Tunable optical mode converter based on SOI asymmetric channel waveguides

An optical mode converter based on asymmetric dual channel waveguides is reported and analyzed. The first channel is infiltrated with nematic liquid crystal (NLC) material while the second one has BK7 glass core. The first higher order mode of the NLC core is coupled to the fundamental mode of the neighboring core with high coupling efficiency. The full vectorial finite difference method is utilized to study the modal characteristics of the reported design. The geometrical and material properties of the proposed mode converter are studied to achieve mode conversion with high wavelength selectivity and compact device length. In addition, the effect of temperature variation is also studied. Compact device length of 515.2 $\mu$m is achieved at $\lambda$=1.55$\mu$m. Therefore, the proposed design can be used efficiently in integrated photonic circuits.