Light source, and device
In accordance with the invention, a light source for display and/or illumination is provided, the light source comprising a heterostructure including semiconductor layers, the heterostructure forming a waveguide between a first end and a second end, the heterostructure comprising a plurality of layers and comprising an optically active zone formed by the plurality of layers, the optically active zone capable of emitting light guided by said waveguide, at least two different radiative transitions being excitable in the optically active an electrical current between a p-side electrode and an n-side electrode, transition energies of said at least two different radiative transitions corresponding to wavelengths in the visible part of the optical spectrum, the light source further comprising means for preventing reflections of light from the waveguide by at least one of said first and second end back into the waveguide, thereby causing the light source to comprise a superluminescent light emitting diode.
1. A light source of visible light for display and/or illumination, the light source comprising a heterostructure including semiconductor layers, the heterostructure forming a waveguide between a first end and a second end, the heterostructure comprising a plurality of layers and comprising an optically active zone formed by the plurality of layers, the optically active zone capable of emitting light guided by said waveguide, at least two different radiative transitions being excitable in the optically active zone by an electrical current between a p-side electrode and an n-side electrode, transition energies of said at least two different radiative transitions corresponding to wavelengths in the visible part of the optical spectrum, wherein the optically active zone comprises at least one optically active region with multiple radiative transitions, whereby at least two different radiative transitions include transitions between at least three different energy levels in a single material of said optically active region, the light source further comprising means for preventing reflections of light from the waveguide by at least one of said first and second end back into the waveguide, thereby causing the light source to comprise a superluminescent light emitting diode.
2. The light source according to claim 1 , wherein said means for preventing reflections include at least one of,
an antireflective coating
an end facet of said waveguide being at an oblique angle to a waveguide direction,
the waveguide comprising a taper, whereby the waveguide is broadened or narrowed towards at least one of said ends,
an absorber region including a structure absorbing light of at least one of said first and second wavelengths.
3. The light source according to claim 1 , wherein the waveguide is index guided.
4. The light source according to claim 1 , wherein the waveguide is gain guided.
5. The light source according to claim 1 , wherein the optically active zone includes a nitride semiconductor material that includes Gallium.
6. The light source according to claim 5 , wherein the nitride semiconductor material including Gallium is In x Ga 1-x N with 0≦x<1.
7. The light source according to claim 6 , wherein x is between 0.05 and 0.35.
8. The light source according to claim 1 , wherein the optically active zone includes Zinc Oxide semiconductor material.
9. The light source according to claim 1 , wherein the superluminescent light emitting diode is a semiconductor optical amplifier (SOA) operated to amplify spontaneously emitted light.
10. The light source according to claim 1 , wherein the waveguide is both, gain guided and index guided.
11. The light source according to claim 1 , wherein the optically active zone includes Al x Ga 1-x N semiconductor material with 0≦x<1.
12. The light source according to claim 1 , wherein the light source has a central emission wavelength of between 400 nm and 600 nm or between 400 nm and 560 nm.
13. The light source according to claim 1 , wherein the at least one optically active region being at least one well layer.
14. The light source according to claim 1 , wherein the at least one optically active region being at least one layer, being not a quantum well layer.
15. The light source according to claim 1 , further comprising a casing including at least one light redirector.
16. The light source according to claim 1 , further comprising a casing including at least one light shield.
17. The light source according to claim 1 , further comprising a conversion dye.
18. The light source according to claim 1 , further comprising a grip or a handle.
19. A display and/or illumination device the device comprising a light source, the light source comprising a heterostructure including semiconductor layers, the heterostructure forming a waveguide between a first end and a second end, the heterostructure comprising a plurality of layers and comprising an optically active zone formed by the plurality of layers, the optically active zone capable of emitting light guided by said waveguide, at least two different radiative transitions being excitable in the optically active an electrical current between a p-side electrode and an n-side electrode, transition energies of said at least two different radiative transitions corresponding to wavelengths in the visible part of the optical spectrum, the light source further comprising means for preventing reflections of light from the waveguide by at least one of said first and second end back into the waveguide, thereby causing the light source to be a superluminescent light emitting diode, wherein the optically active zone comprises at least one optically active region with multiple radiative transitions, whereby at least two different radiative transitions include transitions between at least three different energy levels in a single material of said optically active region.
20. The display and/or illumination device according to claim 19 , wherein the superluminescent light emitting diode is a semiconductor optical amplifier (SOA) operated to amplify spontaneously emitted light.
21. The display and/or illumination device according to claim 19 , wherein the light source comprises mounting means and a collimation optics.