Oxide Cladding Polarization Rotator-Splitters for Low Crosstalk

The patent changes the physical parameters of the waveguide structure by introducing oxide claddings with specific refractive indices. The cladding layers are designed with precise thicknesses (first cladding layer: 1-5 μm, second cladding layer: 1-5 μm) and material compositions to optimize mode conversion efficiency. This parameter optimization enables effective polarization rotation and mode conversion while minimizing conversion loss, thereby resolving the contradiction between enhanced productivity and reduced energy loss.

The patent employs composite material structures consisting of semiconductor waveguide cores surrounded by oxide claddings (such as silicon dioxide, silicon nitride, or silicon oxynitride). This composite configuration creates distinct refractive index contrasts that enable precise control over optical mode propagation and conversion. The composite structure achieves low crosstalk and conversion loss while maintaining high bandwidth capability, thus resolving the technical contradiction.

The patent optimizes geometric parameters including waveguide width (500 nm - 2 μm), waveguide length (10 μm - 1 mm), and cladding thickness (1 μm - 5 μm) to achieve precise mode separation. By carefully controlling these parameters, the device achieves effective polarization rotation and mode conversion while minimizing crosstalk between different signal channels, thus resolving the contradiction between enhanced productivity and reduced harmful effects.

The use of oxide claddings with different refractive indices creates distinct optical confinement regions that effectively separate different polarization modes. The composite structure of semiconductor core and oxide cladding enables precise control over mode propagation characteristics, achieving low crosstalk while maintaining high bandwidth capability for multiplexed signal transmission.

The patent combines multiple functions (polarization rotation, mode conversion, signal splitting, and signal combining) into a single integrated waveguide structure. The mode-conversion section and coupling section are merged into one continuous waveguide path with optimized geometry, eliminating the need for separate discrete components. This integration maintains high signal processing efficiency while reducing overall device complexity and fabrication difficulty.

The waveguide structure is designed to perform multiple functions simultaneously: it acts as a polarization rotator, mode converter, and signal splitter/combiner depending on the input signal characteristics. This multi-functional design achieves high demultiplexing and multiplexing efficiency without requiring separate dedicated components for each function, thereby reducing device complexity while maintaining high productivity.