Ultra-compact reflective mode converter based on a silicon subwavelength structure

Area of Science:

• Photonics and Optical Engineering
• Integrated Optics
• Nanophotonics

Background:

• Mode converters are crucial components in mode-division multiplexing (MDM) systems.
• Reflective mode converters (RMCs) offer advantages by folding optical paths and enabling mode exchange.
• Efficient and compact mode converters are needed for advanced optical networks.

Purpose of the Study:

• To propose and experimentally demonstrate a silicon subwavelength structure-based reflective mode converter (RMC).
• To achieve efficient conversion from the fundamental mode (TE0) to higher-order modes (TE1, TE2, TE3).
• To validate the performance of the RMC in terms of insertion loss and crosstalk.

Main Methods:

• Design and simulation of a silicon subwavelength structure for RMC.
• Fabrication and experimental characterization of the RMC device.
• Testing RMCs for TE0 to TE1, TE0 to TE2, and TE0 to TE3 mode conversion.

Main Results:

• Demonstrated an RMC with a 2.0 µm × 2.0 µm footprint for TE0 to TE1 conversion.
• Simulated insertion loss < 0.6 dB and crosstalk < -20.3 dB (1525-1565 nm).
• Measured insertion loss < 2.2 dB and crosstalk < -16.2 dB, with simulated losses < 1.8 dB for higher-order mode conversions.

Conclusions:

• The proposed silicon subwavelength structure RMC is effective for mode conversion in optical networks.
• The RMC technology shows promise for compact and efficient mode manipulation in integrated photonics.
• The methodology is general and applicable to various mode conversion functionalities.