Compact polarization beam splitter assisted by subwavelength grating in triple-waveguide directional coupler

Area of Science:

• Photonics and Optical Engineering
• Integrated Optics
• Nanophotonics

Background:

• Polarization beam splitters (PBS) are crucial for optical communication and interconnection systems.
• Efficient and compact PBS designs are needed to advance integrated photonic devices.

Purpose of the Study:

• To propose and investigate a novel PBS design using subwavelength gratings (SWG) on a silicon-on-insulator (SOI) platform.
• To achieve high performance in terms of extinction ratio and insertion loss for optical signal manipulation.

Main Methods:

• Design of a triple-waveguide directional coupler incorporating an SWG waveguide as a bridge between two silicon waveguides.
• Optimization of SWG grating period and duty ratio to tailor dispersion and achieve mode selectivity.
• Investigation of device performance at a wavelength of 1550 nm on a 340-nm SOI platform.

Main Results:

• The proposed PBS demonstrates efficient coupling for the TE mode via the SWG waveguide.
• The TM mode passes through the device with minimal influence.
• Achieved extinction ratios exceeding 27 dB and insertion losses below 0.3 dB with a device length of 6.5 μm.

Conclusions:

• The SWG-based PBS offers a compact and high-performance solution for polarization manipulation in optical systems.
• The tailorable dispersion of SWG waveguides provides design flexibility for integrated photonic circuits.
• This technology holds promise for advancing optical interconnections and communication networks.