Speckle-free phosphor-scattered blue light emitted out of InGaN/GaN laser diode with broadened spectral behavior for high luminance white lamp applications

Abstract

Ultra-high luminance lamps emitting white light with a well-scattered blue spectrum from InGaN/GaN laser diodes and a phosphor-converted yellow spectrum show speckle contrast values as low as LED. Spectral behavior of the laser diodes is analyzed to find the reason why such low values are obtained. As a result, the PWM-driven, multilongitudinal mode with dynamically broadened line-width is found to have a great effect on reducing speckle contrast. Despite using the lasers, such speckle-free lamps are considered to be very suitable for high-luminance and other various lighting applications. Copyright © 2013 The Institute of Electronics, Information and Communication Engineers.