CMOS-compatible highly efficient polarization splitter and rotator based on a double-etched directional coupler

Area of Science:

• Photonics and Optical Engineering
• Integrated Optics
• Semiconductor Devices

Background:

• Polarization management is crucial for optical communication systems.
• Efficient polarization splitters and rotators (PSRs) are essential components in photonic integrated circuits.
• Existing PSR designs often face challenges with size, efficiency, or crosstalk.

Purpose of the Study:

• To design and fabricate a highly efficient polarization splitter and rotator (PSR).
• To achieve low insertion loss and high polarization conversion efficiency.
• To demonstrate the performance of the PSR for optical communication wavelengths.

Main Methods:

• Fabrication of the PSR using 248 nm deep ultraviolet lithography.
• Utilizing a silicon-on-insulator (SOI) substrate.
• Implementing a double-etched directional coupler design with a length of 27 µm.

Main Results:

• Achieved TM-to-TE conversion loss better than 0.5 dB.
• Demonstrated TE insertion loss better than 0.3 dB.
• Obtained ultra-low crosstalk of -20 dB within the 1540-1570 nm wavelength range.

Conclusions:

• The fabricated PSR exhibits high efficiency and low loss, suitable for optical applications.
• The device's compact size and excellent performance make it a promising component for integrated photonics.
• Deep ultraviolet lithography on SOI is an effective method for creating advanced photonic devices.