Abstract: The present invention relates to a method and a device for determining the cut-off wavelength of an optical fibre. A first aspect of the present invention is to provide a method for determining the cut-off wavelength of an optical fibre, which method provides a stable measurement, which measurement is substantially independent of the exact fibre position.

Abstract: An apparatus for aligning monomode optical fibers utilizes a first optical coupler for injecting light into a straight section of a first fiber through its buffer, a first pin for bending the first fiber downstream of the first optical coupler to convert cladding modes into core modes, a second pin for converting core modes into cladding modes in a second optical fiber, a second optical coupler for withdrawing light from the second optical fiber through its buffer, and feedback control to optimize the amount of light transferred from the first fiber core to the second fiber core.

Abstract: The invention provides a coupling device for monochromatic optical signals based on the amplitude division method. The optical signal emerging from one light guide is divided by means of one or more diffraction gratings among three or more outgoing light guides. Inversely, the optical signals from a number of light guides can be combined into one optical signal. Such a coupling device has a high optical efficiency, is mode-independent and produces small differences in light intensity between the branch signals.