Max-planck-gesellschaft Zur F&#xf6;rderung Der Wissenschaften E. V.

Gustav Veith

Jurgen Kuhl

Ernst O Gobel

A method and an apparatus are described by producing optical radiation pulses with a duration of the order of picoseconds (10.sup.-12 s) and less using external mode locking of the longitudinal laser modes of a semiconductor laser element operating in an external resonator. In the method of the invention the gain modulation, needed for synchronous mode locking, of the active semiconductor laser element is effected by modulation of the electrical pumping current by way of a high-speed optoelectronic switch, that for its part is controlled by a mode locked master laser. The present method combines the advantages of synchronous optical pumping, as used in commercial mode locked dye laser systems, with the simple type of electrical pumping of commercially available semiconductor laser diodes, more especially double heterostructure laser diodes. It respresents a simple and economic alternative to synchronously pumped dye laser systems and considerably extends the spectral range within which radiation pulse may be produced with a duration of the order of picoseconds.

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Leinfelden-Echterdingen, Germany

Gustav Veith