Recording 2nd order PQ:PMMA reflective VBG for diode laser output spectrum narrowing.

Two 2nd order PQ:PMMA reflecting VBGs with Bragg wavelengths of 488.8 nm and 525.6 nm were recorded using 532 nm as the recording wavelength. The formation of 2nd order PQ:PMMA VBG is explained and simulated based on the diffusion model of the PQ molecules in the PMMA matrix. The 525.6 nm VBG successfully served as the ECDL cavity mirror of a 522 nm diode laser and achieved more than 10000-fold output spectrum narrowing.

Study of temperature distributions in pc-WLEDs with different phosphor packages.

Phosphor converted white LEDs (pc-WLED) with different geometries, namely remote-dome, remote-plate, half-dome, and conformal-coating packages, were studied using simulations to obtain the thermal power and the temperature distribution. The results of an experiment carried out to measure the temperature distribution in these pc-WLEDs validate the simulation results. A hotspot always occurs in the phosphor region. The conformal-coating package is the most feasible choice to reduce the hotspot temperature comparing with the other geometries.