Facilitating Remote Chemical Sensing With Random Raman Lasing
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Title: FACILITATING REMOTE SENSING VIA RANDOM RAMAN LASINGABSTRACTNontechnical Description: The driving motivation for this proposal is the growing necessity for chemically specific remote sensing (standoff detection) and deep tissue optical imaging. From remote assessment of powders on the ground to optical biomedical imaging, there is a need to evaluate the chemical composition of materials a turbid medium. Vibrational spectroscopy has proven to be successful in identifying chemicals in complex medium. However, the strength of the signal is often considered as a major limitation. The proposed research program aims at overcoming those major disadvantages by utilizing a recently discovered effect of stimulated Raman emission in disordered medium. It allows increasing the signal by an astonishing value of 106-109 making it possible simple and seamless remote chemical sensing of powders km''s away from the target. The proposed program will have a profound effect on environmental science, biomedical science and medical diagnostic imaging, and homeland security. The novel operating principle of the proposed device and technology and methods, which will be used in the device design and construction, will positively affect a number of research and application areas where light scattering effects are important. Just a single impending application of biomedical imaging device utilizing stimulated Raman scattering enhancement in randomly scattering tissues can potentially affect the lives of more than a billion people by providing a simple access to the chemical composition of deep-laying tissues. From the educational standpoint, proposed program will provide unmatched opportunities for training and professional development of the students directly involved in the research, significantly advancing their future career prospects. In particular, the program will expose the students to the "full cycle" of multidisciplinary research, from computational simulations to sample preparation and characterization, from initial formulation of analytical description of the observed phenomena to the follow-up iterative instrument optimization, from a fundamental idea to a real-life practical application. From the outreach perspective, the program presents several thrusts aimed at school-aged students and their teachers. Texas A&M University is located in the middle of the fastest growing, predominantly Hispanic-populated region in the US, and several activities will be specifically targeting the diverse student population.Technical Description: The proposed program builds up on the recent advances in computational science, engineering, optical sciences and chemistry to introduce a transformative approach for remote sensing and biomedical imaging through scattering medium. The proposed program is built on those preliminary results and has a major research objective of fundamental understanding the mechanisms and limitations of efficient nonlinear optical interactions in random media. To accomplish this goal, we will:(1)Fundamentally understand the mechanism, conditions and limitations of stimulated Raman scattering in random media. We will use both the developed computational and experimental tools to investigate the effects of absorption and scattering parameters of the media, the effects of inhomogeneities and inclusions, as well as a broad range of excitation parameters, such as wavelength, pulse duration and beam shape, on the threshold and efficiency of stimulated Raman scattering in random media.(2)Explore the possibility of controlling random Raman lasing using temporally and spatially shaped laser pulses. In many practical situations, random media does not vary appreciably over time. It creates an opportunity to optimize the wavefront of the incident radiation to enhance the nonlinear interaction inside the medium.(3)Utilize the developed concept of random Raman lasing for remote sensing and deep tissue biological imaging. We will use the results of Aims 1-2 to design a practical system for remote chemical sensing and deep tissue biological imaging.