Characterization of defects in waveguides formed by electron irradiation of silica-on-silicon

Absorption spectroscopy and electron spin resonance are used to characteriz e optical waveguides formed by electron irradiation of plasma-enhanced chem ical vapor deposition (PECVD) silica-on-silicon. Nonbridging oxygen hole ce nters and E'(gamma) defect centers are positively identified in undoped fil ms. Evidence for peroxy radical and phosphorus oxygen hole centers is also found in phosphorus-doped samples. This is the first time that defects have been unambiguously identified in such guides; The charge-dose dependence o f the E' center density follows a saturating exponential curve well correla ted with refractive index changes previously reported, implying that a sing le first order process is responsible for both effects.