Passive, wavelength self-adjusting and tracking optical filter

A passive, self-adjusted filter is presented which consists of an unpumped, twin-core erbium-doped fibre. The filter characteristics depend on the fibre and optical parameters. For a fibre NA of 0.3, the optimum filter performance is achieved for average optical powers of about 0dBm (± 3dB). The device can also operate as a soliton sliding filter providing a filter centre-wavelength offset of ~0.1nm from the incoming centre wavelength