Tailoring of Raman gain bandwidth of tellurite glasses for designing gain-flattened fiber Raman amplifiers

The issue of widening the Raman spectral bandwidth of tellurite glasses while maintaining higher scattering intensity is addressed. Raman spectral bandwidths of tellurite glasses are widened by using a single Raman active component of suitable concentration in appropriate base glasses. It was observed that the MoO6 octahedra, due to their high octahedral distortion, have high Raman polarizability compared to WO6, NbO6, and TaO6 octahedra and PO4 tetrahedra. This high Raman polarizability enabled broadening of the spectral width up to similar to 350 cm(-1) while maintaining high Raman scattering intensities. Although similar bandwidths could be achieved using the combined generation of WO6 Octahedra and PO4 tetrahedra, the resultant Raman scattering intensity of such glasses is only half of that, which could be achievable using MoO6. It is shown that the simplest tellurite glass showing wide spectral broadening is a quaternary system comprising a network modifier (BaO or Bi2O3) and two Raman oscillators (NbO6 and MoO6 octahedra). (C) 2008 Optical Society of America.