6533b870fe1ef96bd12cee5a

RESEARCH PRODUCT

Coherence in ultrashort light pulses and applications in temporal optics.

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In the last decades, the generation of lasers delivering pulses with durations in the order of femtosecond has constituted an important research topic for the Physics and Engineering communities. The characteristics of this kind of radiation, i.e., broadband spectrum, enormous temporal resolution, high peak-power with low energy average, potentially high repetition rate and high spatial coherence make it an indispensable tool in order to develop many applications in different fields of science and technology. Ultrafast laser technology is ready to offer real world applications ranging from high-tech, such us high-speed circuit testing and biological imaging, to more industrial applications like quality control. The markets that are already or will be influenced in the near future include industries as telecommunications, automotive, electronics, medical and inspection of consumer goods, to name only a few. In this direction, the so-called Space-Time analogy is an important tool for designing new schemes for ultrashort light pulse processing. It is based on the formal similitude between the diffraction of 1D light beams and the distortion of short light pulses in a first-order dispersive medium. In this Thesis, we have extended this analogy from the fully coherent to the partially coherent and quantum regimes. In the fully coherent regime in particular, we have proposed a new system for the tuning of spectral envelope of a short light pulse without altering the input profile. In addition, we have explained the phenomenon of phase-to-amplitude conversion in terms of the Fresnel images of a phase-only diffraction grating. In the partially coherent regime, we have made use of the optical coherence theory to analyze theoretically the influence of the finite source linewidth optical communication systems, as well as the distortion of optical frequency combs due to the general noise in mode-locked lasers. Alternatively, we have proposed and experimentally verified a technique for arbitrary radio-frequency and microwave waveform generation that operates with incoherent broadband light. Finally, in the quantum regime, we have recognized an analogy between the distortion of entangled photons and partially coherent pulses in dispersive media. This similarity has allowed us to point out that many quantum systems do not really require a two-photon light source, so that their complexity can be greatly reduced.