Ultracompact 1310/1550 nm wavelength demultiplexer based on subwavelength grating-assisted multimode interference coupler

An ultra-compact 1310/1550 nm wavelength demultiplexer based on multimode interference (MMI) coupler assisted by subwavelength gratings (SWGs) is proposed. Two parallel SWG-based slots are inserted into the MMI section symmetrically. Equivalent refractive index and width of the SWG are designed properly to reduce the device length while keeping a low insertion loss (IL) and high extinction ratio (ER). In this way, the device length shrinks to 34.48 mu m. The performance when the device working as a multiplexer and as a demultiplexer are both investigated. From the transmission spectrum, ILs of < 0.24 dB, ERs of larger than 15.2 dB and broad 1-dB bandwidths of larger than 90 nm are obtained for the two wavelengths. (C) The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License.

Automated summary

An ultra-compact 1310/1550 nm wavelength demultiplexer based on multimode interference coupler assisted by subwavelength gratings is proposed, with the device length reduced to 34.48 μm while maintaining low insertion loss and high extinction ratio. The performance of the device as both a multiplexer and demultiplexer is investigated, achieving insertion losses of < 0.24 dB, extinction ratios of > 15.2 dB, and broad 1-dB bandwidths of > 90 nm for the two wavelengths.