Abstract
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 μm. 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.
Highlights
With continuously increasing demand for broadband services, such as big data, cloud computing, and large-capacity communications, wavelength division multiplexing (WDM) technology has been widely used thanks to its ability to increase the number of channels and the transmission bandwidth.[1]
We propose an ultra-compact 1310∕1550 nm wavelength demultiplexer based on multimode interference (MMI) coupler with two parallel subwavelength grating (SWG)-based slots
We demonstrated the design and performance evaluation of the 1310∕1550 nm wavelength demultiplexer based on MMI coupler with two SWG slots
Summary
With continuously increasing demand for broadband services, such as big data, cloud computing, and large-capacity communications, wavelength division multiplexing (WDM) technology has been widely used thanks to its ability to increase the number of channels and the transmission bandwidth.[1]. Wavelength demultiplexers using cascaded silicon micro-ring resonators are compact and scalable, but they are limited by the small bandwidth and the high temperature sensitivity. Directional couplers suffer from the limited bandwidth and fabrication tolerance due to their precise phase matching condition. MMI-based demultiplexers that provide a relatively broad optical bandwidth, relax fabrication tolerance, and low IL have drawn much attention as the most potential candidates. To reduce the device length, slotted MMI devices have been proposed. It has been verified that introducing N slots reduces the self-imaging length by a factor of N þ 1.13 effective indices of slots need to be carefully adjusted by varying etching depths, which makes the fabrication process complicated
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