Grup de Dinàmica no Linial, Òptica no Linial i Lasers (DONLL), Departament de Física, E.S.E.I.A.A.T. Universitat Politècnica de Catalunya, Colom 11, E- 08222 Terrassa, Spain.
Grup de Propietas Físiques dels Materials (GRPFM), Departament de Física, E.T.S.E.I.B. Universitat Politècnica de Catalunya, Diagonal 647, E-08028 Barcelona, Spain.
Phys Rev E. 2017 May;95(5-1):052704. doi: 10.1103/PhysRevE.95.052704. Epub 2017 May 30.
In this paper, we report the temperature behavior of an optimized disordered photonic system-based liquid crystal by means of heat capacity and refractive index measurements. The scattering system is formed by a porous borosilicate glass random matrix (about 60%) infiltrated with a smectogenic liquid crystal (about 16%) and a small amount of laser dye (0.1%). The rest of the scattering system is about 24% air, giving rise to a high refractive index contrast scattering system. Such a system has the functionality to change the refractive index contrast with temperature due to the liquid crystal temperature behavior. The system, optically pumped by the second harmonic of a Q-switched Nd:YAG pulsed laser working at 532 nm, exhibits random laser action, the threshold of which depends upon the liquid crystalline mesophase. Temperatures of existence of the smectic-B phase correspond to the most optimized random laser. In such a mesophase, the transport mean free path has been determined as about 16 μm in a coherent backscattering experiment.
本文通过热容和折射率测量，报道了一种优化的基于无序光子系统的液晶的温度行为。散射系统由多孔硼硅酸盐玻璃随机基质（约 60%）渗透进向列相液晶（约 16%）和少量激光染料（0.1%）组成。散射系统的其余部分约为 24%的空气，形成了高折射率对比度的散射系统。由于液晶的温度行为，这样的系统具有随温度改变折射率对比度的功能。该系统由工作在 532nm 的调 Q 钕：钇铝石榴石脉冲激光器的二次谐波光泵浦，表现出随机激光行为，其阈值取决于液晶中间相。近晶 B 相的存在温度对应于最优化的随机激光。在这样的中间相中，在相干背散射实验中已经确定了约 16μm 的输运平均自由程。
