Multi-electrode light emitting device
View Patent ↗The invention relates to a broad-band light emitting diode having an active layer composed of a plurality of light emission regions of differing materials for emitting light at a plurality of wavelengths, wherein each of the emission regions of the active layer is electrically controlled by a separate electrode for providing a broad-band emission or optical gain with a multi-point control of its spectral profile.
1. A light emitting diode (LED), comprising:
a semiconductor heterostructure;
a waveguide formed in said semiconductor heterostructure and having an output facet;
a plurality of light emission regions of said semiconductor heterostructure disposed along the waveguide for emitting light thereinto, wherein each light emission region has a material composition for emitting light that is spectrally centered at a different light emission wavelength than other light emission regions; and,
a plurality of electrical contacts for electrically pumping each of the light emission regions separately, so as to produce individually controllable light emission at each of the light emission wavelengths.
2. A LED of claim 1 , comprising insulating regions disposed in the semiconductor heterostructure between the electrical contacts for electrically insulating adjacent electrical contacts from each other.
3. A LED of claim 2 wherein the light emission regions are disposed in ascending order of the light emission wavelengths from the output facet on along the waveguide.
4. A LED of claim 2 wherein the plurality of light emission regions includes at least two light emission regions of which a region having a greater light emission wavelength extends along the waveguide at a greater length.
5. A LED of claim 2 wherein the plurality of light emission regions includes at least two light emission regions of which a region further away from the output facet extends along the waveguide at a greater length than the region that is closer to the output facet.
6. A LED of claim 1 wherein the semiconductor heterostructure comprises a cladding layer disposed over the plurality of light emission regions, and wherein:
the electrical contacts are disposed over the cladding layer each in electrical communication with a different one of the light emission region; and,
the cladding layer comprises:
conducting regions for conducting electrical current from the electrical contacts through respective light emission regions, and
insulating regions for preventing the electrical current from each of the electrical contacts to flow through more than one of the light emitting regions.
7. A LED of claim 6 wherein the insulating regions of the cladding layer comprise proton implanted material.
8. A LED of claim 6 wherein there is at least 1 Kilo Ohm electrical resistance between any two of the electrical contacts.
9. A LED of claim 6 wherein the semiconductor heterostructure comprises a AlGaAs/Gas, InGaAsP/InP, or InAlGaAs/InP heterostructure having differing material compositions within the light emitting regions.
10. A LED of claim 6 wherein each of the light emitting regions comprises a p/i/n heterojunction wherein a middle intrinsic layer is sandwiched between a p-doped layer and an n-doped layer, and wherein each of the light emitting regions has a different bandgap in at least the intrinsic layer thereof.
11. A LED of claim 1 wherein the output facet comprises an anti-reflection coating.
12. A LED of claim 1 wherein the waveguide is slanted with respect to the output facet thereof to reduce back reflections.