Reconfigurable Solid State Weighted Tapped Delay Line Filter

Optical circuits provide many benefits for large time-bandwidth signal processing in microwave photonic applications. SeTapped delay lines using surface acoustic waves (SAWs) are in use today for carrier frequencies in the MHz to 100 MHz range, and thus their general theory and efficacy are well known. In order to be widely applicable, the tapped delay line filter must be robust enough to be deployed in fixed as well as mobile platforms. This calls for a solid state implementation of the components and a high degree of integration of all the optical elements. Further, it is desirable to have rapid real time reconfigurability and feedback for frequency scanning, filter shape adaptation, and noise figure optimization. Finally, an integrated solid state approach that uses conventional semiconductor practices will ensure cost effectiveness, scalability, and multiple sourcing. We propose through our Little Optics Division to implement reconfigurable optical tapped delay line filters using our proprietary high-index contrast planar lightwave circuit technology, achieving robust solid state filter solutions with femtosecond accuracy on the delay elements. Georgia Tech Research Institute (GTRI) will develop adaptive algorithms for the control of the filter and facilitate system testing of the filter units.