Integrated optical transducer platforms for the measurement of small changes in the refractive index or thickness of a sensing layer are of considerable interest for the fabrication of a wide variety of sensors. Progress toward the development of two types of such platform is described. A replicated polymer platform fabricated by the embossing or molding of a surface relief microstructure followed by the evaporation of a dielectric waveguide layer forms the basis of a low-cost disposable device for applications such as medical diagnostics. A fully integrated, monolithic III-V platform with laser, interferometer, modulator, sensor pad, and detector is also being developed for compact, rugged sensors required in applications such as environmental sensing and process control. Both transducer platforms are suitable for many different types of sensors and can be extended to multichannel sensor structures for the simultaneous measurement of a number of analytes.