Abstract: A bidirectional digital communication circuit and a bidirectional digital communication method for combining multi-channel signals to a duplex digital communication system apply time division multiplexing. The signals can be unidirectional and bidirectional; signals relationship is not necessary. The direction detector circuit determines signal directional automatically to avoid the signal loop. It's suitable for applying to fiber, cable or wireless communication system which is needed to minimize the communication channels.

Abstract: A method and apparatus is provided for biasing an avalanche photodiodes (APD). The method includes developing a first output signal s(v1) from the APD when biased with a first bias voltage v1 and developing a second output signal s(v2) from the APD when biased with a second bias voltage v2, wherein s(v)=PRZM(v), (P) is an light power illuminating the APD, R is a responsivity of the APD, M(v) is an APD avalanche gain and Z is a trans-impedance amplifier gain (Z). The method continues by acquiring a ratio r=s(v1)/s(v2)=PRZM(v1)/[PRZM(v2)]=M(v1)/M(v2) and invoking a feedback control method to bias the APD using the ratio r.

Abstract: A method and apparatus is described to beam split or combine light for multiple fiber optic channels in a single device. Multiple light beams may enter the device through an array of fiber ports with each port having a collimating lens. The device includes a beamsplitter/combiner having a common optical aperture to simultaneously receive the light beams. The device may be used in laser amplification systems to combine lower power pump light beams into a single, higher power pump light beam.

Abstract: An optical device is provided which includes a slab waveguide and at least one input waveguide coupled to a first side of the slab waveguide. The device also includes a plurality of output waveguides coupled to a second side of the slab waveguide. The slab waveguide has a segmented transition region that includes a plurality of waveguiding regions spaced apart from one other by at least one discrete sector.

Abstract: A method and apparatus is provided for reformatting or interleaving a WDM signal that includes a plurality of optical channels having a first bandwidth and a first channel spacing. The method begins by receiving the WDM signal and dividing it into first and second subsets of optical channels each having a second channel spacing. Next, the first subset of optical channels are divided into third and fourth subsets of optical channels each having a third channel spacing. In addition, the second subset of optical channels is divided into fifth and sixth subsets of optical channels each having a fourth channel spacing. The third and fifth subsets of optical channels are combined to generate a first output WDM signal, while the fourth and sixth subsets of optical channels are combined to generate a second output WDM signal.

Abstract: Optical signal interleaver/deinterleavers with reduced chromatic dispersion are described. In one embodiment, the interleaver/deinterleavers include two optical filters and an optical isolator coupled to receive the output of each of the optical filters. The optical isolators feed the filtered signals back to the filters. Passing the filtered signals back through the filters in the opposite direction as the first pass allows the filters to cancel, or nearly cancel, the chromatic dispersion caused by the filters on the first pass. Thus, the interleaver/deinterleavers provide reduced chromatic dispersion as compared to use of a single filter or of cascaded filters.

Abstract: A filtering device such as an optical interleaver/deinterleaver includes first and second optical couplers each having two inputs and two outputs. The inputs of the first coupler are adapted to receive input optical signals to be filtered and the outputs of the second coupler are adapted to provide filtered output optical signals. A first optical waveguide optically couples a first output of the first coupler to a first input of the second coupler. A second optical waveguide optically couples a second output of the first coupler to a second input of the second coupler. The filtering device also includes an optical resonator and a third optical coupler optically coupling the optical resonator to the second optical waveguide.

Abstract: Optical signal interleaver/deinterleavers with reduced chromatic dispersion are described. In one embodiment, the interleaver/deinterleavers include two optical filters and an optical isolator coupled to receive the output of each of the optical filters. The optical isolators feed the filtered signals back to the filters. Passing the filtered signals back through the filters in the opposite direction as the first pass allows the filters to cancel, or nearly cancel, the chromatic dispersion caused by the filters on the first pass. Thus, the interleaver/deinterleavers provide reduced chromatic dispersion as compared to use of a single filter or of cascaded filters.

Abstract: The abstract is amended to read, “An inventive method and apparatus is provided by a bidirectional optical 1×2 device formed by a cascade of three optical 2×2 devices. Each 2×2 device is bidirectional where optical signals propagate through the 2×2 device in the forward and backward directions simultaneously. The demultiplexing and multiplexing occur simultaneously to thereby perform bidirectional 1×2 optical demultiplexing and 2×1 optical multiplexing in the 1×2 device.

Abstract: A cascaded interleaver includes at least three two-stage Fourier filters. A first of the Fourier filters includes first and second waveguides such that the first waveguide has a longer optical path length than the second waveguide. A second of the Fourier filters includes third and fourth waveguides such that the third waveguide has a longer optical path length than the fourth waveguide. A third of the Fourier filters has fifth and sixth waveguides such that the fifth waveguide has a longer optical path length than the sixth waveguide. The third waveguide has an input coupled to an output of the first waveguide and the fifth waveguide has an input coupled to an output of the second waveguide. At least one of the Fourier filters include at least three couplers alternating with a delay path between adjacent ones of the couplers. A second of the couplers is of an order different from a first and third of the couplers.

Abstract: A method is described that involves scanning a laser beam across and applying a stretching force to a fusion region that is formed by a neighboring pair of optical fibers that include a core and a cladding layer. The scanning and applying occurs while the optical permissiveness of an optical path that flows through the fusion region is monitored.

Abstract: A housing is provided for maintaining a planar lightguide circuit at a temperature within a predetermined temperature range independent of ambient temperature. The housing includes a planar heating arrangement supporting and in thermal contact with the planar lightguide circuit. Also included is a frame assembly having a first surface on which the planar heating arrangement is fixed. The frame assembly has at least one opening through which extends at least one optical fiber coupled to the planar lightguide circuit. An overmold, which is molded around the frame assembly, includes at least one strain relief member through which the optical fiber extends.

Abstract: A variably configurable and modular retainer for various discrete optical components (such as passive optical elements and mass fusion splices) is provided by a substantially planar base having an optical component support surface. Complementary finger pairs extend upwardly from the base. Each finger is disposed in an opposing arrangement with the other finger in the finger pair and is provided with an inner and outer surface. The respective opposing inner surfaces (each having a slightly concave profile) define an optical component receiving area that is sized and shaped to accommodate an optical component or splice. Each finger pair is resilient and laterally biased with a normal bias such that the inner surfaces are urged laterally inwardly and being movably outwardly for interlockingly engaging an optical component using snap-fit. The optical component may be thereby retained against the support surface of the base.

Abstract: A method and apparatus provides a WDM optical signal having a plurality of channels with a pair-wise orthogonal polarization state. The method begins by receiving a plurality of unpolarized optical wavelengths defining a plurality of optical channels separated by a prescribed channel spacing. A polarization wavelength dependent shift is imparted to the optical wavelengths, which is substantially equal to a particular fraction of the prescribed channel spacing.

Abstract: A method and apparatus is described for stripping the coating of an optical fiber. A fixture having a fiber cleat may be used to secure an optical fiber to enable removal of the protective coating from the fiber along a precise length of the fiber. The length of protective coating removal may be controlled by a strip guide. A stop coupled to the apparatus also controls how much of the coating is removed.

Abstract: Optical signal interleaver/deinterleavers with reduced chromatic dispersion are described. In one embodiment, the interleaver/deinterleavers include two optical filters and an optical isolator coupled to receive the output of each of the optical filters. The optical isolators feed the filtered signals back to the filters. Passing the filtered signals back through the filters in the opposite direction as the first pass allows the filters to cancel, or nearly cancel, the chromatic dispersion caused by the filters on the first pass. Thus, the interleaver/deinterleavers provide reduced chromatic dispersion as compared to use of a single filter or of cascaded filters.

Abstract: A system and method for twisting together two fibers to create an optical fiber coupler is disclosed. In one embodiment, the two optic fibers are threaded through a chuck, which is rotated by a motor to create an amount of twist in the two optical fibers necessary to cause a light signal transmitted through the twisted fibers to have a desired polarization state. A heater applies heat to the twisted fibers while rotating the chuck to create an optical fiber coupler.

Abstract: A variably configurable and modular retainer for various discrete optical components (such as passive optical elements and mass fusion splices) is provided by a substantially planar base having an optical component support surface. Complementary finger pairs extend upwardly from the base. Each finger is disposed in an opposing arrangement with the other finger in the finger pair and is provided with an inner and outer surface. The respective opposing inner surfaces (each having a slightly concave profile) define an optical component receiving area that is sized and shaped to accommodate an optical component or splice. Each finger pair is resilient and laterally biased with a normal bias such that the inner surfaces are urged laterally inwardly and being moveably outwardly for interlockingly engaging an optical component using snap-fit. The optical component may be thereby retained against the support surface of the base.

Abstract: A method and apparatus provides a WDM optical signal having a plurality of channels with a pair-wise orthogonal polarization state. The method begins by receiving a plurality of unpolarized optical wavelengths defining a plurality of optical channels separated by a prescribed channel spacing. A polarization wavelength dependent shift is imparted to the optical wavelengths, which is substantially equal to a particular fraction of the prescribed channel spacing.

Abstract: A structure and method are provided to improve stability of a multi-window dense wavelength division multiplexers and to provide polarization-independent multi-window dense wavelength division multiplexers. In one embodiment, the coupler region of a multi-window wavelength division multiplexer (MWDM) is hermetically sealed in a protective casing to prevent moisture from affecting the passband wavelength drifting in the coupler. In one embodiment, the coupler is elastically twisted at the fused fiber portion to reach polarization cancellation. In another embodiment, the coupling region of the coupler is exposed to UV-radiation for passband wavelength adjustment. In yet another embodiment, a passive thermal compensation technique is used to minimize the thermal effect on the passband wavelengths for dense WDM applications. In a further embodiment, the coupler is mounted on the substrate using soft adhesives in conjunction with rigid adhesives, to improve mechanical shock protection.