Polarized Spectra of Amplified Spontaneous Emission and Gain for Glycerin Solutions of Dye Rhodamine-640

Abstract

The polarized spectra of the intensity and gain of the amplified spontaneous emission (ASE) have been measured for two glycerin solutions of a laser dye Rhodamine-640 (RhA and RhB with concentrations of 3 × 10 −4 and 3 × 10 −3 M/L, respectively). The solutions were pumped by the linearly polarized light. The ASE polarization ratio r strongly depends on the pump pulse energy, which is continuously increasing up to one for RhA and saturating at the level of r ≈ 0.8 for RhB. The gain spectra have been measured by variation of the amplification length for ASE. With increasing pump beam energy, the maximum gain continuously grows for RhA and saturates for RhB, reaching the values of 14-15 and 6 cm −1 for both materials for the polarization parallel to the pump beam polarization. At a particular spectral point, the gain coefficient has also been measured by the direct amplification of the probe beam of a microlaser on a cholesteric liquid crystal.