Abstract: The present invention is directed to an optical time-domain reflectometer which employs a so-called “out-of-band” offsetting to cancel the effects of Raman non-linearities which extract energy from the traffic signal wavelengths and amplify the test signal back-scattering. Losses and faults in the optical fibers are monitored by measuring the back-scattered portion of the light launched into the fiber, with the test signal back-scattering judiciously offset to account for the Raman non-linearities. That is, the effects of the Raman non-linearities are taken as a baseline measurement and, then accordingly used as a basis to offset the test signal back-scattering.

Abstract: The present invention is an optical spectrum analyzer (OSA) comprising a tree-structure of N-stage wavelength filters or “wavelength slicer” which “slice” the incident optical signal into desired groupings of individual sliced spectral components, each along a different output optical fiber. Cascaded fiber Bragg gratings and delay lines coupled to each output optical fiber then uniquely map the “sliced” spectral components into the time domain such that each spectral component is allocated a unique time slot.

Abstract: In accordance with the teachings of the present invention, it has been discovered that an optical analysis that is uniquely based on geometrical rather than diffraction considerations, for the purposes of controlling the size of the region from which the photoluminescence is collected, provides an optical system capable of performing photoluminescence microscopy and/or spectroscopy without the disadvantages of the prior art. It is based, in part, on the use of an optical fiber(s) as a field stop within the detection arm(s) of the optical system for coupling the photoluminescence into an optical spectrum analyzer (OSA) and/or photodetector, wherein the diameter and the numerical aperture of the optical fiber are judiciously chosen to limit the field of view, or the region from which the photoluminescence is collected.

Abstract: The present invention employs “polarization markers” deployed immediately after the branching portion of a passive optical network (PON) for measuring and monitoring transmission losses and faults. Each polarization marker is configured to produce a unique polarization dependent loss (PDL) within the corresponding branch of the PON. Since each polarization marker uniquely attenuates optical test pulse(s) launched into the PON, the back-scattering uniquely varies with the launched state of polarization. Losses within each branch of the PON are then monitored by measuring the back-scattered portion of the launched optical pulse(s) as a function of time for different known states of polarization, wherein the unique PDL associated with each polarization marker is used as the basis for distinguishing the branches from one another.