36 research outputs found
Sequentially Timed All-Optical Mapping Photography for Real- Time Monitoring of Laser Ablation: Breakdown and Filamentation in Picosecond and Femtosecond Regimes
To investigate ultrafast phenomena, a novel, ultrafast imaging technique was developed. Sequentially timed all-optical mapping photography (STAMP) performs single-shot image acquisition without the need for repetitive measurements and without sacrificing high-temporal resolution and image quality. The principle of this imaging method is based on the all-optical approach, and therefore it overcomes the temporal resolution in conventional high-speed cameras. Also, STAMP’s single-shot movie-shooting capability allows us to obtain sequential images of non-repetitive ultrafast dynamic phenomena. Here, we present the motion pictures of early stage dynamics during femtosecond laser ablation captured by two types of STAMP setup. Breakdown was induced by intense femtosecond laser pulse and monitored with a frame interval of 15.3 ps and a total of six frames. The movie clearly shows the plasma generation and expansion on glass surface. Also, filamentation was generated inside a glass and observed with a frame interval of 230 fs and total of 25 frames. These phenomena have previously only been observed by pump-probe imaging. STAMP is a powerful tool to understand precise processes of complex dynamics in ultrashort laser ablation
Practical purification scheme for decohered coherent-state superpositions via partial homodyne detection
We present a simple protocol to purify a coherent-state superposition that
has undergone a linear lossy channel. The scheme constitutes only a single beam
splitter and a homodyne detector, and thus is experimentally feasible. In
practice, a superposition of coherent states is transformed into a classical
mixture of coherent states by linear loss, which is usually the dominant
decoherence mechanism in optical systems. We also address the possibility of
producing a larger amplitude superposition state from decohered states, and
show that in most cases the decoherence of the states are amplified along with
the amplitude.Comment: 8 pages, 10 figure
Multimode Quantum Correlations in Supercontinuum Pulses
Suprecontinuum (SC) light contains complex spectral noise structure and its
accurate characterization is important for fundamental understanding of its
physics as well as for its applications. Several experimental and theoretical
noise characterizations have been performed so far. However, none of them takes
into account the quantum mechanical properties. Here, we demonstrate
experimental characterisation of quantum noise and its spectral correlations
formed in the SC light generated from a photonic crystal fiber. Moreover, by
applying an appropriate basis transformation to these correlations, we
demonstrate that the SC noise amplitude can be squeezed below the shot-noise
limit in some bases, even in the presence of excessively large nonlinearities.Comment: 10 pages, 5 figure