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Q: Quantenoptik

Q 23: Poster: Application of Short Pulses

Q 23.10: Poster

Thursday, April 5, 2001, 12:30–15:00, AT2

Optical limiting for femtosecond laser pulses — •Anna Nevejina, Olav Werhahn, Holger Lecher, and Uwe Siegner — Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig

Optical limiters are nonlinear optical devices whose transmission decreases as the intensity of the incident laser radiation is increased. This behavior leads to a restriction of the transmitted laser intensity. Therefore, optical limiters are extremely useful for the protection of sensitive photodetectors or the human eye. While optical limiting and the underlying mechanisms have been intensively studied with nanosecond pulses, much less is known about optical limiting on the femtosecond time scale. We present an investigation of optical limiting in ZnSe-based devices, performed with 250 fs laser pulses at 800 nm. Optical limiting results from two-photon absorption (TPA) and nonlinear refractive index changes induced by the free carriers that are generated by TPA. We will discuss how the optical design of the devices affects the limiting performance and present guidelines for the optimization of these optical limiters.