Translation of decoupling circuits into photonic devices

摘要

Several circuits, the following two are denoted by (A) and (B), are needed for decoupling of lightwave circuits (LWCs) and for a future transfer function matrix (TFM) synthesis of LWCs. (A) Controller matrix of a feedback (FB) which is an optical network composed of (ⅰ) variable weighted distributed FBs, implemented by electro-optically tunable gratings at waveguides (WGs) and (ⅱ) optical isolators (OIs) or (ⅲ) switches, respectively, for the correct flow of the optical field in the network. The controller matrix may be generalized to include space-variable elements according to a step function by step-wise arranged electrodes at the substrate of the gratings. Another generalization is the introduction of several wavelengths by subsequently arranged gratings of different spacing at the WGs of the controller matrix. The inclusion of such controller matrices at several wavelengths into a WDM switch requires various frequency converters (FCs) for the non-blocking operation. (B) Optical differentiator with regard to the longitudinal space coordinate of a WG which is composed of (ⅰ) reflection-type Mach-Zehnder interferometers (RMZIs) arranged at a (ⅱ) fish-bone WG pattern for the implementation of the parallel RMZIs. The interleaved organization of the arms in (ⅱ) provides the approximate differentiation of the optical field in a WG. The application of (A) and (B) to the advanced control of couplers is proposed (derivative FB). The paper presents circuits and their principles rather than their evaluation. The final goal is the photonic integration of the presented decoupling circuits.