Growth of Nd: Gd3Ga5O12 Thin films by pulsed laser deposition for planar waveguide laser

Abstract

Pulsed laser radiation of a KrF excimer laser was used for the deposition of thin Nd3+ doped Gd3Ga5O12 (Nd:GGG) films on yttrium aluminium garnet (YAG) and sapphire single crystal substrates. By variation of PLD-parameters such as temperature and processing gas pressure, amorphous and single crystalline thin films were produced. The morphology and the composition of the grown films were investigated by optical microscopy, scanning electron microscopy and electron dispersive X-ray spectroscopy. Thickness and structural properties of the deposited films were determined by optical reflection spectroscopy and X-ray diffraction, respectively. The optical properties of grown films on different substrates were compared. An amorphous Nd:Gd3Ga5O12 thin film on yttrium aluminium garnet was used for demonstration of an infrared waveguide laser. A planar wave guiding structure was formed in deposited film between two parallel grooves micromachined using laser radiation delivered by a femtosecond CPA-Laser-System. The resulting waveguides were polished and provided with resonator mirrors. With a 5% output coupler at 1064 nm, a laser threshold of 1080 mW and 0.2% slope efficiency were obtained.