Aligned Narrowband Optical Filters having Flat Passbands and Comprising Offset Cascaded Broadband Optical Filters

摘要

A cascaded pair of broad bandwidth optical filters provides an overlap in pass-bands that forms a flat, narrow band optical filter. A first band-pass filter is operable to receive the optical signal and to transmit a first portion of the optical signal. The second band-pass filter receives the first portion of the optical signal transmits a second portion of the optical signal. The first band-pass filter has a first corner-pass wavelength of λ_a, a first corner-stop wavelength of λ_b, and a first pass-band center wavelength λ_pb1 such that λ_a≦λ_pb1≦λ_b. The second band-pass filter has a second corner-pass wavelength of λ_c, a second corner-stop wavelength of λ_d, and a second pass-band center wavelength λ_pb2 such that λ_c≦λ_pb2≦λ_d, wherein λ_aλ_cλ_bλ_d. As such, the combined pass-band is λ_c≦λ_pb3≦λ_b.