Electrically tunable lasers made from electro-optically active photonics band gap materials

External cavity-free and electrically tunable laser made from photonics band gap (PBG) materials with electrically tunable stop band is reported. The tunable PBG materials are developed from a family of novel cholesteric liquid crystals (CLC) with electrically variable pitch that adopts a non-constant distribution in space across the CLC film. The CLC exhibits a distributed feedback cavity whose resonant frequency can be electrically varied over a spectral range wider than 300 nm. Under an optical pumping and subject to a variable electric field, a tunable laser has been demonstrated in experiment that shows a wavelength tuning over 33 nm.