Apodized Silicon-on-Insulator Bragg Gratings

An accurate control of the apodization profile is still an issue for integrated Bragg grating filters fabricated in silicon-on-insulator because of the high modal confinement of these waveguides. In this letter, we present two fabrication-friendly apodization techniques that are compatible with deep UV lithography and can be used in mass-production of photonic-integrated circuits. These techniques are reliable even for weak effective index modulation amplitude, thus opening the door to the fabrication of long and elaborate grating structures.