A widely tunable optical filter using ladder-type structure

A novel widely tunable optical filter with a ladder-type structure is proposed. The device decreases the electrode area, compared with a tunable filter using an arrayed waveguide grating filter. It is fabricated using the InGaAsPInP material system, and current injection is employed to change the refractive index of the waveguide. The device exhibits a tuning range of 58 nm and a switching time of less than 10 ns.