US 8,078,052 B2Granted

Protocol-less all-optical 1+1 bidirectional revertive linear protection system

AssigneeCisco Technology, Inc.

InventorsAldo Aprile, Valerio Viscardi

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Abstract

In an optical network a 1+1 bidirectional protection system is presented. Each node across a link has photodiodes to monitor the power of signals received by the node on receiving working and protection optical fibers and also optical switches connected to transmission working and protection optical fibers to modulate signals to its counterpart node across the link. When a node detects a fault in the receiving working optical fiber, not only does the node switch to the receiving protection optical fiber, but it also switches to the transmission protection optical fiber to signal the fault to the node across the link. The optical switches on transmission working and protection optical fibers allow the two nodes across the link to signal each other at a protocol-less or primary protocol level for the link to revert back to its initial state.

Claims18

Dependent claims

In an optical network having a link carrying optical signals in one direction and carrying optical signals in an opposite direction with 1 +1 protection in each direction, each node for said link comprising:

an optical splitter having an input terminal configured to receive optical signals to transmit across said link, a first output terminal and a second output terminal;
a first optical modulator connected between said first optical splitter output terminal and a first terminal for connection to a first transmission optical fiber configured to carry said optical signals across said link in said one direction;
a second optical modulator connected between said second optical splitter output terminal and a second terminal for connection to a second transmission optical fiber configured to carry said optical signals across said link in said one direction;
a receiving optical switch having an output terminal for transmitting optical signals, a first input terminal for receiving said optical signals from a first receiving optical fiber for carrying across said link in said opposite direction, and a second input terminal configured to receive said optical signals from a second receiving optical fiber across said link in said opposite direction;
a first photo diode coupled to said first input terminal of said receiving optical switch;
and
a second photo diode coupled to said second input terminal of said receiving optical switch;
wherein said first and second optical modulators are configured to continuously toggle between an optical signal and a partially attenuated optical signal for transmission across said first and second transmission optical fibers.

5 more elements

Dependencies are inferred from the claim text.