Semiconductor light emitting device

• US 5,627,851 A
• Filed: 02/01/1996
• Issued: 05/06/1997
• Est. Priority Date: 02/10/1995
• Status: Expired due to Term

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Takahashi, Takashi
• Primary Examiner(s): Davie, James W.
• Application Number:
  US08/595,499
• Time in Patent Office: 460 Days
• Field of Search: 372/36, 372/108, 372/109, 372/43
• US Class Current: 372/44.01
• CPC Class Codes: H01S 5/0207 Substrates having a special shape
• CPC Class Codes: H01S 5/02251 using optical fibres
• CPC Class Codes: H01S 5/02326 Arrangements for relative positioning of laser diodes and optical components, e.g. grooves in the mount to fix optical fibres or lenses
• CPC Class Codes: H01S 5/0234 Up-side down mountings, e.g. Flip-chip, epi-side down mountings or junction down mountings

Abstract

A semiconductor light emitting device of an edge emitting type in the present invention has an active layer surface parallel to a reference plane and has a light emitting surface formed by etching until below the active layer surface in a direction perpendicular to the reference plane. An upper surface of a substrate in front of the light emitting surface is inclined in a direction separated from the active layer surface as this upper surface advances forward from the light emitting surface. An angle formed between the reference plane and the upper surface of the substrate in front of the light emitting surface is greater than a half beam angle at half-power points of a far-field emission pattern in a vertical direction. In this construction, no light component within the full beam angle at half-power points of the far-field emission pattern as a large part of light emitted from the light emitting surface is reflected on the upper surface of the substrate in front of the light emitting surface. Accordingly, the influences of light interference can be reduced and an inclination of emitted light with respect to an optical fiber can be reduced so that a reduction in optical coupling efficiency can be restrained.

Claims

1. A semiconductor light emitting device of an edge emitting type having an active layer surface parallel to a reference plane and having a light emitting surface formed by etching until below the active layer surface in a direction perpendicular to the reference plane;

the semiconductor light emitting device being constructed such that an upper surface of a substrate in front of the light emitting surface is inclined in a direction separated from the active layer surface as this upper surface advances forward from the light emitting surface; and

an angle formed between the reference plane and the upper surface of the substrate in front of the light emitting surface is greater than a half beam angle at half-power points of a far-field emission pattern in a vertical direction.

2. A semiconductor light emitting device of an edge emitting type having an active layer surface parallel to a reference plane and having a light emitting surface formed by etching until below the active layer surface in a direction perpendicular to the reference plane;

the semiconductor light emitting device being constructed such that an upper surface of a substrate in front of the light emitting surface is inclined in a direction separated from the active layer surface as this upper surface advances forward from the light emitting surface;

an angle formed between the reference plane and the upper surface of the substrate in front of the light emitting surface is greater than a half beam angle at half-power points of a far-field emission pattern in a vertical direction; and

the substrate below the light emitting surface is undercut-etched.

3. A semiconductor light emitting device of an edge emitting type having a light emitting surface formed by etching until below an active layer surface;

the semiconductor light emitting device being constructed such that an upper surface of a substrate in front of the light emitting surface is inclined in a direction separated from the active layer surface as this upper surface advances forward from the light emitting surface; and

an angle φ

formed between the upper surface of the substrate in front of the light emitting surface and a die bonding surface of the semiconductor light emitting device is provided by the following formula

space="preserve" listing-type="equation">φ

=arcsin (λ

/4nd)

where λ

is a light emitting wavelength of the semiconductor light emitting device,

n is a refractive index of a medium outside the semiconductor light emitting device, and

d is a distance of a perpendicular line drawn from an active layer position of the light emitting surface to the upper surface of the substrate in front of the light emitting surface.

4. A semiconductor light emitting device of an edge emitting type which has a light emitting surface and an etched side face formed by etching until below an active layer surface and is formed in a mesa shape;

the semiconductor light emitting device being constructed such that an upper surface of a substrate in front of the light emitting surface is inclined in a direction separated from the active layer surface as this upper surface advances forward from the light emitting surface; and

an angle φ

formed between the upper surface of the substrate in front of the light emitting surface and a mesa-etched bottom surface of the substrate is provided by the following formula

space="preserve" listing-type="equation">φ

=arcsin (λ

/4nd)

where λ

is a light emitting wavelength of the semiconductor light emitting device,

n is a refractive index of a medium outside the semiconductor light emitting device, and

d is a distance of a perpendicular line drawn from an active layer position of the light emitting surface to the upper surface of the substrate in front of the light emitting surface.

5. A semiconductor light emitting device of an edge emitting type having a light emitting surface formed by etching until below an active layer surface;

the semiconductor light emitting device being constructed such that a substrate thickness is increased as the substrate is separated from the light emitting surface; and

when a back surface of the substrate is arranged on a horizontal surface, an angle φ

formed between the upper surface of the substrate in front of the light emitting surface and this horizontal surface is provided by the following formula

space="preserve" listing-type="equation">φ

=arcsin (λ

/4nd)

where λ

is a light emitting wavelength of the semiconductor light emitting device,

n is a refractive index of a medium outside the semiconductor light emitting device, and

d is a distance of a perpendicular line drawn from an active layer position of the light emitting surface to the upper surface of the substrate in front of the light emitting surface.