Tunable liquid crystal laser using distributed feedback cavity fabricated by nanoimprint lithography

Electrical tuning of laser wavelength is demonstrated using a liquid-crystal/polymer grating fabricated by nanoimprint lithography. Laser emission occurs at a wavelength near 700 nm, which corresponds to the first order of a 200 nm period grating. With increasing applied voltage, the lasing spectrum begins to shift to shorter wavelengths at 10 V, and then a 10 nm shift is achieved with an applied voltage of 30V. This is due to the refractive index change of the liquid crystal in the trench of the polymer grating by field-induced molecular reorientation. (c) 2008 The Japan Society of Applied Physics.