COMPARISON OF FORMATION PROCESS OF ULTRAVIOLET-INDUCED COLOR-CENTERS IN GEO2-SIO2 GLASS-FIBER PREFORM AND GE-IMPLANTED SIO2

Photochemical reactions induced by ultraviolet (UV) excimer lasers wer e investigated for a 10GeO(2)-90SiO(2) (mol%) glass fiber preform and a SiO2 glass implanted with Ge+ ions (1 x 10(16) cm(-2)) by the electr on spin resonance (ESR) and the optical absorption. Electron trapped c enters associated with fourfold coordinated Ge ion (GEC) were formed i n the former by irradiation with KrF laser (5 eV) or ArF (6.3 eV) lase r pulses. The concentration of GECs increased as the square of the las er power, which means that the formation reaction of GEC proceeds via a two-photon absorption process. Si E' centers (. Si=O-3, full width a t half maximum (FWHM) = 3 G) and peroxy radicals (PORs: Si-O-O . or O- 2(-)) were formed in the SiO2 glass implanted with Ge ions, which coul d be bleached by UV irradiation or prolonged isochronal annealing. The exposure of the annealed glass to excimer laser pulses induced Si E' centers having identical FWHM with that observed in the as-implanted g lass. No W-induced ESR signal related with Ge ion was confirmed before or after annealing. The intense UV absorption bands were induced both in fiber preform and implanted glasses, which should cause the positi ve index change.