The increase of absorption loss in photosensitivity enhanced optical f
iber via H-2 loading induced in the making process of fiber grating wa
s measured. From the results it can be seen that hydroxyl induced by e
xposing the H-2 loaded GeO2-doped optical fiber to 248 nm light causes
large absorption loss at 1.4 mu m. A reaction model is postulated to
describe the process that leads to the loss increase and photosensitiv
ity enhancement in GeO2-doped optical fiber.