Cured compositions transparent to ultraviolet radiation

A coated optical fiber comprising:

• an optical fiber;
• and
• a curable coating composition comprising:
• an organohydrogenpolysiloxane;
• an alkenyl functional polysiloxane;
• and
• an ultraviolet radiation absorbing hydrosilation photocatalyst in an amount of from about 0.0003 wt % to about 0.15 wt % for crosslink formation between said organohydrogenpolysiloxane and said alkenyl functional polysiloxane, said curable coating composition crosslinking under the influence of ultraviolet radiation for providing a cured coating that allows from about 70% to about 99% of radiation of wavelengths from about 240 nm to about 275 nm to pass therethrough.

An optical fiber refractive index grating comprising:

• an optical fiber;
• a cured coating of a curable coating composition comprising:
• an organohydrogenpolysiloxane;
• an alkenyl functional polysiloxane;
• and
• an ultraviolet radiation absorbing hydrosilation photocatalyst in an amount of from about 0.0003 wt % to about 0.15 wt % for crosslink formation between said organohydrogenpolysiloxane and said alkenyl functional polysiloxane, said curable coating composition crosslinking under the influence of ultraviolet radiation for providing said cured coating that allows from about 70% to about 99% of radiation of wavelengths from about 240 nm to about 275 nm to pass therethrough;
• and
• a refractive index grating, formed in said optical fiber by high intensity ultraviolet radiation passing through said cured coating to produce periodic variations of refractive index in said optical fiber to provide said optical fiber refractive index grating.

A process for forming an optical fiber refractive index grating, said process comprising the steps of:

• providing an optical fiber;
• applying a curable coating composition to said optical fiber, said curable coating composition comprising:
• an organohydrogenpolysiloxane;
• an alkenyl functional polysiloxane;
• and
• an ultraviolet radiation absorbing hydrosilation photocatalyst in an amount of from about 0.0003 wt % to about 0.15 wt % for crosslink formation between said organohydrogenpolysiloxane and said alkenyl functional polysiloxane;
• exposing said curable coating composition to ultraviolet radiation for providing a cured coating that allows from about 70% to about 99% of radiation of wavelengths from about 240 nm to about 275 nm to pass therethrough;
• and
• exposing said optical fiber to a pattern of high intensity ultraviolet radiation passing through said cured coating to produce periodic variations of refractive index in said optical fiber to provide said optical fiber refractive index grating.

A process for continuous production of a coated optical fiber, said process comprising the steps of:

• providing a glass preform;
• heating said glass preform to a temperature to provide a melted portion of said glass perform;
• drawing an optical fiber from said melted portion of said glass perform;
• applying a curable coating composition to said optical fiber, said curable coating composition comprising:
• an organohydrogenpolysiloxane;
• an alkenyl functional polysiloxane;
• and
• an ultraviolet radiation absorbing hydrosilation photocatalyst in an amount of from about 0.0003 wt % to about 0.15 wt % for crosslink formation between said organohydrogenpolysiloxane and said alkenyl functional polysiloxane;
• exposing said curable coating composition to ultraviolet radiation for providing said coated optical fiber having a cured coating that allows from about 70% to about 99% of radiation of wavelengths from about 240 nm to about 275 nm to pass therethrough;
• and
• heating said coated optical fiber at temperatures between about 350° C. and about 700° C.