Abstract

We describe a new design of an electro-optic switch with a flat "digital" voltage response in which precise control of switching voltage is not required in order to achieve low crosstalk. Conventional switches require precise control of voltage in order to achieve a switched state with very low crosstalk. For example, the directional coupler requires an electro-optically induced phase shift of ΔβL/π = √3 between the waveguide pair to switch.[1] The I₀-V characteristic for directional coupler with L=l_c is shown in Figure 1. In order to keep the crosstalk between the two outputs below -30db, one needs to apply and maintain the switching voltage (ΔβL/π) to within a very narrow range of ±0.03 for the "cross-state" and 1.69 to 1.77 for the "straight-through" state. Therefore, even a small voltage drift can cause problem. Precise control of the applied switching voltage must be maintained at all time.

© 1988 Optical Society of America