Patent ID: 7433054

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 spacing d 1 , a second one of the plurality of GTIs having a second GTI spacing d 2 , wherein a filter function H = sin 2 ⁡ ( ϕ 2 ) or H = cos 2 ⁡ ( ϕ 2 ) , a phase difference φ=φ arm 1 −φ arm 2 , ϕ arm ⁢ ⁢ 1 = 2 ⁢ ⁢ π ⁢ L 1 λ + ϕ GTI ⁢ ⁢ 1 , ϕ arm ⁢ ⁢ 2 = 2 ⁢ ⁢ π ⁢ L 2 λ + ϕ GTI ⁢ ⁢ 2 , ⁢ ϕ GTI ⁢ ⁢ 1 = 2 ⁢ ⁢ arctan ⁡ ( 1 - ρ 1 1 + ρ 1 ⁢ tan ⁡ ( 2 ⁢ ⁢ π ⁢ ⁢ d 1 λ ) ) , ⁢ ϕ GTI ⁢ ⁢ 2 = 2 ⁢ ⁢ arctan ⁡ ( 1 - ρ 2 1 + ρ 2 ⁢ tan ⁡ ( 2 ⁢ ⁢ π ⁢ ⁢ d 2 λ ) ) , λ is a wavelength of an input beam, ρ 1 is an amplitude reflectivity of a mirror of the first one of the plurality of GTIs, and ρ 2 is an amplitude reflectivity of a mirror of the second one of the plurality of GTIs, wherein an optical path difference Δ L=L 1 −L 2 =0, d 1 =(2 n GTI 1 −1)(λ target /4), and d 2 =0, wherein λ target is a target wavelength, and n GTI 1 is an integer greater than zero.