Distributed feedback laser with optoelectronic tunability in dye-doped cholesteric liquid crystal with coated photoconductive layer

This work investigates, for the first time, an optoelectronically tunable distributed feedback laser that is based on a planar DDCLC cell with a coated photoconductive (PC) layer. Experimental results show that the CLC reflection band and the lasing wavelength of the DDCLC can both be tuned optoelectronically by varying the intensity of one irradiating CW green beam or the magnitude of the applied dc voltage. The tunability of the DDCLC laser depends on the controllability of the optoelectronic properties of the PC layer and, therefore, on the voltage dropping on the CLC layer. Therefore, the CLC pitch can be controlled by exploiting the optoelectronically induced electrohydrodynamic effect which causes the spatially periodic deformation of the CLC structure. In addition, the dependences for other critical lasing parameters, e.g., energy threshold, lasing efficiency, and lasing linewidth, on external controlling signals are also measured and discussed in the current study.