The electric field change of a femtosecond mid-infrared (MIR) pulse reflected by a new type of Bragg mirror is directly measured by time-resolved cross-correlation spectroscopy. The refractive-index contrast of the plasma Bragg mirror is achieved by use of different doping levels of only one type of semiconductor material (n<sup>+</sup> -doped GaAs and undoped GaAs). The direct measurement of the time dependence of the electric field of a reflected MIR pulse permits the observation of a noninstantaneous response of a Bragg mirror compared with a metallic surface, which is due to the penetration of the pulse into the multilayer structure.
© 2001 Optical Society of America
(300.6240) Spectroscopy : Spectroscopy, coherent transient
(300.6250) Spectroscopy : Spectroscopy, condensed matter
(300.6340) Spectroscopy : Spectroscopy, infrared
(300.6500) Spectroscopy : Spectroscopy, time-resolved
(320.7150) Ultrafast optics : Ultrafast spectroscopy
R. Bratschitsch, T. Müller, N. Finger, G. Strasser, K. Unterrainer, and C. Sirtori, "Monitoring the ultrafast electric field change at a mid-infrared plasma Bragg mirror," Opt. Lett. 26, 1618-1620 (2001)