Sachiyo Fukaya

The growth of Cr4+:YAG and Cr4+:GGG thin films by pulsed laser deposition

Abstract The Cr,Ca:Y3Al5O12 (YAG) epitaxial thin films on YAG substrate have been fabricated by pulsed laser deposition (PLD) method. The chemical shifts of chromium ions in the Cr,Ca:YAG thin films is measured by X-ray photoelectron spectroscopy as a function of oxygen partial pressure in the PLD chamber. By measuring the fluorescence intensity of Cr4+ ions in Cr doped YAG thin films, it is found that the addition of Ca2+ ions as a charge compensator under oxygen background pressure increases the active Cr4+ ion fraction in the YAG thin film. The oxygen partial pressure of 2 mTorr is found optimum to maximize the Cr4+ number density in the Cr,Ca:YAG thin film. The Cr,Ca:GGG epitaxial thin film also shows the dependence of Cr4+ fluorescence on the oxygen partial pressure during deposition.

Planar laser and nonlinear optical waveguides fabricated by pulsed laser deposition

Using KrF laser ablation the fabrication of Yb:YAG, and Cr:YAG planar waveguides as well as nonlinear Co:BaTiO3 waveguide has been carried out. The waveguide structure was fabricated by deposition of a rare-earth-doped YAG layer on an undoped substrate. The optical waveguide was characterized by optical absorption spectra, photoluminescence spectral intensity, optical propagation loss, and valence state by XPS. Co:BaTiO3 nonlinear optical, thin films have been fabricated with good quality using a new hybrid process of two-target pulsed laser deposition and in-situ pulsed laser annealing. Epitaxial Co:BaTiO3 films with Co/Ti concentrations of up to 5% were achieved by this method. Particles on the growing film were almost eliminated by in-situ laser annealing. Cobalt dopant concentrations were easily adjusted and controlled.

Fabrication of Nd:Gd3Ga5O12 and self Q-switched Nd,Cr:Gd3Ga5O12 laser waveguides by pulsed laser deposition method

In this paper, we report the fabrication of a neodymium-doped Gd3Ga5O12 (Nd:GGG) film and neodymium, chromiumcodoped Gd3Ga5O12 (Nd,Cr:GGG) film to realize a self Q-switched laser grown upon Y3A15O12 (YAG) substrate by pulsed laser deposition (PLD) method. Consequently, epitaxial films have been grown.

Fabrication of Nd, Cr co-doped GGG thin films for a Q-switched waveguide laser by the two-target pulsed KrF laser deposition method

The Nd3+,Cr4+ co-doped GGG epitaxial thin films for self Q-switched waveguide laser has been fabricated by a two-target pulsed laser deposition method. Concentrations of Nd and Cr ion in Nd,Cr:GGG thin films are well adjusted by changing laser ablation fluences independently for Nd:GGG and Cr,Ca:GGG sintered targets. The structure of Nd,Cr:GGG thin films on YAG substrate shows a planar waveguide structure. It is confirmed that Nd3+ and Cr4+ ions are optically active as laser active ions and saturable absorbers around 1.06 micrometers .

Fabrication of Nd,Cr codoped GGG waveguide structure by nanosecond KrF laser deposition

The Nd3+, Cr4+ co-doped GGG epitaxial thin films for self Q-switched waveguide laser has been fabricated by a two-target pulsed laser deposition (PLD) method. The concentrations of Nd and Cr ion in the co-doped GGG thin films are well controlled by changing respective KrF laser ablation fluence and repetition rate for Nd:GGG and Cr,Ca:GGG sintered targets. The structure of Nd,Cr:GGG thin films on YAG substrate shows a planar waveguide structure with high numerical aperture. It is confirmed that Nd3+ and Cr4+ ions are optically active as laser active ions and saturable absorbers respectively at 1.06 micrometer to be used for monolithic self-Q-switched waveguide laser to generate high peak power and short pulse output.

Epitaxial growth of 1 /spl mu/m thick nonlinear optical KNbO/sub 3/ thin films by pulsed laser deposition with in situ laser annealing

We fabricated a KNbO/sub 3/ [110] thin film on MgO [100] using pulsed laser deposition with in situ laser annealing. We used a KrF laser beam (248 nm, 20 Hz, 10 ns) that is divided into two beams: an ablation beam and an in situ laser annealing beam onto the film surface.

Nd, Cr co-doped gadolinium gallium garnet laser waveguide structure formed by pulsed laser deposition

Self-Q-switched Nd lasers with Cr-doped garnet as a saturable absorber have been reported. Recently, self-Q-switching operation of Nd,Cr co-doped YAG bulk crystal, which has both functions of a gain medium and a saturable absorber, has been demonstrated by diode pumping. This is a monolithic Q-switched bulk laser. This advantage is applicable to a waveguide laser which has merits of optical confinement, low oscillation threshold, high slope efficiency and device integration capability. In this study, Nd,Cr co-doped gadolinium gallium garnet (GGG) waveguide structures have been fabricated by pulsed laser deposition (PLD) method. The concentrations of Nd and Cr in thin films were well controlled by changing the laser ablation fluence for Nd:GGG and Cr:GGG targets. And the formed films showed excellent characteristics of a gain medium and a saturable absorber.