Fig. 1. Silicon waveguide devices based on SOI have low two-photon absorption and low BOX absorption in the short-wavelength mid-IR band^{[22, 25-26]}

Fig. 2. Silicon waveguides in the short-wavelength mid-IR band. (a) Measurement result of optical loss of the TE₀-mode strip (left) and rib (right) silicon waveguides^[42]; (b) Scanning electron microscope (SEM) images of the silicon waveguide fabricated with the MPW service^[27]; (c) SEM image of the SMW cross section^[44]; (d) Schematic of the subwavelength-grating-cladding suspended slot waveguide^[45]

Fig. 3. Silicon grating couplers in the short-wavelength mid-IR band. (a) SEM image of the shallow-etched uniform grating coupler^[53]; (b) Schematic of the polysilicon/silicon grating coupler^[40]; (c) SEM image of the focusing subwavelength grating coupler fabricated with the MPW service^[27]; (d) Measurement results of the ultra-thin focusing subwavelength grating coupler^[55]

Fig. 4. Silicon micro-resonators in the short-wavelength mid-IR band. (a) SEM image of the racetrack microring resonator^[60]; (b) Schematic picture of the suspended membrane ring resonator^[44]; (c) Microscope image of the tunable microring resonator^[61]; (d) SEM image of the microdisk resonator with the subwavelength grating structure^[63]

Fig. 5. Silicon multiplexing/demultiplexing devices in the short-wavelength mid-IR band. (a) The transmission spectrum image of different channels (left) and microscope image (right) of the AWG^[69]; (b) Microscope image of the echelle grating^[68]; (c) Schematic of the silicon multi-mode multiplexing/demultiplexing devices^[71]; (d) Measured bit error rate (BER) of the silicon multi-mode multiplexing/demultiplexing devices as a function of the received optical signal-to-noise ratio (OSNR)^[71]

Fig. 6. Nonlinear optical waveguide devices in the short-wavelength mid-IR band. (a) Wavelength conversion across more than one octave based on FWM^[74]; (b) SCG based on the SOI waveguide^[77]; (c) Schematic of the Kerr frequency comb generation in the microring resonator^[82]; (d) Spectrum and intracavity power of the KFC based on the Si/Ge waveguide^[82]

Fig. 7. Optoelectronic waveguide devices in the short-wavelength mid-IR band. (a) Cross-sectional schematic diagram of the active region of the p-i-n diode phase-shifter^[83]; (b) Optical microscope image of the MZM ^[84]; (c) Schematic of the racetrack microring resonator-enhanced WSi nanowire photodetector. The red line indicates the waveguide on which the WSi nanowire is integrated^[91]; (d) SEM image of the cross-section of the Zn²⁺-implanted Si waveguide photodiodes ^[92]