wider than current spreading in an in-plane direction of the active layer.

4. The two-dimensional photonic crystal surface emitting laser according to claim 1, wherein the mesh ratio in each of the regions decreases as a position is apart from a center of an in-plane position of the first electrode.

5. The two-dimensional photonic crystal surface emitting laser according to claim 4, wherein a region including the center in the first electrode consists only of the conductive material.

6. The two-dimensional photonic crystal surface emitting laser according to claim 1, wherein:

the first electrode is formed so as to supply the current to the active layer with a different density depending on an in-plane position on the first electrode to cause emission of light,

the light is amplified in the two-dimensional photonic crystal and causes laser oscillation, and

the two-dimensional photonic crystal surface emitting laser is configured to emit the oscillating laser light from the second electrode side.

7. A two-dimensional photonic crystal surface emitting laser, comprising:

a two-dimensional photonic crystal including a plate-shaped base member and modified refractive index regions where the modified refractive index regions have a refractive index different from that of the plate-shaped base member and are two-dimensionally and periodically arranged in the base member;

an active layer provided on one side of the two-dimensional photonic crystal; and

a first electrode and a second electrode provided sandwiching the two-dimensional photonic crystal and the active layer for supplying current to the active layer where the second electrode covers a range equal to or wider than the first electrode, wherein;

the first electrode is a mesh of conductive material, the mesh being composed of lines of the conductive material and inter-line regions as apertures each surrounded by the lines, and

a mesh ratio of the mesh changes continuously depending on a position, where the mesh ratio is defined by a ratio of an area of the lines in a unit mesh to a total area of the unit mesh, the unit mesh being composed of one of the inter-line regions and parts corresponding to a half width of the lines surrounding the one of the inter-line regions, each of the unit meshes being equally sized.

8. The two-dimensional photonic crystal surface emitting laser according to claim 7, wherein the mesh ratio decreases as a position is apart from a center of an in-plane position of the first electrode.

9. The two-dimensional photonic crystal surface emitting laser according to claim 7, wherein:

the first electrode is formed so as to supply the current to the active layer with a different density depending on an in-plane position on the first electrode to cause emission of light,

the light is amplified in the two-dimensional photonic crystal and causes laser oscillation, and

the two-dimensional photonic crystal surface emitting laser is configured to emit the oscillating laser light from the second electrode side.

10. A two-dimensional photonic crystal surface emitting laser, comprising:

a two-dimensional photonic crystal including a plate-shaped base member and modified refractive index regions where the modified refractive index regions have a refractive index different from that of the plate-shaped base member and are two-dimensionally and periodically arranged in the base member;

an active layer provided on one side of the two-dimensional photonic crystal; and

a first electrode and a second electrode provided sandwiching the two-dimensional photonic crystal and the active layer for supplying current to the active layer where the second electrode covers a range equal to or wider than the first electrode,

wherein the first electrode includes a circular conductor having a conductive material at a center of the circular conductor, ring-shaped conductors arranged concentric-circularly around the circular conductor, ring shaped insulators insulating the conductors, a ratio of a width of the ring shaped conductors to a width of the ring shaped insulators is higher in a center portion of the ring shaped conductors than in an outside portion of the ring shaped conductors, and a single linear conductor for electrically connecting the circular conductor and ring-shaped conductors.

11. The two-dimensional photonic crystal surface emitting laser according to claim 10, wherein:

the first electrode is formed so as to supply the current to the active layer with a different density depending on the in-plane position on the first electrode to cause emission of light,

the light is amplified in the two-dimensional photonic crystal and causes laser oscillation, and

the two-dimensional photonic crystal surface emitting laser is configured to emit the oscillating laser light from the second electrode side.