Open AccessPolarized white light from LEDs using remote-phosphor layer sandwiched between reflective polarizer and light-recycling dichroic filter
Author(s) -
Ji Hye Oh,
Su Yang,
Young Rag
Publication year - 2013
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.21.00a765
Subject(s) - phosphor , polarizer , optics , dichroic glass , dichroic filter , optoelectronics , materials science , polarizing filter , polarization (electrochemistry) , optical filter , brightness , luminous efficacy , circular polarization , color rendering index , physics , wavelength , layer (electronics) , birefringence , nanotechnology , chemistry , microstrip
This study introduces an efficient polarized, white phosphor-converted, light-emitting diode (pc-LED) using a remote phosphor film sandwiched between a reflective polarizer film (RPF) and a short-wavelength pass dichroic filter (SPDF). The on-axis brightness of polarized white light emission of a RPF/SPDF-sandwiched phosphor film over a blue LED, showed greater recovery than that of a conventional unpolarized remote phosphor film over blue LED, due to the recycling effect of yellow light from an SPDF. The relative luminous efficacy of an RPF/SPDF-sandwiched phosphor film was made 1.40 times better by adding an SPDF on the backside of an RPF-capped phosphor film. A polarization ratio of 0.84 was demonstrated for a white LED with an RPF/SPDF-sandwiched phosphor film, in good agreement with the measured results from the RPF-only sample.