Reconfigurable and low-loss three-mode optical switch based on Ψ-junctions and multimode interferometers

Area of Science:

• Photonics and Optical Engineering
• Integrated Optics
• Waveguide Technology

Background:

• Mode-division multiplexing (MDM) offers enhanced data capacity in optical networks.
• Efficient optical switches are essential for routing signals in MDM systems.
• Planar lightwave circuits provide a platform for integrated optical devices.

Purpose of the Study:

• To propose and demonstrate a novel N-channel mode-division multiplexing (MDM) signal switching scheme.
• To develop a three-mode optical switch using silica planar lightwave circuit technology.
• To evaluate the performance of the fabricated optical switch for MDM applications.

Main Methods:

• Design and fabrication of a three-mode optical switch using cascaded symmetric Ψ-junctions, Mach-Zehnder interferometer (MZI) waveguides, and electrode phase shifters.
• Utilizing thermo-optic modulation for signal switching.
• Employing CMOS-compatible silica-on-silicon processing for device fabrication.

Main Results:

• The fabricated switch demonstrated low insertion loss (IL) of 3.7 ± 0.1 dB and high extinction ratio (ER) of 10.3 ± 0.5 dB at 1550 nm for individual mode switching (E11, E21, E31).
• Achieved a fast response time of <1.36 ms.
• Exhibited a wide operational bandwidth (>100 nm) with IL <5 dB and ER ≥8 dB for E11 and E21 modes.
• The switch is reconfigurable for simultaneous or individual routing of modes.

Conclusions:

• The proposed MDM optical switch enables efficient and low-loss switching of multiple modes.
• The device's performance characteristics make it suitable for various applications within MDM systems.
• This technology holds significant potential for optical interconnects in future high-capacity optical communication systems.