Broadband amplifiers and tunable lasers in near-infrared region are indispensable to develop dense wavelength-division-multiplexing network systems. Recently, bismuth-doped glasses have been attracted much attention because of their near-infrared emission. However, optical characteristics of Bi-doped glasses have not been studied in detail. We have studied focusing on the control of emission bands of Bi-doped glasses as broadband gain media. The broad emission of more than 500 nm in full-bandwidth-half-maximum (FWHM) under 900 nm laser excitation was achieved in Bi-doped lithium-alumino-silicate (Bi-LAS) glasses. We have investigated the effect of host glass composition to an emission bandwidth of Bi-doped glasses. We have found out that the Bi-doped soda-lime-silicate glass realized the broadest emission of about 600 nm FWHM that is the broadest bandwidth ever reported as far as we know. In this report, we will present the characteristics of the Bi-doped soda-lime-silicate glass as ultra-broad near-infrared gain media. The Bi-doped soda-lime-silicate glasses were prepared by an ordinary melt-quenching method. The glasses were melted in a reduced atmosphere. The bulk glass samples were excited with a Ti: sapphire laser within a wavelength range from 700 to 920 nm in emission measurements. Emission from the samples was dispersed by a single monochromator and then detected by a near-infrared photomultiplier and an InGaAs PIN diode. A digital oscilloscope was used to obtain a decay curve of the emission.
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