Lasing actions from a liquid crystalline polymer blend

Abstract

We report lasing actions from fluorene-based copolymer blends with liquid crystallinity in waveguide geometry. Fluorene-based light emitting polymers, poly[2,7-bis(p-stiryl)9,9 ' -di-n-hexylfluorene sebacate] (PBSDHFS) and poly(9,9 ' -di-n-hexyl fluorenediylvinylene-alt-1,4-phenylenevinylene) (PDHFPPV), and a laser dye, 4(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM) were used in this study. We employed Forster type energy transfer from a liquid crystalline donor to a non-crystalline acceptor to tune the color and obtain low threshold for gain narrowing. We obtained a low-threshold energy (similar to 20 nJ/cm(2) per pulse) for gain narrowing of PBSDHFS/PDHFPPV (98:2, by wt.) blend film. PBSDEFS/PDHFPPV/DCM (99:2:2, by wt.) blend film possesses a threshold energy of similar to 14 muJ/cm(2) per pulse, while the PDHFPPV/DCM blend film did not per pulse. Forster excitation energy transfer played the most show gain narrowing even at a pump energy as high as 12 mJ/cm(2) important role in improving the performance of lasing actions and tuning the output colours. (C) 2001 Elsevier Science B.V. All rights reserved.