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We have proposed a silica-polymer hybrid variable optical attenuator that we made by creating two trenches along the core of a straight silica planar waveguide and filling the trenches with a polymer. The polymer, which had a superhigh thermo-optic coefficient, was specially designed and developed in this study to lower the power consumption of the device. We achieved a maximum attenuation of -29 dB for the device by changing the polymer's temperature by only 7 [degrees]C. The device has a very low power consumption at 2-3 mW/channel, making it a good candidate for integration with arrayed waveguide gratings.

Volume relaxation in polymers and the effect intrinsic to glassy polymers can significantly affect their refractive index over time. Its [beta] rate has been found to be related only to relaxation temperature T and the glass transition temperature of the polymer [T.sub.g] and not to the polymeric chemical structure. Universal values of [beta] have been obtained for polymers and were used to predict the minimum index change related to volume in polymers. The index change is in the range from 7.86 x [10.sup.-5] to 5.26 x [10.sup.-4] when the [T.sub.g] - T value of polymers is between 90 and 350 [degrees]C. These volume-relaxation-induced changes can cause serious deterioration or even failure in corresponding polymer waveguide devices, such as arrayed waveguide gratings and variable optical attenuators, when the [T.sub.g] of a polymer is not sufficiently high. A minimum requirement is therefore suggested for the [T.sub.g] of polymers used to fabricate waveguide devices. OCIS codes: 230.7390, 160.5470, 250.5300, 130.3120, 130.3130.

We propose and demonstrate a novel high-voltage optical-fiber sensor. This sensor consists of an emitting fiber, a receiving fiber, and a piezoelectric bimorph transducer. The emitting fiber is fixed in a base, whereas the receiving fiber is mounted on the free end of the piezoelectric bimorph transducer. When a voltage is applied to the piezoelectric bimorph transducer, its free end is displaced over a distance [delta] The displacement induces a loss in the optical coupling between the emitting and the receiving fiber. The voltage can be measured by monitoring the coupling loss. OCIS code: 060.2370.