Abstract. In this paper we report the status of the experiment MIR (Motion Induced Radiation), aimed at the experimental verification of the dynamical Casimir effect. The stringent theoretical requirements to observe the effect are satisfied in a scheme in which the conductivity of a semiconductor inside a superconducting microwave resonant cavity is varied in time. Free carriers in the semiconductor are periodically excited and recombine at 5 GHz. In this process vacuum and thermal photons are parametrically amplified in a time interval of 200-500 ns.

Abstract.In this paper the status of the experiment MIR is reported. This experiment aims at measuring for the first time the Dynamical Casimir Effect by using an effective motion of a wall of a superconducting microwave resonant cavity. Effective motion is produced by periodic illumination of a semiconductor slab by means of a ultra-high-frequency amplitude modulated laser.

We report the results of the investigation on a passively mode-locked Yb(3+):CaGdAlO(4) laser, pumped by a single transverse mode laser diode emitting 350 mW at 980 nm. This particular pump source allows efficient pumping with a nearly TEM(00) beam and minimal thermal load, making the optimization of the mode-locking performance more straightforward than with higher-power multimode beams. Indeed, using a semiconductor saturable absorber mirror and extra-cavity dispersion compensation, pulses as short as 40 fs (31-nm spectrum) have been measured, tunable across 20 nm with 15-mW output power. Slightly longer Fourier-limited 46-fs pulses with 33 mW output power directly from the oscillator have been achieved, using a different saturable absorber mirror. Such overall performance, especially considering these are among the shortest pulses generated in diode-pumped ytterbium lasers, confirms the excellent qualities of Yb(3+):CaGdAlO(4).

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