Multimode-based polarization independent WDM devices using different order modes for TE and TM polarizations

Area of Science:

• Photonics and Optical Engineering
• Integrated Optics

Background:

• Polarization-dependent devices limit the efficiency and complexity of wavelength division multiplexing (WDM) systems.
• Existing polarization-independent (PI) WDM solutions often require complex polarization diversity schemes.

Purpose of the Study:

• To propose and demonstrate a new approach for creating polarization-independent (PI) WDM devices using multimode configurations.
• To enable flexible device design by employing different order modes for orthogonal polarizations (TE and TM).

Main Methods:

• Development of a basic PI coupler using a multimode directional coupler and mode converters.
• Integration of the PI coupler into Mach-Zehnder interferometer (MZI) and Bragg grating bandpass filter designs.
• Optimization of phase shifters in MZI arms and use of polarization-rotating Bragg gratings for bandpass filters.

Main Results:

• Experimental demonstration of PI WDM devices, including a PI coupler, PI MZI, and PI bandpass filter.
• Achieved good spectral matching between TE and TM polarizations for device operation wavelengths.
• The proposed multimode concept effectively eliminates the need for polarization diversity schemes.

Conclusions:

• The proposed multimode-based approach offers a promising pathway to realize polarization-independent WDM functions.
• This method simplifies WDM device design and reduces system complexity compared to traditional methods.
• The flexibility in mode selection allows for novel device architectures in integrated photonics.