The objective of this program was to assess and identify irradiation techniques which could be used to modify the optical charactistics of doped fused silica. Primary emphasis was placed on determining if gamma ray or neutron bombardment of the glass would enhance certain Raman and nonlinear optical effects. In particular, the effect of irradiation on optical two photon induced fluorescence was studied in detail. The maximum radiation exposures used were 10/sup 6/ rads (Si) of gamma rays and neutron fluences of 1 x 10/sup 14/ neutrons/cm/sup 2/. The optical measurements were made at room temperature between one and four months after irradiation. The maximum input light intensity was 10/sup 9/ watts/cm/sup 2/ at a near infrared (1.06 ..mu..) input wavelength which was chosen to lie in a transparent spectral region of the glass. Under these experimental conditions a careful search revealed no detectable two-photon induced fluorescence in the region from 550 to 900 nm. The upper limit for the photon efficiency of this process was determined to be less than 1 x 10/sup -10/%. 89 refs., 12 figs.