Optical Semiconductor Device Thickness Control

The patent transitions from a uniform thickness design to a graded thickness profile by introducing intermediate layers with varying thicknesses between the active layer and the optical waveguide layer. This dimensional variation in the thickness parameter allows the optical waveguide layer to be thicker overall while maintaining a gradual transition at the connection interface, thereby reducing light reflection caused by abrupt thickness changes.

The patent applies different thickness characteristics to different regions: the optical waveguide layer is made thicker in the modulation area to reduce internal losses, while intermediate layers are designed with gradually varying thicknesses at the connection interface to minimize reflection. This local differentiation of thickness quality resolves the contradiction between reducing energy loss and preventing harmful reflection.

The patent divides the transition region between the active layer and optical waveguide layer into multiple intermediate layers with progressively varying thicknesses. This segmentation of the thickness transition prevents the formation of a single large step, thereby maintaining coupling efficiency while allowing the optical waveguide layer to be thicker for improved modulation performance.

By introducing intermediate layers with graded thicknesses, the patent creates a multi-dimensional thickness profile rather than a simple binary transition. This dimensional approach allows the optical waveguide layer to achieve greater thickness for better modulation performance while the intermediate layers provide a gradual transition that preserves coupling efficiency.