Patent ID: 7679755

Claim:
An optical filter comprising a Michelson interferometer or a Mach-Zehnder interferometer having a first optical path length L 1 and a second optical path length L 2 , the Michelson interferometer or the Mach-Zehnder interferometer further having a plurality of Gires-Tournois interferometers (“GTIs”) replacing a plurality of mirrors of the Michelson interferometer or the Mach-Zehnder interferometer, a first one of the plurality of GTIs having a first GTI physical spacing d 1 , a second one of the plurality of GTIs having a second GTI physical spacing d 2 , wherein an optical path difference Δ L=L 1 −L 2 =0, d 2 =(2 n GTI 1 −1)(λ target1 /4), and d 2 =(2 n GTI 2 −1)(λ target2 /4), wherein λ target1 is a target wavelength of the first one of the plurality of GTIs, n GTI 1 is an integer greater than zero, λ target2 is a target wavelength of the second one of the plurality of GTIs, n GTI 2 is an integer greater than zero, λ target1 is different from λ target2 , and n GTI 1 is the same as n GTI 2 .