A Novel Π - Phase Shifter in Integrated Optics

The Integrated Optics has resulted in miniaturization of optical devices. Bent waveguides have replaced straight waveguides in optical integrated circuits for such reasons. In the proposed work, curved/bent waveguide is basic structure for generating delay and hence the phase shift. A differential phase shift is obtained by the differential length change between the straight waveguide and a S-bend waveguide. We discuss a 1-bit delay line that produces the required phase shift. In the design the length of the straight waveguide is 2000μm. We obtain a phase shift of π radians for a differential length of 0.3629μm. Ti diffused Lithium niobate waveguides are employed. An extra-ordinary refractive index of 2.13806 is considered for the substrate. This is a phase delay method, in which the optical phase shift produced is transferred to RF domain by heterodyning as compared to the true time delay methods used previously with larger switching speeds in the order of hundreds of pico secs.