Andrea Cavalleri

Abstract:

In this letter we demonstrate the possibility to determine the temporal and spectral structure (spectrogram) of a complex light pulse exploiting the ultrafast switching character of a nonthermal photoinduced phase transition. As a proof, we use a VO2 multifilm, undergoing an ultrafast insulator-to-metal phase transition when excited by femtosecond near-infrared laser pulses. The abrupt variation in the multifilm optical properties, over a broad infrared/visible frequency range, is exploited to determine, in situ and in a simple way, the spectrogram of a supercontinuum pulse produced by a photonic crystal fiber. The determination of the structure of the pulse is mandatory to develop pump-probe experiments with frequency resolution over a broad spectral range (700-1100 nm). © 2010 American Institute of Physics.

Abstract:

Saturated absorption and intervalley scattering in n-type semiconductors were observed using noncollinear THz-pump-THz probe spectroscopy with ultrabroadband probe pulses. © OSA / UP 2010.

Abstract:

The high-temperature superconductor La1.84Sr0.16CuO4 is excited with high intensity terahertz pulses tuned to the 1.9-terahertz Josephson Plasma Resonance. The strong interlayer tunneling current modulates the microscopic properties of the superconductor. © OSA / UP 2010.

Abstract:

We introduce a new scheme for single-shot characterization of the absolute-phase jitter of mid-IR pulses. The system detects phase drifts of self-phase stabilized sources; a control scheme compensating long-term drifts is also demonstrated. © OSA / UP 2010.

Abstract:

We present ultrafast resonant soft-x-ray diffraction measurements of time-dependent orbital order in the single-layer-manganite La0.5Sr1.5MnO4. These experiments reveal the appearance of a metastable phase with reduced ordering, different from any thermal state of the system. © OSA / UP 2010.