| The stimulated Raman scattering (SRS) will occur in the Raman active material when the material is excited by pulse laser and the threshold of SRS in the material is achieved. According to the different Raman material, the Stokes and Anti-Stokes spectral lines with different frequency shifts and different orders will be formed. SRS is a very important nonlinear optical effect for generating tunable coherent radiation in visible, infrared and ultra-violet. Comparing with optical parametric oscillation (OPO) and dye laser (DL), SRS has many advantages: the Stokes output beam properties of tenability, narrow line-width, high spatial purity and relatively low cost. But the lower transition efficiency of SRS limited its real applications. In the recent decade, scientists would like to find a new type of method to enhance SRS.The energy will be stored in the excited molecules of the active material when it is excited, and at that time, the total system is in the state of population inverse. When the signal light passes through the active material, the stimulated emissionprocess will occur and pile the signal light, so the signal light will be enhanced. So when the Stokes waves serving as signal light traverse fluorescence medium with an inverted population, the Stokes waves will be increased just like the amplification of a laser beam in a laser gain medium.In this paper, we report a series of experiments on enhancement of SRS by dye fluorescence.We demonstrated that the Stokes lines of SRS of CS2 could be power enhanced by R6G dye fluorescence. The first- and second-order Stokes lines are increased respectively by 1.7 and 96.6 times relative to that of pure CS2 in experiment.To avoid the influence of self-focusing, we do the experiment on the amplification of SRS of Benzene by using R6G. The threshold of SRS of C6H6 is higher than that of CS2, and the output of SRS of C6H6 will be steady when the interaction length is long enough. With a specified concentration of R6G, the first-and second-order Stokes lines are increased respectively by 3.8land 6.1 times relative to that of pure C6H6.C3H6O is a feeble Raman medium and difficult generating SRS. When we use C3H6O as scattering medium and RB as fluorescence medium, the Stokes line of C3H6O is increased by 2.83 times relative to that of pure C3H6O. At the same time, the steady dye laser was generated in RB. The wavelength range of tunable dye laser is 575-598nm.Then the three- color laser appeared.Our experiment investigation is novel, such as detaching the fluorescence medium from Raman medium, power enhancement of SRS of CS2 by R6G, resonance enhancement of C6H6 by R6G, and the output of three- color laser et.al. The experiment results mentioned above show that the method of SRS by dyefluorescence is an effective method for improving the energy conversion. When choosing a proper SRS medium and a certain kind of fluorescence medium, the SRS medium can generate Raman laser when it is excited by pump laser, fluorescence medium will absorb the residual pump laser and amplify the Raman laser when the Raman laser and residual pump laser traverse it, then we get the output laser of frequency modulation which is good stability, narrow line-width, high spatial purity and high efficiency, It makes that the output frequency modulation laser can be got a wide application in Lidar, scientific experiments, industries and people living, such as high power tunable laser source, multi-wavelength laser showing, et.al.
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