High luminance tapered diode lasers for flying-spot display applications
Proc. SPIE, vol. 8280, no. 82800E (2012).
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Flying-spot display applications require high luminance (> 100 TCd/m²) red-emitting lasers. High luminance is defined as a high optical output power and a nearly diffraction limited beam quality at a wavelength with a good visibility of the human eye. Diode lasers, with all their beneficial properties such as direct modulation capability, small size and good electro-optical efficiency, are so far unable to achieve such high luminance, due to catastrophic optical mirror damage (COMD) caused by high facet loads. We will present tapered diode lasers emitting near 635 nm with a larger vertical waveguide to lower the facet load and to alleviate the COMD risk. The lateral structure consists of an index-guided ridge waveguide section for lateral mode filtering, and a gain-guided tapered section for the amplification of radiation and a further reduction of the facet load. The tapered lasers are mounted p-side down on diamond heat spreaders and on copper heat sinks. We achieved an optical output power of 1.1 W at 636 nm at a laser temperature of 5°C. The emitted beam has a nearly diffraction limited (M2 1/e² < 2) central lobe with a high power content (PCL > 75%). At 636 nm the eye sensitivity is 142 lm/W according to the CIE 1931 photopic eye response curve (v?). Hence, we achieved a luminous flux of > 100 lm and a luminosity of 150 TCd/m², thus taking a first step towards diode-laser-based flying-spot displays.
Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Straße 4, D-12489 Berlin, Germany
high-power, high-brightness, high-luminance, tapered laser, diode laser, red-emitting, projection light source.