LIGHT EMITTING DEVICE

• US 20100322278A1
• Filed: 06/21/2010
• Published: 12/23/2010
• Est. Priority Date: 06/23/2009
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: MOCHIZUKI, Masamitsu
• Granted Patent: US 8,315,286 B2
• Time in Patent Office: Days
• US Class Current: 372/45.01
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: H01L 33/0045 the devices being superluminescent diodes
• CPC Class Codes: H01S 5/1007 Branched waveguides
• CPC Class Codes: H01S 5/1085 Oblique facets
• CPC Class Codes: H01S 5/3202 grown on specifically orientated substrates, or using orientation dependent growth
• CPC Class Codes: H01S 5/34326 with a well layer based on InGa(Al)P, e.g. red laser
• CPC Class Codes: H01S 5/5018 using two or more amplifiers or multiple passes through the same amplifier
• CPC Class Codes: H01S 5/5063 operating above threshold

Abstract

A light emitting device includes: a single crystal substrate having a plane tilted from a low-index plane and first and second cladding layers sandwiching an active layer, wherein the active layer includes first and second parallel side surfaces, part of the active layer constitutes first and second gain regions, a first side surface reflectance is higher than a second side surface reflectance, each of the first and second gain regions is disposed from a first side surface end surface to a second side surface end surface, the first gain region end surface partially overlaps the second gain region end surface so the end surfaces do not overlap each other in the first and second gain regions, a perpendicular of the first side surface is parallel to an off-direction of the substrate, and the first and second gain regions have equal lengths.

Claims

1. A light emitting device comprising:

a substrate formed of a single crystal having a zinc blende structure, and having a plane tilted at a predetermined angle from a low-index plane as a principal surface;

a first cladding layer formed above the principal surface;

an active layer formed above the first cladding layer; and

a second cladding layer formed above the active layer,

wherein the active layer includes a first side surface and a second side surface parallel to the first side surface,

at least part of the active layer constitutes a first gain region and a second gain region,

a reflectance of the first side surface is higher than a reflectance of the second side surface in a wavelength region of light generated in the first gain region and the second gain region,

each of the first gain region and the second gain region is disposed from an end surface on the first side surface to an end surface on the second side surface,

at least part of the end surface of the first gain region located on the first side surface and part of the end surface of the second gain region located on the first side surface overlap with each other,

the end surface on the first side surface and the end surface on the second side surface fail to overlap with each other in a plan view from the first side surface side in each of the first gain region and the second gain region,

a perpendicular of the first side surface is parallel to an off-direction of the substrate in a plan view, and

a length of the first gain region and a length of the second gain region are equal to each other.

2. The light emitting device according to claim 1, wherein

an amount of an angle of the first gain region with respect to the off-direction and an amount of angle of the second gain region with respect to the off-direction are equal to each other in a plan view.

3. The light emitting device according to claim 1, wherein

the first gain region has a reflection surface adapted to reflect light proceeding through the first gain region, and disposed between the first side surface and the second side surface, and

light emitted from the end surface of the first gain region located on the second side surface and light emitted from the end surface of the second gain region on the second side surface proceed toward the same direction.

4. The light emitting device according to claim 3, wherein

the reflection surface is disposed on a third side surface of the active layer perpendicular to the first side surface and the second side surface,

the first gain region has a first part disposed from the first side surface to the third side surface and a second part disposed from the third side surface to the second side surface, and

an angle of the first part with respect to the perpendicular of the first side surface, an angle of the second part with respect to the perpendicular of the first side surface, and an angle of the second gain region with respect to the perpendicular of the first side surface are the same in a plan view.

7. The light emitting device according to claim 1, further comprising:

a first electrode electrically connected to the first cladding layer; and

a second electrode electrically connected to the second cladding layer,

wherein the first electrode is contact with a first layer having ohmic contact with the first electrode,

the second electrode is contact with a second layer having ohmic contact with the second electrode, and

at least one of a contact surface between the first electrode and the first layer and a contact surface between the second electrode and the second layer has a planar shape the same as a planar shape of the first gain region and the second gain region.

8. The light emitting device according to claim 1, wherein

the first gain region and the second gain region form a pair of gain regions, and

a plurality of pairs of gain regions is disposed.

5. A light emitting device comprising:

a substrate formed of a single crystal having a zinc blende structure, and having a plane tilted at a predetermined angle from a low-index plane as a principal surface;

a first cladding layer formed above the principal surface;

an active layer formed above the first cladding layer; and

a second cladding layer formed above the active layer,

wherein the active layer includes a first side surface and a second side surface parallel to the first side surface,

at least part of the active layer constitutes a first gain region and a second gain region,

a reflectance of the first side surface is higher than a reflectance of the second side surface in a wavelength region of light generated in the first gain region and the second gain region,

each of the first gain region and the second gain region is disposed from an end surface on the first side surface to an end surface on the second side surface,

at least part of the end surface of the first gain region located on the first side surface and part of the end surface of the second gain region located on the first side surface overlap with each other,

the end surface on the first side surface and the end surface on the second side surface fail to overlap with each other in a plan view from the first side surface side in each of the first gain region and the second gain region,

a perpendicular of the first side surface is parallel to an off-direction of the substrate in a plan view, and

the second gain region includes

a first gain portion having a tilt amount equal to an amount of tilt of the first gain region with respect to the off-direction in a plan view, and

a second gain portion having a tilt amount different from the amount of tilt of the first gain region with respect to the off-direction in a plan view, and

a length of the first gain portion is larger than a length of the second gain portion.

6. The light emitting device according to claim 5, wherein

the first gain region has a linear shape in a plan view,

the second gain region includes a curved gain section, and

light emitted from the end surface of the first gain region located on the second side surface and light emitted from the end surface of the second gain region on the second side surface proceed toward the same or converging directions.