Alexandre Kolomenski

Spectral phase retrieval from interferometric autocorrelation by a combination of graduated optimization and genetic algorithms

We describe a method for retrieving spectral phase information from second harmonic interferometric autocorrelation measurements supplemented by the use of the observed spectral intensity. By applying a combination of graduated optimization and genetic algorithms, accurate phase retrieval of laser pulses as short as a few optical cycles was obtained from the measured autocorrelation and spectral intensity. The effectiveness of the combined algorithms is demonstrated on a set of significantly different femtosecond pulse shapes.

Tracer Detection by Laser Spectroscopy for Applications in Oil and Gas Industry

Tracer technology is very popular in petroleum engineering applications, and includes applications in reservoir characterization, reservoir modeling, improved oil recovery, etc. Most of the current tracer technology uses radioactive isotopes that are not environmentally friendly and require strict safety precautions. We propose the use of rare long-lived and stable noble gas isotopes as tracers, where instead of the decay of the radioactive material, we will use optical detection. Due to their chemical inertness, rare noble gases offer the advantage that they do not react with the environment with which they are in contact. Our research employs for the first time optical detection of tracers by collinear fast beam laser spectroscopy. It has the additional advantage that novel tracer projects based on multiple tracers can be designed in the future. In this work also the optical hyperfine structure of long lived Kr 85 was used to identify the Kr 85 tracer atoms. The technique has also been successfully applied to stable krypton isotopes. The abundance selectivity is at the one part in 10 level and the sensitivity is at a few hundred ions. This method is several orders of magnitude more sensitive than the standard nuclear decay detection. The new tracer technology offers a safer and more accurate option for applications in the oil and gas industry. The research work is currently being done in Qatar for application in Qatar’s North Field.