Fast tunable optical filter using cascaded Mach-Zehnder Interferometers with apodized sampled gratings

We demonstrate a novel tunable optical filter using cascaded Mach-Zehnder interferometers with apodized sampled gratings (ASGs). The ASGs are fabricated using an InGaAsP-InP deep-ridge waveguide with vertical-groove surface grating to obtain a high extinction ratio by sidelobe suppression. The proposed filter exhibits the total free-spectral range of 16 nm, an extinction ratio of 20 dB, and a 3-dB transmission bandwidth of 32 GHz.