An optical fiber for use in making components of an optical communication system
has cladding and core materials the constituents of which cause a component made
from the fiber to have a rate of change with respect to temperature of a response
to a signal which passes through zero at a temperature Tm, where the
temperature Tm is at or near a selected temperature, or falls within
a selected temperature range; and the value of Tm of a fiber can be
controllably changed by changing the concentration of a selected constituent of
the fiber, such as, for example, the concentration of boron.
