High-Intensity Solid State White Laser Diode

Brief Description

A solid state white lighting device consisting of a blue laser diode that emits light onto a single crystal phosphor, resulting in the emission of high-intensity white light. 

Background

Conventional LED white light emitters typically suffer from efficiency droop as electrical current increases; this results in less efficient devices when run at high power. A large number of LEDs are usually required to preserve the efficiency of an illuminator constructed with LEDs. Laser diodes, in contrast, do not suffer from this efficiency droop and thus can be run at much higher power without increasing loss of efficiency. However, conventional powdered phosphor wavelength converters must be held in matrix of a polymer material, which is susceptible to damage at the high power density that is achievable at high efficiency when using a laser diode as the excitation source. 

Description

UC Santa Barbara researchers have devised a solid state white lighting device consisting of a blue laser diode that emits light onto a single crystal phosphor, resulting in the emission of high-intensity white light. The single crystal phosphor absorbs some of the laser diode emission and emits a band of longer wavelength light. The combination of the remaining blue laser emission with the longer wavelength phosphor emission results in white light. Use of a single crystal phosphor allows for the emission of greater than 1100 lumens of white light without damage or degradation to the materials. This enables the replacement of a traditional incandescent light bulb with a single laser diode requiring much less epitaxial wafer area than common LED-based white light sources, which usually consist of 10-20 LEDs. 

Advantages

·         No damage, degradation, or loss of efficiency with increasing power

·         Minimizes number of diodes needed for very high power emission

·         Much less epitaxial wafer area

Applications

·         Laser diodes (LDs)

Patent Status