Direct laser writing of self-developed waveguides in benzyldimethylketal-doped sol-gel hybrid glass

Exposure of benzyldimethylketal (BDK)-doped sol-gel hybrid glass films to ultra-violet light produces a refractive index increase up to 43 × 10^-3 and an increase in thickness due to photolocking of the BDK into the sol-gel hybrid glass matrix. Thus, single mode ridge waveguides at λ = 1550 nm can be fabricated by direct laser exposure without using photomask and development processes. The slower laser writing speed gives greater refractive index change producing more circular guided mode profiles.