Abstract: A spectrally selective optical switch is disclosed. The switch comprises a first and a second optical waveguide each having a light guiding structure arranged to guide light along a predetermined path, the optical waveguides being arranged adjacent and parallel to each other; an external resonator defined by a first and a second mirror, said first and said second mirror being provided on opposite sides and outside of said first and second light guiding structures, and said external resonator being resonant to a specific wavelength; and a deflector provided in each of said first and second optical waveguide, the deflectors being arranged to deflect light propagating in one of the light guiding structures to the other light guiding structure by operation of said external resonator. A matrix switch is also disclosed.

Abstract: The invention relates to methods and arrangements for channel balancing of a wavelength division multiplexed optical signal. Channel balancing according to the invention is performed by using a resonator that provides a selection region in which a selected channel has a substantially increased poser density relative to channels out of resonance. The selected channel is attenuated a desired amount, i.e. a desired amount of power is removed therefrom, by adjusting the properties of the selection region. In a preferred embodiment, attenuation is achieved by adjusting the selection region such that destructive interference is obtained for the selected channel in a fiber carrying tile multiplexed optical signal.

Abstract: The invention relates to the coupling of light to and from an optical waveguide, such as an optical fiber. Light of a specific wavelength is deflected out from the fiber, or into the fiber, in a substantially transverse direction with respect to the propagation direction of light in the waveguide, by a deflector 16 arranged in the fiber core 10. Wavelength selectivity of the deflector 16 is provided by a Bragg grating means located in the fiber core 10. The deflected light is collimated, or converged towards a focus, by an interface 15 between a cladding 11, having one index of refraction, and an outer medium 12, having another index of refraction. The ratio between the radius of the cladding 11 and the radius of the core 10 made sufficiently small for the collimating, or converging, effect to appear.

Abstract: In a semiconductor laser of the BH-type comprising a lateral current blocking structure which is constituted of an n-p-n-p- or n-SI-n-p-sequence of layers, located on both sides of a buried active region, one or more thin layers are inserted between the second n-doped layer and the second p-doped layer. The thin, extra layers are p-doped and consist of alternatingly materials having a high bandgap and a low bandgap. These thin layers provide a larger forward voltage drop at moderate to high current densities and thereby give a better current confinement in the laser, what in turn gives a higher optical output power and a smaller deviation of the output power/current characteristic thereof from a linear behavior.