Cholesteric liquid crystal laser with wide tuning capability

Abstract

This letter examines a planar cholesteric cell ͑CLC͒ doped with two collocated laser dyes as a one-dimensional photonic crystal. Adding phototunable chiral material ͑AzoB͒ allows the CLC photonic crystal to be lased at the band edges of the photonic band gap with a tuning range of over 100 nm. Tuning is performed by irradiating the chiral AzoB material with UV light, causing the material to undergo trans-cis isomerization in the CLC film. The tuning range is the visible region from 563 to 667 nm. Moreover, the tuning is reversible.

Lasing Characteristics of Dye-Doped Cholesteric Liquid Crystal

“…Tsung-Hsien Lin et al examined a planar cholesteric cell doped with two laser dyes as a one-dimensional photonic crystal [36]. When photo tunable chiral material was added, the cholesteric liquid crystal was lased at the band edges of the photonic band gap with a tuning range of over 100 nm.…”

Tunable and Memorable Optical Devices with One-Dimensional Photonic-Crystal/Liquid-Crystal Hybrid Structures

“…Among them, the PBG of CLCs depends on the LC and chiral parameters. The tunable CLC PCs can thus be realized by adjusting the external factors such as temperature (Morris et al, 2005;Hung et al, 2000), light irradiation (Bobrovsky et al, 2003;Lin et al, 2005), or electric field (Choi et al, 2009;Lin et al, 2005;Yu et al, 2005). Some other tunable PCs based on FLC (Kasano et al, 2003) or BP LC (Yokoyama et al, 2006) have also been demonstrated.…”

Different Approaches of Employing Cholesteric Liquid Crystals in Dye Lasers

“…Since the publication of this work, there have appeared a number of papers concerned with phototunable CLC [33][34][35][36][37]. In [36,37], the reversible tuning was performed using a trans-cis photoisomerization of the chiral azo component of a cholesteric liquid-crystal mixture.…”

“…In [36,37], the reversible tuning was performed using a trans-cis photoisomerization of the chiral azo component of a cholesteric liquid-crystal mixture. Lin et al [37] achieved a change in the helical pitch up to 110 nm through exposure to light from an ultraviolet lamp for 20 min. However, the reverse relaxation transition to the initial trans state was observed only within 20 hours.…”