Light emitting element and image display apparatus using the light emitting element

• US 8,866,172 B2
• Filed: 10/06/2010
• Issued: 10/21/2014
• Est. Priority Date: 10/22/2009
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Katayama, Ryuichi
• Primary Examiner(s): SAYADIAN, HRAYR
• Application Number:
  US13/503,212
• Publication Number:
  US 20120199855A1
• Time in Patent Office: 1,476 Days
• US Class Current: 257/98
• CPC Class Codes: H01L 33/405 Reflective materials
• CPC Class Codes: H01L 33/465 with a resonant cavity structure
• CPC Class Codes: H01L 33/58 Optical field-shaping elements

Abstract

The present invention is intended to realize a light emitting element which is easy to fabricate, is efficient, and is able to emit light in a uniform polarization state enabling the achievement of high luminance. A light emitting element of the present invention is a light emitting element including an active layer for generating light, the light emitting element including: a first reflection layer that allows the light generated at the active layer to reflect at a reflection section in which reflection members are periodically provided, and to exit from an exiting section between the reflection members; a polarization beam splitter layer that transmits a polarized light oriented in a first direction and diffracts a polarized light oriented in a second direction orthogonal to the first direction among the light exited from the exiting section; a wave plate layer that allows the light transmitted through the polarization beam splitter layer and the light diffracted at the polarization beam splitter layer to enter, and to exit as a light of a same polarization state; and a second reflection layer that reflects the light reflected at the first reflection light.

Claims

1. A light emitting element including an active layer for generating light, the light emitting element comprising:

a first reflection layer that allows the light generated at said active layer to reflect at a reflection section in which reflection members are periodically provided, and to exit from an exiting section between the reflection members;

a polarization beam splitter layer that transmits a polarized light oriented in a first direction and diffracts a polarized light oriented in a second direction orthogonal to the first direction among the light exited from said exiting section;

a wave plate layer that allows the light transmitted through said polarization beam splitter layer and the light diffracted at said polarization beam splitter layer to enter, and to exit as light having a same polarization state; and

a second reflection layer that reflects the light reflected at said first reflection layer.

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

said reflection section is adjacently disposed in a striped pattern.

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

said reflection section is adjacently disposed in a staggered pattern.

4. The light emitting element according to claim 1, wherein

within said wave plate layer, a portion that allows the light transmitted through said polarization beam splitter layer to enter, and a portion that allows the light diffracted at said polarization beam splitter layer to enter, allow an incident light to exit after respectively giving a different polarization rotation angle thereto.

5. The light emitting element according to claim 1, wherein

within said wave plate layer, a portion that allows the light transmitted through said polarization beam splitter layer to enter, and a portion that allows the light diffracted at said polarization beam splitter layer to enter, allow two orthogonal polarized components of an incident light to exit as a circularly polarized light after respectively giving a different phase difference thereto.

6. The light emitting element according to claim 1, wherein

letting P be a period of said reflection members, L1 be a distance between a center in thickness direction of the first reflection layer and a center in thickness direction of the second reflection layer, and L2 be a distance from a center in thickness direction of the active layer to the center of the first reflection layer,

P/(2L1+L2) is within from 0.9 to 6.5.

7. The light emitting element according to claim 6, wherein

P/(2L1+L2) is within from 1.2 to 4.5.

8. The light emitting element according to claim 6, wherein

P/(2L1+L2) is 2.3.

9. An image display apparatus using the light emitting element according to claim 1.