OPTICAL PROTECTION SWITCH EMPLOYING AN INTERFERENCE FILTER

• Main Authors: FISHMAN, DANIEL A, FANG, WEIIAO WILLIAM, DENKIN, NATHAN MYRON
• Format: Patent
• Language: English; French
• Published: 19.06.1999
• Edition: 6
• Subjects: DEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH ISMODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THEDEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY,COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g.SWITCHING, GATING, MODULATING OR DEMODULATING; ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; FREQUENCY-CHANGING; MULTIPLEX COMMUNICATION; NON-LINEAR OPTICS; OPTICAL ANALOGUE/DIGITAL CONVERTERS; OPTICAL LOGIC ELEMENTS; OPTICS; PHYSICS; SELECTING; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF; TELEPHONIC COMMUNICATION; TRANSMISSION; TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHICCOMMUNICATION

A protection facility is provided for use in an optical communications node that communicates with another optical communications node via first and second bi-directional communications paths respectively serving as a service path and protection path, in which a filter filters signals respectively received over the service and protection paths and generates a main signal and a complementary signal for each of the paths. A control unit then generates a Loss of Signal (LOS_A) indication for the service path if a SUM signal or DIFF signal respectively derived as a function of a sum of the main and complementary signals generated for the service path and difference between the main and complementary signals generated for the service path is less than a respective threshold value. A switch then invokes protection switching responsive to the presence of the LOS_A indication.