Abstract: A technique for processing dense wavelength division multiplexed optical signals in a network node is disclosed. In one embodiment, the technique is realized as an optical power managed network node comprising a dense wavelength division multiplexing device for combining a plurality of narrowband optical signals into a multiplexed polychromatic optical signal. The optical power managed network node also comprises a wavelength-selective optical power detector for detecting the power of each of the plurality of narrowband optical signals combined into the multiplexed polychromatic optical signal. The optical power managed network node further comprises a plurality of attenuators for attenuating the power of at least one of the plurality of narrowband optical signals based upon the detected power of each of the plurality of narrowband optical signals.

Abstract: A technique for processing dense wavelength division multiplexed optical signals in a network node is disclosed. In one embodiment, the technique is realized as an optical power managed network node comprising a dense wavelength division multiplexing device for combining a plurality of narrowband optical signals into a multiplexed polychromatic optical signal. The optical power managed network node also comprises a wavelength-selective optical power detector for detecting the power of each of the plurality of narrowband optical signals combined into the multiplexed polychromatic optical signal. The optical power managed network node further comprises a plurality of attenuators for attenuating the power of at least one of the plurality of narrowband optical signals based upon the detected power of each of the plurality of narrowband optical signals.

Abstract: An isolator assembly eliminates optical feedback or return beams in multiple stages. The isolator assembly employs passive optical components, including birefringent walk-off plates and non-reciprocal rotation plates. The rotation plates are located adjacent the walk-off plates. The optical components form a compact, integral unit. In the forward direction, the isolator assembly translates a polarized component beam through a triangular path to first separate and then combine the beam with respect to an orthogonally polarized component beam. By alternating birefringent sheets and rotation sheets, several isolator assemblies may be produced from a single layered stack.

Abstract: An optical coupler is disclosed which utilizes a pair of polarization selective filters to multiplex a message signal (of perhaps random polarization) with a pair of polarized pump signals onto a common signal path. The filters may be disposed within optical elements (e.g., cubes) which may be physically joined together to form a bulk optic device. An optical isolator may then be directly attached to the output of the bulk polarization independent optical coupler. The positioning of the pump signal inputs with respect to the filters provides either a co-propagating scheme or counter-propagating scheme.

Abstract: An optical isolator comprises a non-reciprocal rotator disposed between a pair of birefringent wedges, an input wedge and an output wedge. In order to reduce walk-off between the ordinary and extraordinary rays at the output of the isolator in one embodiment, the input signal is made incident on the input wedge at an angle above the normal to the wedge. At a particular angle related to various parameters of the isolator the relative walk-off can be reduced to essentially zero. In another embodiment, the input angle and various isolator parameters are mutually adapted so that the ordinary and extraordinary rays intersect within the isolator.

Abstract: A novel expanded beam coupling arrangement for use in association with single mode fibers is disclosed. An appropriate length of multimode fiber is fused to the endface of an input single mode fiber, where the length of the multimode fiber is chosen to provide the desired lensing conditions of the input beam. The multimode fiber is thus used as a lens, but provides many advantages over prior art optical connectors which use conventional quarter-pitch GRIN lenses epoxied to the fiber endfaces. In particular, the misalignment associated with the epoxied arrangement is reduced since the multimode fiber-lens connector of the present invention may be chosen to comprise the same outer diameter as the single mode fiber. Additionally, the use of a section of optical fiber as a lens allows for a fused connection to be used instead of an epoxied connection, which results in a more stable and rugged interface between the fiber and the lens.

Abstract: The present invention relates to a fused-fiber optical coupler, and method of forming the same, which does not require a tapering of the fibers. A two-step fusion process is utilized where initially the end sections of the plurality (N) of output fibers are fused together to create a bullet-shaped end section. The bullet-shaped end section is then butt-coupled and fused to the input fiber (or M input fibers) to form a 1.times.N (or M.times.N) fiber coupler.

Abstract: A polarization independent optical circulator is disclosed. A first birefringent plate (10) is used to separate an incident beam from a first port into two beams having orthogonal polarizations, and a second plate (11) recombines the beams at a second port. Means (12) providing nonreciprocal rotation of the polarizations are disposed between the plates. Placed between the rotating means and the second plate is a third plate (16) to further separate the beams and a reflecting element (17) for deflecting the beams toward the second port. The reflecting element includes a slotted portion (18) so that light from a third port can pass therethrough back toward the first port.