| 摘要 |
An optical waveguide structure comprising an annealed phosphorous doped silicon dioxide core surrounded by silicon dioxide cladding layers on a silicon substrate. The refractive index of the core exceeds the refractive index of the cladding to enable waveguiding of optical signals in the core. The upper cladding layer, and in one embodiment also the lower cladding, comprises high boron and phosphorous doped silicon dioxide, suitably doped with greater than about 9% of boron and with about 2.5% to 3.5% phosphorous to obtain a thermal coefficient of expansion approximating that of the silicon substrate. In an alternative embodiment, the lower cladding layer comprises thermally grown silicon dioxide, preferably including an upstanding pedestal on which the waveguide core extends. Advantageously, the cladding composition enables substantially compensation of compressive stress in the core by residual tensile strain in the cladding, thereby reducing to very low values birefringence induced optical signal shift between TE and TM modes of propagation of an optical signal.
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