Light Amplification in Derivatives of Pyrazoline-Based Systems

Here we report on experimental results characterizing stimulated emission (SE) and random lasing (RL) phenomena in two new pyrazoline derivatives (PRDs) in comparison with earlier studied 3-(1,1-dicyanoethenyl)-1-phenyl-4,5-dihydro-1H-pyrazole (DCNP) dye. Both phenomena were observed in thin films of poly(methyl methacrylate) containing selected dyes upon excitation with 6 ns light pulses delivered by a doubled in frequency Nd:YAG laser (λ = 532 nm, f = 10 Hz). We also report on photodegradation process taking place in the samples during observation of SE and RL and estimate average lifetimes in each case. The pumping threshold levels for observation of random lasing emission amounted from about 1.5 mJ/cm 2 to nearly 70 μJ/cm 2, depending on pyrazoline dye and for stimulated emission from 16 mJ/cm 2 to 5 mJ/cm 2, respectively. The resonator lengths related to the RL phenomenon were estimated using the power Fourier transformation method.