Abstract: A method for measuring and monitoring the state of polarization (SOP) of a polarization maintaining (PM) fiber using a narrowband fiber Bragg grating (FBG) written on the same is provided. The PM fiber comprises a first narrowband reference FBG which is used as a reference to measure and monitor the SOP of the PM fiber. Due to the birefringence properties of the PM fiber, the reference FBG typically reflects two narrowband spectra, each having a central wavelength; one in the slow axis and one in the fast axis. By measuring the intensity of the reflected spectra in each axis and by tuning the fiber with a polarization controller, it is possible to adjust the fiber to a predetermined SOP. Accurate measures of optical properties (e.g. reflectivity) of optical devices (e.g. a FBG grating), according to the predetermined SOP, are possible.

Abstract: A multimode fiber coupler has a structure in which a plurality of tapered pump fibers are coupled laterally to a multi-clad fiber, such as a double clad fiber (DCF). Such coupler is produced by first forming a plurality of tapered pump fibers and positioning them around the multi-clad fiber, thus forming a fiber bundle. Then, the fiber bundle is twisted and fused so that the input pump fibers converge towards a waist and then diverge from it. The diverging portions of the pump fibers may be removed from the structure. Also, at the waist, the structure may be cleaved and the portion with the converging pump fibers is then spliced with a multi-clad fiber which is similar or identical to the one in the middle of the bundle.

Abstract: An all-fiber, phase controlled interferometer device is disclosed as well as its method of manufacture. This device is suitable for use in an optical DPSK demodulation system. It is comprised of two optical fiber couplers, each having two input and two output ports and two branches between the couplers of unequal length. The couplers have a splicing ratio of 50% over the wavelength operating range of the device. The two branches between the couplers are shaped to provide one bit of delay between the branches and are also shaped to make a compact device. Also, the two branches are formed in such a manner as to minimize birefringence in the device. In addition, a fiber heater is provided to heat the longer branch so as to obtain phase control of the interferometer. The method of producing such a device is also disclosed.

Abstract: A package for an optical fiber device is disclosed. It has a high thermal conductivity packaging substrate surrounding the optical fiber device and has adhesive bonds at each end anchoring the optical fiber device to the substrate. The adhesive bonds are made of a material that has high transparency in damp heat as well as a high glass transition temperature and is capable of withstanding temperatures of over 100° C. The packaging substrate has a high absorption capacity and a CTE in relation to the CTE of the adhesive bond, such as to compensate for any variation in the adhesive bond due to temperature variations. This allows to limit mechanical stress in the optical fiber device within the package.

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.