Optical device with wavelength selective reflector
View Patent ↗Techniques are disclosed for transmitting electromagnetic radiation from LED devices, such as ultra-violet, violet, blue, blue and yellow, or blue and green, fabricated on bulk semipolar or nonpolar materials with phosphors. The starting material include polar gallium nitride.
1. An optical device comprising:
a substrate having an upper surface;
a light emitting diode (LED) which emits light at first selected wavelengths, the LED being mounted on the upper surface;
a spacer having reflective sidewalls also mounted on the upper surface to surround the LED;
a wavelength selective reflector disposed above the upper surface and the LED for preventing substantially all light at the first selected wavelengths from escaping from the optical device and allowing substantially all light at second selected wavelengths to pass through it and escape from the optical device; and
wavelength conversion material disposed between the upper surface and the wavelength selective reflector, whereby the wavelength conversion material in response to light at the first selected wavelengths emits light at second selective wavelengths.
2. The device of claim 1 wherein the wavelength selective surface comprises dielectric material.
3. The device of claim 1 wherein the substrate comprises silicon.
4. The device of claim 1 wherein the wavelength conversion material comprises phosphor material.
5. An optical device as in claim 1 wherein the wavelength conversion material is disposed on the upper surface.
6. An optical device as in claim 5 wherein the substrate comprises thermally conductive material.
7. An optical device as in claim 1 wherein the wavelength conversion material is disposed on the reflective sidewalls of the spacer.
8. An optical device as in claim 7 wherein the sidewalls of the spacer are angled with respect to the upper surface such that the reflective sidewalls reflect light toward the wavelength selective reflector.
9. An optical device as in claim 1 wherein the LED emits light that is not white light.
10. An optical device as in claim 9 wherein the LED emits light of about 405 nm wavelength.
11. An optical device as in claim 9 wherein the second selected wavelengths are white light.
12. An optical device as in claim 11 wherein the wavelength selective reflector has a textured surface to diffuse white light.
13. An optical device as in claim 1 further comprising an encapsulant disposed within the spacer and above the upper surface to encapsulate the LED.
14. An optical device as in claim 13 wherein the wavelength selective reflector comprises a mirror disposed only on a portion of the encapsulant above the LED to reflect light from the LED back toward the upper surface.
15. An optical device as in claim 14 wherein the portion is only a central portion of the encapsulant and wavelength conversion material is disposed on the upper surface.
16. An optical device as in claim 15 wherein light at first selected wavelengths is reflected by total internal reflection from the encapsulant not covered by the mirror.
17. An optical device as in claim 13 wherein the encapsulant has an upper surface which is configured to cause total internal reflection of the first selected wavelengths within the encapsulant.
18. An optical device comprising:
a substrate having an upper surface;
a light emitting diode (LED) device which emits light at first selected wavelengths, mounted on the upper surface;
a wavelength selective reflector disposed above the upper surface and the LED for preventing substantially all light at the first selected wavelengths from escaping from the optical device;
a layer of wavelength conversion material disposed on the upper surface around the LED, an upper surface of the wavelength conversion material being below an upper surface of the LED, whereby the wavelength conversion material in response to light at the first selected wavelengths emits light at second selective wavelengths, and wherein the wavelength selective reflector allows substantially all light at the second selected wavelengths to escape from the optical device; and
a reflective sidewall surrounding the LED.
19. The device of claim 18 wherein the wavelength conversion material comprises phosphor material.