Periodic Photonic Structures in Lithium Fluoride

Lithium Fluoride (LiF) presents interesting optical properties and it has been proposed as an active optical material for colour centre (CC) lasers and amplifiers. The use of a grating to reduce the laser threshold and to narrow the line-width has also been demonstrated. More recently, LiF gained increased attention due to its unique characteristics as x-ray imaging detector for high resolution microscopy and for the development of CC lasers using gratings induced by high energy femtosecond laser pulses. We present a review of our recent work in the production of photonic structures, like photo-induced Bragg gratings and wave-guides either by laser CW illumination or by femtosecond laser irradiation. CW laser illuminated gratings were written in both coloured LiF crystals and films. Gratings and wave-guides are characterized using confocal microscopy, optical absorption and emission spectroscopy, near field scanning, scattering and insertion loss measurements.