Karsten Auen

Visible lasers for mobile projection

Visible laser sources are attracting considerable interest to enable ultra-small, embedded laser scanning projection devices. We report recent progress on the development of red, green and blue semiconductor based laser sources. Red and blue colours are achieved by edge-emitting laserdiodes, whereas green uses frequency doubled optically pumped semiconductor lasers. Green lasers turned-out to be on the critical path for the technical and commercial success of laser displays. Because all current approaches are based on frequency doubling, the green source is the major contributor of cost, size and power consumption. Important parameters like size, efficiency, output power, beam quality, and modulation bandwidth are discussed.

Progress in ultra-compact green frequency doubled optically pumped surface emitting lasers

Compact, stable and efficient green lasers are of great interest for many applications like mobile video projection, sensing, distance measurement and instrumentation. Those applications require medium values of output power in the 50mW range, good wall-plug efficiency above 5 % and stable operation over a wide temperature range. In this paper we present latest results from experimental investigations on ultra-compact green intracavity frequency doubled optically pumped semiconductor InGaAs disk lasers. The green laser setup has been limited to a few micro optical and semiconductor components built on a silicon backplane and fits within an envelope of less than 0.4 cc. An optical frequency looking scheme in order to fix the fundamental wavelength over varying operating conditions like changing output power and ambient temperature has been applied. The cavity has been optimized for fast modulation response and high efficiency using quasi-phase matching non-linear material. Recent data from cw and high-frequency characterization is presented.