Broadband and highly efficient integrated polarization rotator designed by topology optimization.

Area of Science:

• Photonics
• Optical Engineering
• Materials Science

Background:

• Polarization rotators are essential components in polarization-diversity systems like coherent transceivers.
• Efficient and compact polarization rotators are needed to improve optical system performance.

Purpose of the Study:

• To design and simulate an ultra-compact and efficient silicon polarization rotator.
• To utilize inverse design and adjoint methods for optimizing device topology.

Main Methods:

• Employed inverse design methodology based on the adjoint method for topology optimization.
• Simulated device performance, including polarization conversion loss and crosstalk, at a 1550 nm wavelength.

Main Results:

• Achieved a polarization conversion loss of 0.67 dB and crosstalk of -18 dB for a 7 µm x 1.2 µm device.
• Demonstrated high coupling efficiency and low crosstalk over a bandwidth exceeding 100 nm (1500-1600 nm).
• Maintained polarization conversion loss below 0.82 dB and crosstalk below -18 dB across the 100 nm bandwidth.

Conclusions:

• The designed silicon polarization rotator is ultra-compact and highly efficient.
• The inverse design approach effectively optimized the device for excellent performance.
• This compact rotator is suitable for integration into advanced optical communication systems.