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In this work, a silicon-integrated edge coupler supporting dual-mode fiber-to-chip coupling was designed and fabricated on 220-nm-thick SOI wafer with standard CMOS-compatible fabrication process. The proposed low-complexity structure consists of a multimode interference and triple-tip inverse taper. Both LP01 and LP11 modes in the few mode fiber (FMF) can be stimulated simultaneously by the edge coupler from TE0 and TE1 modes in silicon waveguide. Such a design is compatible with broadband wavelength division multiplexing and can be scaled up to 4-polarization-mode coupling as well. Using the proposed edge coupler, 2×100-Gbps/lambda PAM4 multimode interface through dual-mode fiber was demonstrated successfully.

Grating coupler and mode converter working at 2-micron waveband were fabricated on the 600-nm-thick As2S3-on-oxide platform. Both simulation and experiment results indicate that 2-micron As2S3 components has broadened wavelength bandwidth and improved fabrication tolerance.

We use a neural network to inversely design a four-ring few-mode fiber for weak-coupling optimization so as to support MIMO-less MDM optical communication. This method provides high-accuracy, high-efficiency and low-complexity for complexed fiber design.

2-micron waveband optical interconnection at record-high-speed of 100 Gbps/lane with 100-m hollow-core photonic bandgap fiber transmission is achieved. Mode-dependent bandwidth restriction is well optimized by probabilistically shaped discrete multi-tone (PS-DMT) modulation.

We experimentally achieved the highest single-lane optical interconnection speed of 90 Gbps at 2-micron waveband, based on external modulation of discrete multi-tone (DMT), with BER under the FEC limit after 100 -m fiber transmission.

In this work, on-chip chalcogenide glass photonic integrations with several fundamental photonic building blocks are designed and fabricated based on the As 2 S 3 platform for improved 2 μm optical interconnection, achieving a broadened wavelength bandwidth and improved fabrication tolerance. A 600 nm thick As 2 S 3 strip waveguide has low propagation loss of 1.447 dB/cm at 2 μm. Broadband vertical coupling is realized by a grating coupler with 4.3 dB coupling loss. A Bragg grating filter, power splitter, Mach–Zander interferometer, and mode converter for on-chip mode division multiplexing (MDM) are also reported at 2 μm with reliable performances. Finally, a record high MDM optical interconnection capacity of 3 × 80 Gbps at 2 μm is experimentally demonstrated based on the proposed As 2 S 3 chip, drawing promising prospects for future photonic integration and high-speed interconnection at the 2 μm waveband.

Few-mode fiber (FMF) supporting many modes with weak-coupling is highly desired in mode division multiplexing (MDM) systems. The multi-parameter design of FMF becomes comparably difficult, inaccurate and time-consuming when it comes for complex fiber structures and many high order modes. In this work, we demonstrate a machine learning method using neural network to inversely design the desired FMF based on multiple-ring structure. By using the minimum index difference between adjacent modes as the weak-coupling optimization aim, we realize the inverse design of 4-ring step-index FMFs for supporting 4, 6 and 10 -mode operation, and 6-ring step-index FMF for supporting 20-mode operation. This method provides high-accuracy, high-efficiency and low-complexity for fast and reusable design of optical fibers, including particularly weak-coupling FMF in this work. It can be widely extended to a lot of fibers and has great potential for instantaneous applications in the optical fiber industry.