Optical array amplifier

An optical array amplifier has a first light beam shaper, a first waveguide to guide an input optical signal consisting of a plurality of wavelengths to the first beam shaper, a diffracter illuminated by light from the first beam shaper to diffract the optical signal into individual wavelengths or groups of wavelengths, a second waveguide connected to a source of optical pump energy, a second beam shaper combining optical pump energy from the second waveguide with the diffracted signal wavelengths or groups of wavelengths without the pump energy impinging on the diffracter, so that a proportion of the optical pump energy is mixed with each of the wavelengths or groups of wavelengths, and to focus the mixed optical signals onto a third waveguide connected to an optical amplifier utilizing the pump energy to cause amplification of the individual wavelengths or groups of wavelengths mixed with the corresponding proportion of pump energy. The amplifier may be implemented as a planar waveguide device. Optical attenuators connected to the outputs of the device may be controlled in dependence on the amplitude of the signals. The amplitude and/or phase of the pumping energy may also be dependent on the amplitude of the signals.