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 InGaAsP-InP 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.