During the past decade, photonic band edge lasers based on cholesteric liquid crystals (CLCs) have attracted considerable interest as self-assembled coherent, tunable lights sources. We report on recent progress towards practical applications: (i) Electrical fine tuning of laser emission by in-plane electric fields: the field-induced distortion of the cholesteric helix allows for a controllable, continuous and reversible shift of the band edge resonances. (ii) Improvement of lasing performance by application of an electric field along the helical axis of a system with negative dielectric anisotropy: the electric field stabilizes the soft photonic structure against heating-induced distortions. (iii) PDMSenclosed LC lasers for lab-on-a-chip applications: We demonstrate the formation of a uniform planar cholesteric texture between polydimethylsiloxane (PDMS) substrates and narrow-band laser emission of a PDMS-enclosed LC laser. With PDMS being the standard material for the fabrication of microfluidic devices, this opens a simple and flexible route for the integration of coherent light sources in lab-on-a-chip designs.

Date Published: 5 March 2013
PDF: 8 pages
Proc. SPIE 8642, Emerging Liquid Crystal Technologies VIII, 864209 (5 March 2013); doi: 10.1117/12.2008373

Published in SPIE Proceedings Vol. 8642:
Emerging Liquid Crystal Technologies VIII
Liang-Chy Chien; Dick J. Broer; Vladimir Chigrinov; Tae-Hoon Yoon, Editor(s)