Proceedings Article | 25 February 2020
KEYWORDS: Crystals, Laser crystals, Waveguides, Photonic crystals, Prisms, Projection systems, Semiconductor lasers, Polishing, Reflectivity, Semiconducting wafers
While LEDs have been the used in many of the high “lumen” applications, they are not “bright” enough for projectors, entertainment spotlight, etc., where the etendue of the systems are small. Laser phosphor system have been developed in the last 10 years using mostly silicone, some ceramic and glass, phosphors for low power applications. For higher power systems such as projectors, phosphor wheels are used so as to dissipate the heat in a larger area, allowing the operating temperature to be below the damage and droop threshold of the phosphor material. For silicone phosphor, the outputs are usually limited by the bonding materials. This paper presents static, without a rotating wheel, high power laser excited crystal phosphor system in which the crystal phosphor has a very high damage and drooping threshold temperature. Using 2 laser diode arrays, a total of 170 W of blue laser light is focused into an area of smaller than 2 mm in diameter, giving a power density of over 54 W/sq. mm., which is limited by the available laser power. It is expected to increase in the near future with higher power laser sources, development of homogenizing and diffusing optics at the input, and micro and photonic structures at the output surfaces. For projector applications, this high power static crystal phosphor system can replace the current phosphor wheel, in most case, directly without redesign of the other projector components in terms of mechanical, optical, and electronics. The crystal phosphor materials have been developed and manufactured by Taiwan Color Optics, Inc.
