| 摘要 |
The invention is directed to optical devices and techniques for sensing properties of an environment with improved stability and lower cost. In a disclosed embodiment of the invention, the method for sensing a property of an environment includes the steps of providing an optical waveguide in the environment and injecting a light beam into the waveguide such that at least two modes of the beam propagate in the waveguide, the effective index of refraction for the modes of the beam being affected by the property to be sensed. A further step of the invention includes generating an electrical signal representative of the interfering product of the at least two modes of the beam which have propagated through the waveguide. The signal is indicative of the property of the environment. In a disclosed embodiment of the apparatus of the invention, there is provided a substrate having an index of refraction ns. A waveguide layer is provided and has a surface adjacent the substrate, the waveguide layer having an index of refraction nf that is greater than ns. A superstrate is provided adjacent the opposing surface of the waveguide layer, the superstrate having an index of refraction nc that is less than nf, the index of refraction of the superstrate being affected by the environment. Means are provided for injecting an optical beam into the waveguide layer such that at least two modes of the beam propagate in the waveguide layer. Means are also provided for detecting the interfering product of said at least two modes of the beam which have propagated through the waveguide layer.
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