High power gain for stimulated Raman amplification in CuAlS2

Cataloged from PDF version of article.The spontaneous Raman spectra of the chalcopyrite structure crystal CuAlS2, which is promising for nonlinear optical applications, has been investigated at 8 and 300 K. The main aim of this study is to compare the absolute spontaneous Raman scattering efficiency in CuAlS2 crystals with that of their isomorphous analog, zinc-blende structure GaP crystals, known as one of the most efficient materials for amplification. Observation of a high value of absolute scattering efficiency S/L d Omega (where S is the fraction of incident power that scatters into the solid angle d Omega and L is the optical path length with S/L d Omega=9.5X10(-5) cm(-1) sr(-1)), together with relatively narrow linewidth (Gamma=5.1 cm(-1), full width at half maximum at room temperature and Gamma=1.5 cm(-1) at 8 K for the strongest Gamma(1) phonon mode of CuAlS2 at 314 cm(-1)) indicate that CuAlS2 has the highest value of the stimulated Raman gain coefficient g(s)/I where I is the incident laser power density, The calculated value of this gain is g(s)/I=2.1X10(-6) cm(-1)/W at 300 K and 50X10(-6) cm/W, at 8 K for 514.5 nm laser excitation, and is larger than those for the appropriate vibrational modes of various materials (including GaP, LiNbO3, Ba2NbO5O15, CS2 and H-2) investigated so far. The calculations show that cw Raman oscillator operation in CuAlS2 is feasible with low power threshold of pump laser. (C) 1996 American Institute of Physics

Resonant raman scattering in complexes of nc-Si/SiO₂ quantum dots and oligonucleotides

We report on the functionalization of nanocrystalline nc-Si/SiO2 semiconductor quantum dots (QDs) by short d(20G, 20T) oligonucleotides. The obtained complexes have been studied by Raman spectroscopy techniques with high spectral and spatial resolution. A new phenomenon of multiband resonant light scattering on single oligonucleotide molecules has been discovered, and peculiarities of this effect related to the nonradiative transfer of photoexcitation from nc-Si/SiO2 quantum dots to d(20G, 20T) oligonucleotide molecules have been revealed