Optical amplifier device

Claim 1

An optical amplifier device for an optical transmission system with bidirectional wavelength multiplex to a light transmission wave guide, said optical amplifier device comprising a first optical amplifier (OV1) for amplifying signals of a first wavelength (λ 1 ) in a first direction, said first optical amplifier (OV1) having an input and an output; a second optical amplifier (OV2) for amplifying signals of a second wavelength (λ 2 ) in a second direction, said second optical amplifier (OV2) having an input and an output; a first wavelength selective coupler (WDM1) connecting the input of the first optical amplifier (OV1) and the output of the second optical amplifier (OV2) with a light transmission wave guide (U) and a second wavelength selective coupler (WDM2) connecting the input of the second optical amplifier (OV2) and the output of the first optical amplifier (OV1) with said light transmission wave guide (U); wherein each of said wavelength selective couplers (WDM1, WDM2) has two light transmission paths (A1, A2), the dependence of transmittance on transmitted light wavelength differs along each of said light transmission paths (A1, A2) for each of said wavelength selective couplers but the transmittance along each of said light transmission paths (A1, A2) of said first wavelength selective coupler (WDM1) is equal at a first predetermined wavelength (λ i ) and the transmittance along each of said light transmission paths (A1, A2) of said second wavelength selective coupler (WDM2) is equal at a second predetermined wavelength (λ i' ); and said predetermined wavelength (λ i ) of said first wavelength selective coupler (WDM1) is different from said second predetermined wavelength (λ i' ) of said second wavelength selective coupler (WDM2).