| Abstract |
A high yield patterning technique for the fabrication of 1D relief Bragg reflectors and 2D photonic crystals is going to be demonstrated in the present study. The periodic structures were inscribed in Schott-USA IOG-1 Er/Yb-codoped phosphate glass substrates by employing multiple beam interference and the output of a high intensity pulsed 213nm Nd:YAG laser. The photosensitivity of the IOG-1 samples exposed to ultraviolet irradiation was studied and the nature of the induced damage in the volume of the material was investigated. Spectrophotometric data and diffraction efficiency measurements were employed in order to identify the irradiation induced absorption peaks and estimate the changes in the refractive index. In addition, Kramers-Kronig theoretical model and Urbach empirical rule were applied in order to enhance our understanding upon the defect formation mechanism and reveal possible changes in the structural order of the material. The relief patterns were formed by following a low-damage method, in which the glass samples were irradiated with laser energy densities below the ablation threshold. A 2-beam elliptical Talbot interferometer and a 4-beam interference setup were employed in order to inscribe 1D and 2D periodic structures, respectively, in the volume of the IOG-1 glass, in the form of a periodic perturbation in the optical and the structural properties of the material. The exposed areas were selectively removed by employing a wet chemical development technique. For characterizing and optimizing the chemical development process, acidic and alkaline solutions were tested of different molar concentrations. The resulting relief gratings were characterized in terms of diffraction efficiency, while atomic force and scanning electron microscopy were employed to investigate the topography of the relief structures. 2D and 1D periodic Bragg structures in rare earth doped phosphate glasses may constitute a nutritious starting base for the realization of high gain lasers or amplification devices with low pumping needs, which can find several applications in telecommunications or optical sensing domains.
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Fabrication of 1D and 2D relief Bragg reflectors in rare earth doped phosphate glass by employing holographic laser included structural modification
