Fabrication of analog- and digital-modulated pitch-variable gratings using silicon-on-insulator substrates

We fabricated pitch-variable gratings using silicon microactuators, which are highly compatible with micro-electro-mechanical systems technologies. To obtain a large change in diffraction angle with a small driving force, the grating period was designed to be as small as 4 μm. Two types of pitch-variable grating, namely, thermal-driven analog-modulated grating and electrostatic-driven digital-modulated grating, were newly designed and fabricated. Silicon-on-insulator substrates were used for the fabrication. Both gratings were fabricated with high accuracy. The changes in diffraction angles agreed well with the calculated values.