Patent ID: 7190856

Claim:
An optical apparatus, comprising: a first group of multiple diffractive element sets formed in or on a slab waveguide; a second group of multiple diffractive element sets formed in or on a slab waveguide; and a group of multiple channel waveguides, each channel waveguide of the group being arranged for routing an optical signal between a corresponding diffractive element set of the first group and a corresponding diffractive element set of the second group, each channel waveguide of the group including corresponding means for back-reflecting an optical signal propagating along the waveguide, each back-reflecting means being switchable between a transmitting operational state and a reflecting operational state independently of operational states of the other back-reflecting means, wherein: each diffractive element set of the first group is arranged so as to route an optical signal within a corresponding wavelength band between a first optical port and the corresponding channel waveguide, and each diffractive element set of the second group is arranged so as to route the optical signal within the corresponding wavelength band between a second optical port and the corresponding channel waveguide; and each diffractive element set of the first group, the corresponding channel waveguide, and the corresponding diffractive element set of the second group are arranged so as to route an optical signal entering through the first optical port within the corresponding wavelength band to the corresponding channel waveguide, transmit through the corresponding channel waveguide the optical signal thus routed if the corresponding back-reflecting means is in the transmitting operational state, and route the optical signal thus transmitted to exit through the second optical port, and wherein: each diffractive element set of the first group and the corresponding channel waveguide are arranged so as to route an optical signal entering through the first optical port within the corresponding wavelength band to the corresponding channel waveguide, back-reflect within the corresponding channel waveguide the optical signal thus routed if the corresponding back-reflecting means is in the reflecting operational state, and route the optical signal thus back-reflected to exit through the first optical port; or each diffractive element set of the second group and the corresponding channel waveguide are arranged so as to route an optical signal entering through the second optical port within the corresponding wavelength band to the corresponding channel waveguide, back-reflect within the corresponding channel waveguide the optical signal thus routed if the corresponding back-reflecting means is in the reflecting operational state, and route the optical signal thus back-reflected to exit through the second optical port.