Distributed feedback and random lasing in DCNP aggregates dispersed in a polymeric layer

Here, we report on the realization of random lasing (RL) and distributed feedback (DFB) lasing in a layer of luminescent 3-(1,1-dicyanoethenyl)-1-phenyl-4,5-dihydro-1H-pyrazole (DCNP) organic nonlinear optical dye that has been dispersed in a poly(methyl methacrylate) (PMMA) matrix. The RL phenomenon appears due to the presence of spontaneously formed micro- and nano-crystals of DCNP in the bulk of the PMMA during the sample preparation. DFB can be realized in an optical system by using degenerated two-wave mixing in the pumping beams. The period of the interference pattern can be easily changed by changing the intersection angle of the pumping beams, resulting in a real time, fully reversible method of DFB lasing emission tuning. Because of the two neighboring stimulated emission bands of DCNP, it is possible to tune the lasing wavelength over a long range of about 65 nm.