Method and system for providing directional light sources with broad spectrum

• US 10,505,344 B1
• Filed: 10/25/2018
• Issued: 12/10/2019
• Est. Priority Date: 05/17/2010
• Status: Active Grant

• Current Assignee: Kyocera SLD Laser Incorporated (Kyocera Corporation)
• Original Assignee: Soraa Laser Diode, Inc. (Kyocera Corporation)
• Inventors: Raring, James W., Schmidt, Mathew C., Chang, Yu-Chia
• Primary Examiner(s): Nguyen, Tuan N
• Application Number:
  US16/170,592
• Time in Patent Office: 411 Days
• Field of Search: 372 4401
• 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: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01S 2301/02 ASE (amplified spontaneous emission), noise; Reduction thereof
• CPC Class Codes: H01S 5/0427 for applying modulation to the laser
• CPC Class Codes: H01S 5/06251 Amplitude modulation
• CPC Class Codes: H01S 5/0651 Mode control
• CPC Class Codes: H01S 5/0652 Coherence lowering or collapse, e.g. multimode emission by additional input or modulation
• CPC Class Codes: H01S 5/2031 characterized by special waveguide layers, e.g. asymmetric waveguide layers or defined bandgap discontinuities
• CPC Class Codes: H01S 5/22 having a ridge or stripe structure
• CPC Class Codes: H01S 5/32025 non-polar orientation
• CPC Class Codes: H01S 5/320275 semi-polar orientation
• CPC Class Codes: H01S 5/34 comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers H01S5/36 takes precedence
• CPC Class Codes: H01S 5/3407 characterised by special barrier layers
• CPC Class Codes: H01S 5/3414 by vacancy induced interdiffusion
• CPC Class Codes: H01S 5/34333 with a well layer based on Ga(In)N or Ga(In)P, e.g. blue laser
• CPC Class Codes: H01S 5/4043 with vertically stacked active layers
• CPC Class Codes: H01S 5/405 Two-dimensional arrays
• CPC Class Codes: H01S 5/4087 emitting more than one wavelength

Abstract

A system and method for providing laser diodes with broad spectrum is described. GaN-based laser diodes with broad or multi-peaked spectral output operating are obtained in various configurations by having a single laser diode device generating multiple-peak spectral outputs, operate in superluminescence mode, or by use of an RF source and/or a feedback signal. In some other embodiments, multi-peak outputs are achieved by having multiple laser devices output different lasers at different wavelengths.

Claims

1. An apparatus comprising optical device comprising:

a gallium and nitrogen containing surface including a first crystalline surface region which has a semi-polar orientation with a {20-21}, {30-31}, {20-2-1}, {30-3-1}, or {11-22} plane;

an active region including at least one quantum well, each of the quantum wells having a thickness of at least 1.5 nm and at least one barrier layers, each of the barrier layers having a thickness between about 2 nm and about 22 nm;

a first cavity member overlaying the active region, the first cavity member having a length of at least 100 um, a width of at least 0.5 um, a first end having a reflectivity, a second end having a reflectivity, the first cavity member being configured to emit a directional beam of light having a spectral width of at least 3 nm, the first cavity member being configured to emit radiation at a wavelength between about 430 nm to 540 nm, the spectral width being adapted to reduce speckle associated with the directional beam;

a first electrode and a second electrode coupled to the first cavity member, the first electrode and the second electrode being insulated from each other, the first electrode being electrically coupled to a driver signal, and the second electrode being electrically coupled to an RF source;

a second cavity member overlaying the active region; and

a lens coupled to the optical device.

2. The apparatus of claim 1 wherein spectral width is at about 4 nm to 8 nm;

and wherein the first end has a reflectivity of at least 85%, and the second end has a reflectivity of 1% or less.

3. The apparatus of claim 2, wherein the first end has a reflectivity of at least 90%.

4. The apparatus of claim 1 wherein the second end is characterized by a reflectivity of less than about 0.2%.

5. The apparatus of claim 1, wherein the first crystalline surface region has a nonpolar orientation.

6. The apparatus of claim 5, wherein the first crystalline surface region has an m-plane orientation.

7. The apparatus of claim 1, wherein the spectral width is from 1 nm to 10 nm.

8. The apparatus of claim 1 wherein the spectral width is from 1 nm to 20 nm.

9. The apparatus of claim 1, wherein the device is configured to operate as a superluminescent diode.

10. The apparatus of claim 1, wherein the cavity member is configured to emit radiation at a wavelength between about 430 nm to about 465 nm.

11. The apparatus of claim 1, wherein the cavity member is configured to emit radiation at a wavelength between about 500 nm to 540 nm.

12. The apparatus of claim 1, wherein the apparatus is operable as a light source in a display system comprising the lens.

13. An apparatus comprising:

an optical device comprising;

a gallium and nitrogen containing surface having a first crystalline surface region orientation with a {20-21}, {30-31}, {20-2-1}, {30-3-1}, or {11-22} plane;

an active region comprising at least one quantum well and at least one barrier layer;

a first cavity member overlaying the active region, the first cavity member having a length of at least 100 um, a width of at least 0.5 um, and being configured to emit laser light with a spectral width of at least 0.5 nm;

a first electrode and a second electrode coupled to the first cavity member, the first electrode and the second electrode being insulated from each other, the first electrode being electrically coupled to a driver signal;

an RF source electrically coupled to the second electrode for providing RF modulation, the RF modulation being configured to induce spectral broadening and increase the spectral width to at least 1.5 nm;

a second cavity member overlaying the active region; and

a lens coupled to the optical device.

14. The apparatus of claim 13 wherein the spectral width of laser after RF modulation is at least 3 nm.

15. The apparatus of claim 13 wherein the first crystalline surface region orientation comprises a semipolar plane such as {20-21}, {30-31}, {20-2-1}, {30-3-1}, or {11-22}.

16. The apparatus of claim 13 wherein the laser light is blue or green light.