Light emitting element having structural bodies arrayed at a first pitch along a first direction and arrayed at a second pitch different from said first pitch along a second direction and projection display device provided with same

• US 9,028,070 B2
• Filed: 10/15/2010
• Issued: 05/12/2015
• Est. Priority Date: 10/23/2009
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Tomiyama, Mizuho, Katayama, Ryuichi
• Primary Examiner(s): Ton, Toan
• Assistant Examiner(s): CRUZ, MAGDA
• Application Number:
  US13/503,297
• Publication Number:
  US 20120224147A1
• Time in Patent Office: 1,670 Days
• Field of Search: 353/20, 257/98, 372/98, 372/103, 372/106, 362/606, 362/19, 359/619
• US Class Current: 353/20
• CPC Class Codes: G02B 1/005 made of photonic crystals or photonic band gap materials photonic band-gap structures or photonic lattices in integrated optics G02B6/1225; photonic band-gap structures or photonic lattices in optical fibres G02B6/02295
• CPC Class Codes: G02B 6/1225 comprising photonic band-gap structures or photonic lattices
• CPC Class Codes: G03B 21/2033 LED or laser light sources
• CPC Class Codes: G03B 21/2073 Polarisers in the lamp house peculiar to electronic spatial light modulators H04N9/3197
• CPC Class Codes: G03B 33/12 using beam-splitting or beam-combining systems, e.g. dichroic mirrors
• CPC Class Codes: H01L 2933/0083 Periodic patterns for optical field-shaping in or on the semiconductor body or semiconductor body package, e.g. photonic bandgap structures
• CPC Class Codes: H01L 33/18 within the light emitting region
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H04N 9/3167 for polarizing the light beam polarizing optical systems per se G02B27/28
• CPC Class Codes: H10K 50/868 Arrangements for polarized light emission H10K50/86 takes precedence

Abstract

Provided is a light-emitting element having high luminance and high directivity and emitting light in a controlled polarization state. The light-emitting element comprises substrate 3 and light emitting part 10 disposed on substrate 3 for emitting light in which light intensity of a polarization component in first direction x parallel to substrate 3 is higher than light intensities of polarization components in other directions. Light emitting part 10 includes active layer 12 for generating light and a plurality of structural bodies 14a disposed on a light-emitting side of light emitting part 10 with respect to active layer 12 and arrayed two-dimensionally along a surface substantially parallel to active layer 12. Each of structural bodies 14a has width w1 along first direction x and width w2 along second direction y perpendicular to first direction x, width w1 along first direction x and width w2 along second direction y being different from each other in a cross section parallel to active layer 12. Structural bodies 14a are arrayed periodically at first pitch p1 along first direction x and arrayed periodically at second pitch p2, which is different from first pitch p1, along second direction y.

Claims

1. A light-emitting element comprising a substrate and a light emitting part disposed on the substrate,

wherein said light emitting part includes a semiconductor layer comprising a plurality of layers including an active layer for generating light, said active layer configured to emit light in which light intensity of a polarization component in a first direction substantially parallel to said substrate is higher than light intensities of polarization components in other directions, and further includes a plurality of structural bodies disposed on a light-emitting side of said semiconductor layer and arrayed two-dimensionally along a surface substantially parallel to said active layer;

each of said structural bodies has a width along said first direction and a width along a second direction perpendicular to said first direction, the width along said first direction and the width along the second direction being different from each other in a cross section parallel to said active layer; and

said structural bodies are arrayed periodically at a first pitch along said first direction and arrayed periodically at a second pitch, which is different from said first pitch, along said second direction.

2. The light-emitting element according to claim 1, wherein a ratio of the width along said first direction to said first pitch is about 0.5, and a ratio of the width along said second direction to said second pitch is about 0.5.

3. The light-emitting element according to claim 1, wherein when a wavelength of the light emitted from said light emitting part in a vacuum is represented by λ

, said first pitch is represented by p1, and said second pitch is represented by p2, the ratio (p1/λ

) of the first pitch p1 to said wavelength λ and

the ratio (p2/λ

) of the second pitch p2 to said wavelength λ

satisfy the following relationship;

0.4<

(p1/λ

)<

0.8<

(p2/λ

)<

1.2.

4. The light-emitting element according to claim 1, wherein a principal surface of said semiconductor layer is a nonpolar surface or a semipolar surface.

5. The light-emitting element according to claim 1, wherein said light emitting part further includes a polarizer disposed on a light-emitting surface of said semiconductor layer assembly, said polarizer being configured to transmit a polarization component parallel to said first direction and to reflect said polarization components in other directions.

6. The light-emitting element according to claim 1, wherein each of said structural bodies is a protrusion formed on a light-emitting surface side of said semiconductor layer.

7. The light-emitting element according to claim 1, wherein each of said structural bodies is a recess formed on a light-emitting surface side of said semiconductor layer.

8. The light-emitting element according to claim 1, wherein said semiconductor layer includes a group-III nitride.

9. The projection display apparatus comprising a light source including a light-emitting element according to claim 1, a light modulation element for modulating light emitted from said light source depending on an image signal, and a projection optical system for projecting the light modulated by said light modulation element.