Microphotonic Wideband Tapped Optical Delay Line FIR Filter Noise Analysis
John Wiley & Sons Inc
Computing, Health and Science
Electron Science Research Institute
MicroPhotonic broadband RF signal processors utilize true-time-delay methods to perform processing functions that cannot be achieved by conventional electronic methods. Using a tapped optical-delay line, a low-cost adaptive wideband FIR filter can be realized. We analyse the sources of noise for such a filter using commercially available VCSEL sources, PIN diodes, and transimpedance amplifiers. The power at each tap can be equal by using a suitably graded coating, or if the reflectivity is constant, there is an optimum reflectivity that maximizes the signal-to-noise ratio for a given number of taps, as we show in this paper.