Low loss WDM add drop node
AssigneeTransmode Holding AB
InventorsMagnus Oberg, Ulf Persson
Life of this patent
Estimating the term…
Abstract
In an optical fiber network bidirectional WDM traffic is sent on one optical main transmission fiber (1) between two nodes (A, B) connected in the path of the transmission fiber. The bidirectional traffic between a pair of nodes is carried on two different wavelength channels (Nos. 1, 2), one for each direction. The two wavelength channels are added to/dropped from the traffic in the ring fiber (1) in each node using a two-channel add/drop filter (5e1-2, 5w1-2), e.g. a band add/drop filter. In this way the number of add/drop filters connected in the path of the transmission fiber can be kept as small as possible.
Claims22
An optical add/drop node for bidirectional communication on a single fiber path in an optical WDM network, the optical add/drop node comprising:
- two main ports for connection in the single fiber path;
- a wavelength selective add/drop filter connected between the two main ports;
- an internal first drop filter connected to the wavelength selective add/drop filter and not connected in the single fiber path;
- at least one receiver connected to the internal first drop filter;
- and
- at least one source connected to the internal first drop filter,
- the add/drop filter branching or deflecting light, arriving at the optical add/drop node on one of the two main ports and having wavelengths of first WDM channels, to the internal first drop filter, the internal first drop filter connected to branch or deflect light to said at least one receiver and to receive light from said at least one source and let it pass to the wavelength selective add/drop filter to pass the wavelength selective add/drop filter to said one of the two main ports to be issued therefrom to the single fiber path when the node is connected in an optical WDM network.
An optical WDM network comprising a plurality of add/drop nodes connected by two or more parallel optical fiber paths, wherein bidirectional communication channels are arranged between pairs of the add/drop nodes over links, the bidirectional communication channel between each of the pairs of add/drop nodes being part of one of the two or more optical fiber paths and carried on two different WDM wavelength channels on a single fiber path, a different channel for each direction, each of the optical add/drop nodes comprising
- two main ports connected in the single fiber path;
- a wavelength selective add/drop filter connected between the two main ports;
- an internal first drop filter connected to the wavelength selective add/drop filter and not connected in the single fiber path;
- at least one receiver connected to the internal first drop filter;
- and
- at least one source connected to the internal first drop filter;
- the wavelength selective add/drop filter of each of the optical add/drop nodes branching or deflecting light, arriving at the optical add/drop node on one of the two main ports thereof and having wavelengths of first WDM channels, to the internal first drop filter of the optical add/drop node, the internal first drop filter connected to branch or deflect light to said at least one receiver of the optical add/drop node and to receive light from said at least one source of the optical add/drop node and let it pass to the wavelength selective add/drop filter of the optical add/drop node to pass the wavelength selective add/drop filter of the optical add/drop node to said one of the two main ports of the optical add/drop node to be issued therefrom to the single fiber path.
Dependencies are inferred from the claim text.