Abstract: Driven by the development in big data services, the conventional optical fiber communication window was shifting from C-band to C+L band to meet the continuously increasing demand for bandwidths. Exploiting new wavebands became a crucial problem within the optical communications community. The 2 μm spectral range between near-infrared and mid-infrared held advantages of low transmission loss and broad gain bandwidth, which made it a promising candidate for the next window of free space laser and optical fiber communications. Even though the commercialization of the 2 μm optoelectronic devices was at early stage, recorded single-lane 100 Gbit/s transmission had been achieved in the laboratory. In the meantime, developing functional elements in this wavelength range was attracting extensive interests. In this paper, the recent advances of 2 μm silicon photonic device were introduced. Photonic integrated components on other platforms like III-V, thin-film lithium niobate, silicon nitride, and chalcogenide glass were also discussed. Finally, the 2 μm was envisioned on-chip photonic integrated devices.