Abstract: An all-fiber, all-states of polarization linear design depolarizer is provided. It is made of two polarization combiners (PC1,PC2) with a 2×2 directional coupler (DC) between them. The connections between the coupler (DC) and the two polarization combiners (PC1,PC2) have optical phase delays (L1,L2) and half wave polarization rotators (PR1,PR2,PR3) to make proper adjustments.

Abstract: An optical coupler is provided. It has a bundle of multimode fibers with a few-mode fiber in its centre. Such bundle is fused at one end which is the output end for the signal that is transmitted by the few-mode fiber. To make the coupler, this output end of the bundle is aligned and spliced with a large area core double clad fiber while preserving the modal content of the feed-through. A method for making such optical coupler is also provided. It includes the steps of bundling a central few-mode fiber with a plurality of multimode fibers and then fusing one end of such bundle and aligning it and splicing with a large core double clad fiber, while preserving fundamental mode transmission from one to the other.

Abstract: An all-fiber broadband polarization combiner is disclosed based on a Mach-Zehnder (MZ) structure. The entry coupler to the MZ is a polarization pump combiner (PPC) and the exit coupler is a wavelength division multiplexer (WDM) coupler. The two couplers are interconnected with two standard SM fibers which form the arms of the central zone of the MZ. Two polarization maintaining (PM) fibers are spliced to the two input arms of the PPC and are oriented so that polarization X in one PM fiber is orthogonal to polarization Y in the other PM fiber. And the MZ is induced with a phase shift ?? of ? between the two arms of the central zone.

Abstract: A packaging device for protectively enclosing an optical component in a substantially clean and anhydrous environment without imparting undue mechanical stresses on the optical component and adjacent segments of optical fiber coupled thereto. An intermediate component is used in combination with a sealing material for sealing the fiber aperture of a protective housing while allowing an optical fiber to extend therethrough. The protective housing is made out of a material having a coefficient of thermal expansion that closely matches that of the optical fiber. A chain of material CTE that includes the CTE of the intermediate component is used in order to circumvent the need for a sealing material having a high melting temperature. The packaging device is also designed so as to reduce water ingress by optimizing the configuration of the sealing component and adjacent structures.

Abstract: A packaging structure for supporting a segment of optical fiber provided with a wavelength filter optically coupled thereto. The wavelength filter defines a temperature dependent center wavelength and a rate of wavelength drift per temperature change. The optical fiber is attachable about a fiber fast first attachment point and a fiber second attachment point to a housing having a generally hollow housing body for protecting the wavelength filter. The structure allows for both adjustment of the center wavelength and also for adjustment of the rate of wavelength drift per temperature change independently from the adjustment of the center wavelength. The wavelength excursion is typically adjusted by adjusting the spacing between the fiber first and second adjustment points. The center wavelength is typically independently adjusted by adjusting the tension imparted on the wavelength filter when the fiber is attached to the housing.

Abstract: This invention provides a method of obtaining accurate measurements of polarization dependent loss and insertion loss during the tests aiming at measuring the polarization properties of optical components. This is achieved by taking into account every polarization disturbance in the line between generation of known states of polarization and the device under test. The method involves computing within a desired range of wavelengths either the transfer matrix of each polarization perturbing element or of all polarization perturbing elements as a whole, and compensating for errors introduced by these polarization perturbing elements.

Abstract: The invention provides an all-fiber Mach-Zehnder interferometer in which the composition of one of the arms, which connect the couplers, or of a segment of such arm, is doped with dopants, such as GeO2, P2O5, B2O3 and F. The doping is adjusted to obtain a desired thermal dependence of the interferometer within a given temperature range. The segments can further be tapered with an adiabatic taper.

Abstract: An all-fiber Mach-Zehnder interferometer has a central fiber structure in which two single-mode fibers are placed to have a desired path difference and are stabilized in such position by bonding them in certain spots. A coupler is then made on each side of the central fiber structure to produce the Mach-Zehnder effect. The combination of the central fiber structure and of the couplers at each end is mounted on a substrate and packaged to produce the interferometer.

Abstract: An optical fiber filter (25) with a non-sinusoidal wavelength response is produced by forming an adiabatic taper in a single mode fiber (10) and forming non-adiabatic tapers (18, 20) on slopes at each end of the elongated central region of this adiabatic tape and in the middle of the central region (12). The non-adiabatic taper (22) in the middle of the central region (12) produces a phase shift in the wavelength response leading to non-sinusoidal filtering characteristics. The filter may be combined with a Mach-Zehnder interferometer to produce a Mach-Zehnder device with a non-sinusoidal wavelength response.

Abstract: A Mach-Zehnder device including an input port, an output port, a substantially achromatic first coupling region optically connected to the input port and a substantially achromatic second coupling region optically connected to the output port. An intermediate region is optically connected to the first and second coupling regions. The intermediate region includes a first intermediate branch and a second intermediate branch. The first intermediate branch defines a phase shifting portion. The phase shifting portion, in turn, defines a phase shifting portion level of birefringence over the length of the phase shifting portion. The phase shifting portion level of birefringence is different that the level of birefringence prevailing over the remainder of the first intermediate branch.

Abstract: Multiplexing and demultiplexing single-mode fiber optic couplers are fabricated by aligning two single-mode fibers which have been stripped of their protective plastic jackets and cleaned so that they are held in parallel contact with each other, and then fusing these fibers to achieve a desired fusion profile and elongating the fused fibers to achieve a match point between the wavelength period and the polarization phase. The elongation process is interrupted and resumed as required to obtain a precise match point required to produce the desired multiplexing or demultiplexing coupler.

Abstract: An all-fiber optical depolarizer is provided in which polarized light is controllably injected into a polarization beam splitter at a 45° angle. The beam splitter is combined with a loop made of standard non-birefringent fiber through which one of the polarizations split by the beam splitter circulates. The loop has a length greater than the coherence length of the light source. The interaction of the beam splitter and the loop produces incoherent depolarized light at the output transmission port of the beam splitter.

Abstract: An optical filter is produced that has a desired spectral response. This is done by first decomposing the desired spectral response into individual simulated responses (F1 . . . F4) using a suitable computer program. Then tapered fiber filters are manufactured with parameters that closely match the individual responses. And finally the tapered fiber filters are concatenated on a single-mode fiber to produce the optical filter with a total response that closely matches the desired spectral response.

Abstract: A temperature stabilized tapered fiber optic component is produced, such as a fiber optic coupler or a fiber optic filter. In the case of the component such as a coupler, at least two fibers are fused and tapered to achieve a desired taper profile with suitable mechanical and wavelength properties. In the case of a component such as a fiber filter, only one fiber is tapered. Once the component is formed, it is solidly secured to a rigid substrate that produces a mechanical stress such as to compensate for any modal phase shift of the component due to temperature variation. Also, the mechanical phase dependence of the component may be adjusted in relation to the substrate to provide the desired temperature compensating effect. Preferably, both these features are used to achieve the best possible temperature stabilization.

Abstract: An optical fiber winding tool for winding a strip of optical fiber. The optical fiber winding tool having a guiding body defining a guiding recess. A fiber inlet aperture extends into the guiding recess for allowing the slideable insertion of the strip of optical fiber thereinto. The recess peripheral wall is configured and sized such that as the strip of optical fiber is inserted through the fiber inlet aperture, a recess peripheral surface abuttingly guides the optical fiber strip into a generally parabolic configuration that sweeps against the recess peripheral surface while the optical fiber winds into a coil. The optical fiber winding tool is mountable over a flat surface with the peripheral edge of the guiding recess abuttingly contacting the supporting surface. A driving assembly is optionally provided for driving the strip of fiber into the guiding recess.

Abstract: A polarization-combining fused-fiber optical coupler is made of polarization maintaining (PM) fibers spliced to non-birefringent single mode (SM) fibers which are fused and drawn near the splicing to form a coupler with an adiabatic tapered profile. The linearly polarized light injected into PM fibers travels through the coupler where the power of the two polarizations is combined and transmitted to one output fiber. The method for producing such coupler involves splicing a pair of PM fibers to a pair of SM fibers, then injecting linearly polarized light into each PM fiber and fusing and drawing SM fibers to form an adiabatic coupler with maximum power transmission at a desired wavelength going to only one output fiber.

Abstract: A method of adjusting thermal dependence of an optical fiber involves hydrogenating the fiber to render it photosensitive, and then exposing it to UV radiation for such time period as to achieve the desired adjustment in the thermal dependence. In an all-fiber Mach-Zehnder interferometer, the method involves using a photosensitive fiber as one of the arms of the interferometer and exposing this photosensitive fiber to UV radiation so as to adjust the thermal dependence of the interferometer. The resulting interferometer is also part of the invention.

Abstract: A method is disclosed for securing an optical fiber to a packaging substrate with a bismuth-containing alloy of solder. For this purpose, the substrate may be provided with metallic pads or a blanket metallization to which the alloy or solder can adhere and the optical fiber is then positioned above such substrate and bonded to it with the alloy or solder. Also, a cavity or recess may be formed in the substrate in which the optical fiber is positioned and into which the alloy or solder is delivered in preformed or liquid state and is solidified in the cavity or recess while bonding the fiber. An optical assembly is also disclosed in which at least one optical fiber is bonded to the substrate by means of the bismuth-containing alloy or solder.

Abstract: A reflectionless termination is provided for an optical fiber that has a core and a cladding. The optical fiber forms part of a device which is mounted in a package and the termination fits inside the package. The termination consists of a short piece of an attenuating fiber connected at the end of the optical fiber and having a doped core which absorbs the light emanating from the core of the optical fiber.

Abstract: An optical fiber filter is produced which has a sinusoidal response or a modulated sinusoidal response with any desired amplitude and wavelength period. This is achieved by first producing an elongated adiabatic taper in a single-mode fiber which has been stripped of its protective jacket. Then, on the slope of this adiabatic taper, at each end of the central zone, there is formed a non-adiabatic taper such as to obtain a predetermined sinusoidal or modulated sinusoidal response in the filter.