Ultra-compact low loss polarization insensitive silicon waveguide splitter.

Area of Science:

• Photonics
• Integrated Optics
• Waveguide Devices

Background:

• Cascaded Y junctions in optical systems can cause unwanted spectral fringes when coupled with multimode waveguides.
• Existing solutions may lack compactness or introduce polarization dependence.

Purpose of the Study:

• To design and demonstrate a novel wavelength-insensitive 3-dB optical power splitter.
• To address spectral fringe issues and maintain Y-splitter advantages like polarization insensitivity and ultra-compactness.

Main Methods:

• Design of a multimode interferometer (MMI) based 3-dB splitter.
• Experimental demonstration and characterization of the MMI splitter's performance.
• Fabrication of the device with a footprint of 1.5 × 1.8 µm(2).

Main Results:

• The developed MMI splitter exhibits wavelength insensitivity.
• Achieved polarization insensitivity, similar to Y-splitters.
• Measured ultra-compact footprint, nearly one order smaller than previous MMI splitters.
• Low measured excess losses: -0.11 dB for TE and -0.18 dB for TM modes at telecom wavelengths.

Conclusions:

• The MMI-based 3-dB splitter effectively solves spectral fringe problems associated with Y-junctions.
• This device offers a superior alternative for integrated photonic circuits requiring compact, low-loss, and polarization-insensitive power splitting.