Physicochemical Study of Rare Earth β-Diketonate Precursor for Optimizing MCVD-Vapor Phase Doping Technique

Abstract

Systematic investigation was performed to identify any physicochemical property change of rare earth (RE) β-diketonate precursor due to prolonged exposure to successive heating cycles. It is evident from the obtained results that the physical characteristics change rapidly in proportion to the thermal exposures which may lead to decomposition of the heated sample at much lower temperature than that of fresh sample. The observations further indicate, this RE chelate compound can be used satisfactorily as bulk precursor in vapor phase doping (VPD) process for up to five consecutive production cycles following which the sublimator needs to be refilled with fresh charge to maintain process reproducibility. It is also important to achieve the targeted specifications of laser/amplifier fiber preforms. According to our knowledge, this is the first ever study to identify any physicochemical behavioral change of RE precursor due to the thermal history as well as aging which would otherwise affect the performance of MCVD–VPD process.