Novel solutions to the synthesis problem of optical delay line filters: theory and experimental results

In this paper, we present new design methods to solve the synthesis problem for these optical delay line filters. These are presented both for conventional fiber-optic filters where all the filter coefficients are positive as well as for a new class of filters which incorporate negative coefficients by means of a differential photo-detection scheme. The latter allow the realization of highpass and bandpass transfer functions. Theoretical and experimental results are presented for these methods showing the potential of obtaining almost any desired transfer function