Patent Number: 052084620
Section: summary

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to solid state optical sources, more specifically it relates to solid state optical sources with a wide bandwidth. 2. Description of the Related Art Solid state optical sources are used in communications involving fiber optics. The number of channels carried by a fiber is increased through wavelength multiplexing. Wavelength multiplexing requires the use of a wide bandwidth optical source. Typical solid state optical sources have a full width at half maximum (FWHM) bandwidth of 100 nm or less. A band width of 100 nm or less is insufficient for adequate wavelength multiplexing. One possible solution is to combine several solid state optical sources having slightly different wavelengths to achieve the desired bandwidth. Arranging several solid state optical sources so that they interface to a small diameter optical fiber is cumbersome and is unreliable. Another possible solution is to use a white light source, such as a lamp, in combination with a notched filter. This solution suffers from the disadvantages of size, weight and high power consumption. SUMMARY OF THE INVENTION The wide bandwidth solid state optical source comprises a solid state optical source that has a light emitting surface which emits a first light having a first FWHM bandwidth. A phosphor is positioned near the light emitting surface so that the phosphor absorbs the first light and emits a second light which has a second FWHM bandwidth that is greater than the first FWHM bandwidth. A typical phosphor can contain a material selected from the group consisting of CaS and SrS. The material can be doped with Yb. The present invention provides a wide bandwidth solid state optical source without requiring a cumbersome arrangement of multiple solid state optical sources. In addition, the present invention does not require using a white light in combination with a notched filter. The present invention provides a wide band optical source by placing a phosphor coating on a solid state optical source such as an LED or laser diode. The phosphor coating absorbs the light produced by the optical source and reemits the energy as wide bandwidth optical energy.