The chief principle and properties of a novel noncascaded type optical bandpass filter with three unique general characteristics are presented. This device is based on a combination of a Michelson interferometer and a Gires-Tournois resonator (GTR). First, the filter has square-like frequency response with zero ripple, wide flat-top (0.74 bandwidth), unity contrast, sharp steepness, and infinite rejection ratio when GTR front surface mirror reflectance \rho is equal to one-third. Second, this filter possesses variable bandwidth and center-wavelength tunability features with simple control mechanism and nanosecond temporal response potential. Third, the desired features of the filter can be synthesized easily by mere inspection since only three parameters are required, and their expressions are given in simple analytic forms. Numerical results showing these features are presented and other characteristics are briefly discussed.
Benjamin B. Dingel and Tadashi Aruga, "Properties of a Novel Noncascaded Type, Easy-to-Design, Ripple-Free Optical Bandpass Filter," J. Lightwave Technol. 17, 1461- (1999)