Compact fabrication-tolerant subwavelength-grating-based two-mode division (de)multiplexer

Area of Science:

• Photonics and Optical Engineering
• Materials Science for Photonic Devices

Background:

• Expanding bandwidth and capacity are critical for modern communication systems.
• Subwavelength gratings (SWGs) offer advantages like miniaturization, fabrication tolerance, and wider bandwidths due to reduced field confinement and dispersion.
• Tuning SWG duty cycles can further reduce device loss.

Purpose of the Study:

• To propose and design a novel, compact, and fabrication-tolerant mode division (de)multiplexer utilizing subwavelength gratings (SWGs).
• To demonstrate the performance of the SWG-based device for high-capacity optical communication applications.

Main Methods:

• Design of a two-mode division (de)multiplexer based on subwavelength grating (SWG) principles.
• Characterization of device performance, including transmission, loss, and crosstalk over a range of wavelengths.

Main Results:

• Achieved a flat-top transmission of >0.89 (loss <0.5 dB) over a 65 nm bandwidth (1500-1565 nm), covering the C-band.
• Demonstrated crosstalk below -10 dB over a broad bandwidth of approximately 120 nm.
• Total device loss (multiplexer and demultiplexer) was less than 1 dB.

Conclusions:

• The proposed SWG-based mode division (de)multiplexer is compact, fabrication-tolerant, and exhibits excellent performance metrics.
• The device is a promising candidate for enabling high-capacity optical communications.
• It is suitable for integration into both conventional and entirely SWG-based silicon photonic circuits.