Ring Remote Phosphor Structure for Laser-Driven White Lighting

Abstract

In this article, a ring remote phosphor (RRP) structure comprising an inverted-cone-lens encapsulant and a surrounding phosphor layer was developed and used for laser-driven white lighting. The inverted-cone-lens encapsulant in the structure redirects light from a blue laser diode (LD) to the surrounding phosphor layer, thus preventing intense light from hitting the phosphor layer on a small surface and, therefore, from considerably reducing luminous efficiency. The design of the inverted-cone-lens surface of the encapsulant was investigated, and 3-D ray-trace simulations were performed to confirm its light distributions. The RRP structure with an inverted-cone-lens encapsulant and a surrounding phosphor layer was fabricated to produce laser-driven white lighting, and the optical characteristics of the RRP structure with different phosphor concentrations were examined. The output luminous flux of the RRP samples increased with increased phosphor concentration, whereas the correlated color temperature (CCT) decreased with an increase in phosphor concentration. Therefore, the RRP structure can be used to generate efficiently high-brightness white light.