Half-Coupler Active Optical Polymer Fiber-Optic Tunable Filter

Intelligent Fiber Optic Systems (IFOS) proposes a new approach for development of a compact, in-line, fiber-optic filter with low-voltage, ultra-high-speed tunability for active demodulation of wavelength division multiplexed (WDM) communications and dense computing systems as well as optical spectral sampling. The integrated structure is based on novel combination of three simply implemented potentially low-cost technologies: (i) Fiber Bragg Gratings (FBGs) produced by rapid laser writing, (ii) side-polished fibers or Fiber Half-Couplers (FHCs), and (iii) Active Optical Polymer (AOP) overlays. The FHC/AOP combination forms an asymmetric coupler whose transmission can be made particularly wavelength selective via judicious parameter choice. This feature is enhanced by FBGs. Both wavelength and coupling strength are tunable via AOP nonlinearity. Phase I objectives are: (i) to make use of IFOS's extensive light guide modeling and analysis capabilities to design an electro-optically tunable fiber-optic filter to satisfy the requirements and predict its performance, (ii) to implement a feasibility prototype demonstrating the effect of parameter choice on wavelength response and tunability, and (iii) to characterize its behavior (tuning range/speed, resolution, insertion loss). The proposed innovative high-speed tunable optical filter has the potential for low cost manufacturability, low power requirements and compactness. As well as in DOD's communications and computing programs, it can be used in commercial advanced WDM communications and sensor systems, intelligent fiber systems and spectroscopy.