Two-photon excited stimulated emission at ~617 nm has been achieved in an organic chromophore solution pumped at 1064 nm. The stimulated emission can be observed only in the forward and backward directions and is characterized by its high directionality and spectral narrowing. The solution was illuminated simultaneously with a strong 1064-nm pump beam and a 1064-nm weak signal beam to form an induced Bragg grating. As the strong pump beam itself induced the backward two-photon excited stimulated emission, which was a reading beam, we observed backward nondegenerate four-wave mixing (NFWM). The newly generated wave by the NFWM has the same frequency as the reading beam. Due to the phase mismatching, this newly generated coherent wave was not exactly counter-propagating to the signal wave.
© 2005 Chinese Optics LettersPDF Article