RICERCA ITALIANA     

Temporal compression of laser radiation pulses by coherent control

Università degli Studi di Firenze

Abstract

In this project, we propose a joint experimental and theoretical study of the temporal compression of a laser pulse through coherent control techniques based on Electromagnetically Induced Transparency. This process allows the control of the optical response of the medium and it is a particular case of the so called coherent control of the medium polarization that is a recent large topic of research. The groups proponent the present research project have a long standing experience in this topic, both experimentally and theoretically.

The experimental research will be devoted to the observation, the study and the optimization of the compression process in the visible spectral region and in the nanosecond regime, using samples of hot alkaline atoms in the gas phase in heated cell. The goal of the theoretical study is to establish a realistic theoretical/numerical model that provides a deep understanding of the limits that can be achieved and that enables to predict and reproduce the obtained experimental results. The theoretical and experimental activities will be strongly linked in order to obtain an optimal design of the experiments, to explain the observed results and to study the limits that can be achieved using the proposed technique. A tight interaction between the two groups will be crucial to the success of the project.

In prospect, the accomplishment of the present project would provide a solid base for a further study on temporal >>>

Principal Investigator

Stefano CAVALIERI Università degli Studi di FIRENZE

Research Objectives

This research project aims at the study, both theoretical and experimental, of the temporal compression of a radiation laser pulse by coherent control techniques based on Electromagnetically Induced Transparency.
In the proposal, one can recognize a series of goals – linked to the scheduled steps of the project (see 2.3) – that can provide the basis for a final evaluation of its succes.

The main goal is the experimental confirmation of the results expected according to our theoretical model (Ref. 46 e 47 of 2.2a). This implies the observation of the compression process using samples of hot atoms in gas phase in cells and monomode laser pulses in the visible spectral region and nanosecond temporal regime.

Further explicit goals are the experimental finding of the limits that can be attained using the proposed technique in terms of intensity and temporal duration of the compressed pulse and the realization of a realistic theoretical/numerical model – that includes in our previous work (Ref. 46 e 47 of 2.2a) concomitant processes so far ignored – in order to predict and to reproduce the experimental results.

An implicit goal that would be automatically reached, once satisfied the previous ones, is the acquisition of experimental techniques, strumentation and theoretical knowledge that could provide the ground for a future extention of the proposed study to the vacuum and extreme ultraviolet spectral regions. It is worth to >>>

Timescale

24 months

National and international background

Advances in optics have frequentely arisen through the delopment of new materials with optimized optical properties. For instance the introduction of new optical crystals in the 1970's and 80's led to substancial increases in non-linear optical conversion efficencies into the ultraviolet (UV) region of the electromagnetic spectrum. In recent years coherent preparation of the medium has been proposed as a new avenue to produce remarkable changes in the optical properties of a gas phase atomic or molecular medium. The cause of the modified optical response of an atomic medium in this case is the laser induced coherence of atomic states which leads to quantum interferences between the excitation pathways that control the optical response.
The control of the optical response of the medium is a particular case of the so called coherent control of the medium polarization that leads to the control of many processes such as excitation, photoionization, photodissociation and in general transition to bound or continuum state in atomic, molecular and solid state media studied both for foundammental research and for spectroscopic application. (1-14).
The groups proponent the present research project are active in this topic since many years, both experimentally and theoretically (15-29).

More importantly, as far as this proposal is concerned, coherent control techniques allow the creation of a perfectly trasparent medium in which the speed of light can be >>>