Novel AlGaAs/CaF2 SESAM Device for Ultrashort Pulse Generation


A novel ultrabroadband AlGaAs/CaF2 semiconductor saturable absorber mirror (SESAM) covering nearly the entire Ti:sapphire gain spectrum is demonstrated. This device supports sub-10-fs pulse operation of a laser. In contrast to previous SESAMs of comparable bandwidth, our device can be monolithically grown by molecular beam epitaxy and requires no post-growth processing. GaAs is used as semiconductor saturable absorber material. The high defect concentration of the material is due to the lattice-mismatched growth on a fluoride surface with (111) orientation. With a time response of 1.2 ps for carrier trapping, a saturation fluence of 36 μJ/cm2 and a modulation depth of up to 2.2%, the GaAs saturable absorber is well-suited for all-optical switching in SESAM devices used for ultrashort pulse generation.

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Correspondence to Silke Schön.

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Schön, S., Gallmann, L., Haiml, M. et al. Novel AlGaAs/CaF2 SESAM Device for Ultrashort Pulse Generation. MRS Online Proceedings Library 692, 771 (2001).

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