Integrated Optical Directional Coupler
A directional coupler serves as an essential passive component in integrated photonic systems, allowing precise splitting or combining of optical signals between two closely positioned waveguides. Our method enables a broadband and precise characterization of the directional couplers' splitting ratio. We experimen-tally validate this approach, demonstrate its robustness against intentional errors, and compare it to a naive di-rect measurement method. Its functionality depends on evanescent field coupling, where the exponentially decaying. Based on Finite Difference Eigenmode, Finite-Difference Time-Domain simulations, and experimental measurements. The optical directional coupler, analogous to the microwave elementl of the same name, consists of paral lel channel optical waveguides sufficiently closely spaced that energy is transferred from one to another.
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