Tunable high-resolution fiber optic WDMs using the high-index approach

High resolution (1 nm), low loss (< 0.2 dB) optical fiber WDMs based on evanescent field coupling between a single mode fiber, side polished close to the core, and a planar high index overlay have been reported previously. By using electro-optic materials in the role of either the overlay or superstrate (above the overlay) the wavelength characteristics may be dynamically tuned under operational conditions. Here we report the results of a theoretical and experimental investigation of the performance limits of these devices. Specific aspects dealt with include the practical limits on the optimization of resolution and tunability (active and passive). Material investigations for use in the overlay structure include lithium niobate, liquid crystals, zinc selenide (vacuum deposited), and silicon. It is concluded that sub nanometer resolution and tuning ranges of several tons of nanometers are realistic for these systems.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.