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Compositions which vitrify by means of a conventional glass melting method, containing a large amount of erbium ion were investigated in aluminosilicate, phosphate, borate, borosilicate, telluride and fluoride systems. As a result of melting test, we obtain some glasses which contain higher than 20 mol% erbium. In transparent materials containing erbium an anomalous optical absorption phenomena have been reported by Maeda et al. With increasing in an incident laser light intensity, the transmitted one through the transparency such as the glass decreases, that is called negative nonlinear absorption (NNA) effect. With a particular modulation degree of an incident laser light, the transmitted waveform were reversed in phase to an incident one. The NNA effect in these glasses was observed over a wide band of the wavelength, while in erbium doped yttrium aluminum garnet and erbium doped lutetium aluminum garnet crystals were observed at a narrow band. The discrepancy of the NNA effect between the glasses and the crystals might be explained in the term of absorption spectrum associated with erbium. Namely, the absorption spectra of erbium doped yttrium aluminum garnet crystal have a narrow absorption band of 788 nm, while that of the glasses have broad absorption band of about 800 nm.
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