A method and device is provided for reducing optical transmission impairments, particularly nonlinear effects, of at least one link Said method comprising the following steps: extracting a phase information (Δθ) from an optical signal (120) received via that at least one link, determining a nonlinear coefficient (γ), associated with the at least one link, based on the phase information (Δθ), applying a control mechanism (202) using the nonlinear coefficient (γ). Furthermore, a communication system is suggested comprising said device.