A waveguide and resonator are formed on a lower cladding of a thermo optic device,
each having a formation height that is substantially equal. Thereafter, the formation
height of the waveguide is attenuated. In this manner, the aspect ratio as between
the waveguide and resonator in an area where the waveguide and resonator front
or face one another decreases (in comparison to the prior art) thereby restoring
the synchronicity between the waveguide and the grating and allowing higher bandwidth
configurations to be used. The waveguide attenuation is achieved by photomasking
and etching the waveguide after the resonator and waveguide are formed. In one
embodiment the photomasking and etching is performed after deposition of the upper
cladding. In another, it is performed before the deposition. Thermo optic devices,
thermo optic packages and fiber optic systems having these waveguides are also taught.