Patent ID: 7860359

Claim:
An optical device for splitting/combining a first and a second continuous optical wavelength bands, each wider than 10 nm, comprising: a first input port and a first and a second output ports; a first, a second, a third, a fourth and a fifth optical splitting devices optically coupled in cascade and optically connected to the first input port and to the first and second output ports, wherein: the first and the fifth optical splitting devices have an associated first coupling angle θ A ; the second and the fourth optical splitting devices have an associated second coupling angle θ B ; and the third optical splitting device has an associated third coupling angle θ C ; and a first, a second, a third and a fourth optical differential delay devices optically coupled to, and interleaved between, said optical splitting devices, wherein: the first, second, third and fourth optical differential delay devices have a respective differential delay, which is substantially an even multiple of π at least at a first wavelength (λ 1op ) within the first optical band and substantially an odd multiple of π at least at a second wavelength (λ 2op ) within the second optical band; the differential delay of the third optical differential delay device is opposite in sign with respect to the differential delay of the second optical differential delay; and the differential delay of the fourth optical differential delay device is opposite in sign with respect to the differential delay of the first optical differential delay, wherein: the coupling angles θ A , θ B and θ C being selected in order to direct more than half of an output power of a first optical radiation inputting at the first input port and having any wavelength within the first optical band to the first output port and more than half of an output power of a second optical radiation inputting at the first input port and having any wavelength within the second optical band to the second output port; and the coupling angles θ A , θ B and θ C satisfy, at least at a wavelength λ 3op within the first optical band, the following relation: 2θ A (λ 3op )+θ C (λ 3op )+2θ B (λ 3op )≦2π.