Liquid Crystal Lasers are now recognised [1] in many forms, band �edge, random, defect mode to name but a few. Lasing has been observed in Blue Phases, Chiral Nematic, Defect Doped Nematics and Chiral/Achiral Smectics. We have found that Long-Wavelength Band Edge Lasing in Chiral Nematics  give the highest slope efficiency (~70%), where, slope efficiency is defined as the lasing energy output/energy input/pulse [2]. We describe the background to Microscopic Liquid Crystal lasers, based on dye doped Chiral Nematics, their modus operandi and then consider the key materials properties of the liquid crystal host & cavity design that lead to such high slope efficiencies, low laser thresholds (~25nJ/pulse), narrow line widths (<0.01nm), laser outputs continuously tunable over a 450 to 850 nm wavelength range and quasi-continuous working (3kHz pulse rate) giving average powers of 5mW per pixel or laser spot. Laser pulse widths are typically 1-5ns.The birefringence, the elastic constants and the orientational order parameters of the liquid crystals and the fluorescent light harvesting dye  are the key parameters that influence markedly the performance of such LC lasers. 2-D lenslet arrays of up to 100 by 100 spots have been used to give a quasi- continuous working wide colour gamut RGB laser output [3] with powers of Watts in the far field. Such outputs may be combined to give �white light� laser based outputs. These lasers may be continuously wavelength tuned and we will discuss how they may be deposited from emulsions and ink-jet printed on to polymer substrates leading to novel laser geometries with a wide range of spectroscopic applications.[1] H.J. Coles, S.M. Morris, Nature Photonics, 4 , 676 (2010).[2] C. Mowatt, S.M. Morris, T.D. Wilkinson, and H.J. Coles, Appl. Phys. Lett. 97 ,  251109 (2010).[3] S.M. Morris, et al, Optics Express, 16  (23), 1882(2008)

Liquid crystal lasers: From materials to realization

245th National Meeting (2013)

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