Abstract: An apparatus and method for cost-effectively conserving power in a PON. Protection ports, usually on a protection LT card, are configured to communicate with a selectable one of the downstream ODN splitter/combiners associated with the primary ports on the remaining LT cards of the OLT. Each protection port includes at least a splitter for distributing a transmitted signal from a light source to a plurality of switched protection fibers, and may have an optical amplifier to provide for lossless or low-loss distribution. Each port may also have a combiner for combining received signals from a plurality of switched protection fibers. Traffic flow through the OLT is monitored and when it is determined that traffic flow has reached a threshold level, traffic is routed via a protection port instead of a primary port. If the traffic rerouted to a protection card, then the method may further include powering down the primary LT card or placing it in a mode having reduced power consumption.

Abstract: An apparatus and method for cost-effectively providing protection in a PON. Protection ports, usually on a protection LT card, are configured to communicate with a selectable one of the downstream ODN splitter/combiners associated with the primary ports on the remaining LT cards of the OLT. Each protection port includes at least a splitter for distributing a transmitted signal from a light source to a plurality of switched protection fibers, and may have an optical amplifier to provide for lossless or low-loss distribution. Each port may also have a combiner for combining received signals from a plurality of switched protection fibers. When a failure is detected at a primary port, traffic is re-directed from the primary port to the protection port after the protection port has been configured to communicate with the same ODN splitter/combiner as the failed primary port.

Abstract: A point-to-multipoint protected network and related equipment for providing protection against fiber and/or interface failures while reducing or eliminating fiber redundancy requirements. The head end is coupled to a ring network comprised of one fiber via a passive splitter which sends the downstream signal out in both the clockwise and counterclockwise directions. Each network terminal is coupled to the ring through an optical circuit comprising a 1:2 optical switch and two passive optical taps. The terminal is coupled to the single terminal side of the 1:2 switch while the two terminals of the double terminal side of the switch are coupled to the ring in opposing directions, i.e., clockwise and counterclockwise, respectively. The two terminals of the double terminal side of the optical switch are each coupled to the ring via a passive optical tap. Other ring and star network embodiments are disclosed.

Abstract: A passive fiber optic tap for a single mode optical fiber is disclosed which utilizes cladding modes induced within the fiber by a microbender. The fiber has a symmetrically circular hour glass shaped notch for tapping radiation from the cladding mode and a detector converts light into an electrical signal. Large tapping ratios, low excess loss and structural compatibility with integrated circuity is obtained.

Abstract: An optical rotary joint has a first pair of light beam expanding graded index (GRIN) of refraction lenses coupled to ends of a first pair of lightguide fibers for coupling signals through the rotary joint interface in a first path which is coaxial with the axis of rotation in the interface. A second pair of lightguide fibers are coupled to a second pair of GRIN lenses off-axis and of much smaller diameter than the lenses of the first pair. Prisms couple signals between the off-axis lenses and a second path across the interface and which is also coaxial with the axis of rotation. Also shown is a method for compensating for lens irregularities.