(285g) Modeling and Design of Metal-Semiconductor Photonic Waveguides

Optical waveguides are common structures in photonic devices. To have better light-emitting performance and efficient use-of-energy, specific periodic structures with proper materials can generate stable wavelengths required in scientific research and engineering applications. 

How to define the geometry and select proper materials for this model will be described first. This waveguide structure generally has three types of semiconductor layers: an active layer, a cladding layer, a buffer layer, plus a corrugated metal-grating layer. The interface between the metallic layer and its adjacent semiconductor layer has sinusoidal corrugation. To have a stable wavelength, a specific grating period is determined. The corrugation depth of this grating can greatly affect the magnitude of this backward wave mode-coupling. The light beam is emitted from the active layer. However, the active layer thickness can affect this coupling in a more complicated way. The improper design and manufacturing of the active layer thickness can cause this coupling to become smaller or even vanish. Therefore, an optimal range of the active layer thickness is important to make a photonic device function properly.

This work demonstrates a multi-parametric model to compute the mode-coupling, which is important to the analysis and integration of electronic and photonic devices. For such a hybrid metal-semiconductor structure with built-in corrugation, a proper technique, by considering the electronics and photonics, needs to be utilized to solve this computational complexity. This work modifies a prior model which only can work for ideal perfect-metal gratings. Now, this modified model can deal with the practical metal, gold, which can be used in the real fabrication process. Numerical results show comparisons between the ideal model and modified practical model. Two computational methods are used to verify the accuracy of the above results for both models. Further physical interpretation and discussion can support and explain the above results.