| 摘要 |
A device for adding and/or dropping a signal to a transmission line. First (34) and second (36) optical circulators are connected by at least one switchable grating (32), whereby a grating reflector may be switched into or out of the connecting path between the two circulators. A plurality of optical signals, each centered about a different wavelength, is coupled to a first port (1) of the first circulator; these signals appear at the second port (2) thereof. If a grating reflector capable of reflecting is switched into the circuit, the signal centered about propagates from the second port (2) of the first circulator (34) and reflects from the grating reflector back into the second port (2) and out of the third port (3). The remainder of the input signals that are not reflected by the grating reflectors propagate into the first port (1) and from the second circulator (36) as an output thereof. Also, a signal at wavelength input to the third port (3) of the second circulator (36) propagates from the first port (1) to the grating reflector where it reflects back to the second circulator (36) and appears at the second port (2) as an output thereof. |
