We demonstrate a first-of-its-kind efficient chirped pulse amplification of broadband mid-IR (4-5 μm) femtosecond seed pulse (230 ps, 4μJ) generated in AgGaS2 based OPA driven by Cr:forsterite laser in multi-pass Fe2+:ZnSe amplifier optically pumped by solid-state Q-switched Cr:Yb:Ho:YSGG laser (2.85 μm, 30mJ, 5Hz, 0.6 J/cm2). The system delivers 1.2 mJ at pulse duration of 230 ps. Straightforward compression to 150 fs pulse is achievable with 70% efficiency using diffraction grating pair with peak power of about 6 GW. Further non-linear compression in a bulk CaF2 due to the SPM and anomalous GVD should provide the enhancement of peak power up to 20 GW. Possible routes to reach sub-TW and even TW power level in mid-IR are discussed.
Performance capabilities of the developed multifrequency lidar system based on the pulsed chain chemical DF laser are presented in the paper. The purpose of the research and development is the creation of a lidar for the detection and recognition of aerosol impurities in the atmosphere, and the main attention is paid to realization of these resources of the system. Based on the numerical modeling data, the restrictions to the statement of the recognition problem are formulated. It is shown that the lidar performance characteristics allow to detect and to recognize aerosol impurities in the atmosphere for distances of up to 10 - 15 km.
One of the most actual problems in monitoring of the atmosphere is the recognition of chemical composition and microphysical characteristics of atmospheric aerosol impurities. In the present work the opportunities of lidar system based on multifrequency pulsed chain chemical DF laser (λ = 3.6 - 4.2 μm) are considered from this point of view. With the purpose of working-out of the requirements to the primary performances of lidar system, model experiments are executed as to the problem of recognition of aerosol impurities in the atmosphere with the use of DF-laser radiation lines. The obtained results and their analysis are presented in the paper.
The expected energetic performances are presented for amplification of short pulses (approximately 10-12 s) either directly in chain pulsed chemical laser (PCL) active medium, or in active media created by optical pumping of resonantly absorbing molecules by radiation of PCL. The calculations were based on the data for PCL energetic and amplifying performances and also on the data for pumping of N2O molecules by HF laser radiation, both being obtained by us earlier. For amplifying a short pulse in DF-CO2 PCL active medium, the energy output of 6J/l is achievable, while 8 - 10 J/l is attainable for regenerative amplification in HF(DF) laser (50 J/l(DOT)atm - under free oscillation conditions for both). For regime of optical pumping, the energy of N2O short-pulse radiation can make 10% of pump (PCL output) energy. A series of other promising three- and four-atomic molecules is considered. The comparison of various variants of embodying of superpowerful laser systems based of chain chemical lasers is carried out. The conception of construction of short- pulsed laser systems with radiation energy of up to 104 J is submitted with the expectation of their using for creation of dense relativistic plasma, as new perspective object of researches, and for realization of laser fusion.
The recognition of composition and of microphysical characteristics of aerosol impurities is one of the most urgent tasks in monitoring of atmosphere. Some approaches to its solution are considered in the work. At first stage we were limited to five substances: fine-dispersion water and dust as background aerosol components of atmosphere; coarse- dispersion tributilamin, turbine oil and petroleum as possible impurities. Tributilamin was chosen as spectral analog of V gases. The modeling of input spectra and the recognition were carried out on 12 discrete lines in 2.9 - 4 micrometers spectral rage. As is well known, in this range the considered impurities have the pronounced spectral dependences of aerosol backscattering, the so-called spectral resonances. Spectra of aerosol backscattering for these substances were calculated with Mie theory. We applied evolutionary algorithm (genetic algorithm) and also more traditional optimization methods, namely gradient descent method, for recognition procedure. The comparative analysis of the mentioned methods was done; the concrete results of recognition and the dependence of recognition efficiency on the number of wavelength channels and on the accuracy of spectrum recording are given.
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