Novel add/drop filters for wavelength-division-multiplexing optical fibre systems using a Bragg grating assisted mismatched coupler

We have demonstrated a novel add/drop filter for use in wavelength-division-multiplexing (WDM) optical fibre systems based on a Bragg grating assisted mismatched coupler. The device is potentially easy to fabricate and stable, because it is not interferometric, unlike all similar devices demonstrated so far, and, therefore, does not need fine tuning of the interferometers during fabrication and does not have to maintain the balance of the interferometers during its lifetime