[1] Z Li, A Heidt, N Simakov, et al. Diode-pumped wideband thulium-doped fiber amplifiers for optical communications in the 1800-2050 nm window. Optics Express, 21, 26450-26455(2013).

[2] P Roberts, F Couny, H Sabert, et al. Ultimate low loss of hollow-core photonic crystal fibres. Optics Express, 13, 236-244(2005).

[3] M Petrovich, F Poletti, J P Wooler, et al. Demonstration of amplified data transmission at 2 microm in a low-loss wide bandwidth hollow core photonic bandgap fiber. Optics Express, 21, 28559-28569(2013).

[4] Shen W, Du J, Sun L, et al. 100Gbps 100m hollowce fiber optical interconnection at 2micron waveb by PSDMT [C]Optical Fiber Communications Conference Exposition, 2020: 1.

[5] Z Liu, Y Chen, Z Li, et al. High-capacity directly modulated optical transmitter for 2-μm spectral region. Journal of Lightwave Technology, 33, 1373-1379(2015).

[6] K Xu, L Sun, Y Xie, et al. Transmission of IM/DD signals at 2 μm wavelength using PAM and CAP. IEEE Photonics Journal, 8, 1-7(2016).

[7] Shen W, Du J, Wang C, et al. Single lane 90Gbps optical interconnection at 2micron waveb [C]Optoelectronics Communications Conference, 2019: 36.

[8] W Shen, J Du, L Sun, et al. Low-latency and high-speed hollow-core fiber optical interconnection at 2-micron waveband. Journal of Lightwave Technology, 38, 3874-3882(2020).

[9] Y Gu, Y Zhang, Y Cao, et al. 2.4 µm InP-based antimony-free triangular quantum well lasers in continuous-wave operation above room temperature. Applied Physics Express, 7, 032701(2014).

[10] R Wang, S Sprengel, A Malik, et al. Heterogeneously integrated III-V-on-silicon 2.3 x μm distributed feedback lasers based on a type-II active region. Applied Physics Letters, 109, 221111(2016).

[11] K Kiani, H Frankis, R Mateman, et al. Thulium-doped tellurium oxide microring lasers integrated on a low-loss silicon nitride platform. Optical Materials Express, 11, 3656-3665(2021).

[12] N Li, E Magden, Z Su, et al. Broadband 2-µm emission on silicon chips: Monolithically integrated Holmium lasers. Optics Express, 26, 2220-2230(2015).

[13] P Latawiec, V Venkataraman, J Burek, et al. On-chip diamond Raman laser. Optica, 2, 924-928(2015).

[14] N Volet, A Spott, J Stanton, et al. Semiconductor optical amplifiers at 2.0-µm wavelength on silicon. Laser Photonics Reviews, 11, 1600165(2017).

[15] K Kiani, H Frankis, R Mateman, et al. Thulium-doped tellurium oxide waveguide amplifier with 7.6 dB net gain on a silicon nitride chip. Optics Letters, 44, 5788-5791(2019).

[16] R Wang, S Sprengel, M Muneeb, et al. 2 μm wavelength range InP-based type-II quantum well photodiodes heterogeneously integrated on silicon photonic integrated circuits. Optics Express, 23, 26834-26841(2015).

[17] M Nedeljkovic, R Soref, G Mashanovich. Free-carrier electrorefraction and electroabsorption modulation predictions for silicon over the 1-14μm infrared wavelength range. IEEE Photonics Journal, 3, 1171-1180(2011).

[18] D Li, Y Liu, Q Song, et al. Millimeter-long silicon photonic antenna for optical phased arrays at 2-μm wavelength band. IEEE Photonics Journal, 13, 1-7(2021).

[19] Camp M A Van, S Assefa, D Gill, et al. Demonstration of electrooptic modulation at 2165 nm using a silicon Mach-Zehnder interferometer. Optics Express, 20, 28009-28016(2012).

[20] W Cao, D Hagan, D Thomson, et al. High-speed silicon modulators for the 2  μm wavelength band. Optica, 5, 1055-1062(2018).

[21] Li W, Li M, Zhang H, et al. 50 Gbits silicon modulat operated at 1950 nm [C]Optical Fiber Communications Conference Exposition, 2020: 4.

[22] X Wang, W Shen, W Li, et al. High-speed silicon photonic Mach–Zehnder modulator at 2 μm. Photonics Research, 9, 535-540(2021).

[23] Shen W, Zhou G, Du J, et al. Highspeed silicon microring modulat at 2μm waveb [C]Optoelectronics Communications Conference, 2021: 7.

[24] C Wang, M Zhang, X Chen, et al. Integrated lithium niobate electro-optic modulators operating at CMOS-compatible voltages. Nature, 562, 101-104(2018).

[25] B Pan, J Hu, Y Huang, et al. Demonstration of high-speed thin-film lithium-niobate-on-insulator optical modulators at the 2-microm wavelength. Optics Express, 29, 17710-17717(2021).

[26] R Anthony, D Hagan, D Genuth-Okon, et al. Extended wavelength responsivity of a Germanium photodetector integrated with a silicon waveguide exploiting the indirect transition. IEEE Journal of Selected Topics in Quantum Electronics, 26, 1-7(2020).

[27] J Ackert, D Thomson, L Shen, et al. High-speed detection at two micrometres with monolithic silicon photodiodes. Nature Photonics, 9, 393-396(2015).

[28] S Xu, W Wang, Y Huang, et al. High-speed photo detection at two-micron-wavelength: technology enablement by GeSn/Ge multiple-quantum-well photodiode on 300 mm Si substrate. Optics Express, 27, 5798-5813(2019).

[29] B Tossoun, J Zang, S Addamane, et al. InP-based waveguide-integrated photodiodes with InGaAs/GaAsSb type-II quantum wells and 10-GHz bandwidth at 2 μm wavelength. Journal of Lightwave Technology, 36, 4981-4987(2018).

[30] Y Yin, R Cao, J Guo, et al. High‐speed and high‐responsivity hybrid silicon/Black‐Phosphorus waveguide photodetectors at 2 µm. Laser & Photonics Reviews, 13, 1900032(2019).

[31] J Guo, J Li, C Liu, et al. High-performance silicon-graphene hybrid plasmonic waveguide photodetectors beyond 1.55μm. Light: Science & Applications, 9, 1-11(2020).

[32] J Wun, Y Wang, Y Chen, et al. GaSb-based p-i-n photodiodes with partially depleted absorbers for high-speed and high-power performance at 2.5μm wavelength. IEEE Transactions on Electron Devices, 63, 2796-2801(2016).

[33] B Tossoun, R Stephens, Y Wang, et al. High-speed InP-based p-i-n photodiodes with InGaAs/GaAsSb type-II quantum wells. IEEE Photonics Technology Letters, 30, 399-402(2018).

[34] Y Chen, Z Xie, J Huang, et al. High-speed uni-traveling carrier photodiode for 2  μm wavelength application. Optica, 6, 884-889(2019).

[35] R Mcintyre. Multiplication noise in uniform avalanche diodes. IEEE Transactions on Electron Devices, 13, 164-168(1966).

[36] R People, J Bean. Calculation of critical layer thickness versus lattice mismatch for Ge_xSi_1−x/Si strained‐layer heterostructures. Applied Physics Letters, 47, 322-324(1985).

[37] H Zhou, S Xu, Y Lin, et al. High-efficiency GeSn/Ge multiple-quantum-well photodetectors with photon-trapping microstructures operating at 2 microm. Optics Express, 28, 10280-10293(2020).

[38] H Ma, H Yang, B Tang, et al. Passive devices at 2 µm wavelength on 200 mm CMOS-compatible silicon photonics platform. Chinese Optics Letters, 19, 071301(2021).

[39] J Li, Y Liu, Y Meng, et al. 2 μm wavelength grating coupler, bent waveguide, and tunable microring on silicon photonic MPW. IEEE Photonics Technology Letters, 30, 471-474(2018).

[40] L Zhang, W Zhang, X Wang, et al. Investigation of Ge₂₀Sb₁₅Se₆₅ photonic crystal slab waveguides with slow light at infrared wavelength. Optical Materials Express, 3, 1438-1443(2013).

[41] W Shen, P Zeng, Z Yang, et al. Chalcogenide glass photonic integration for improved 2  μm optical interconnection. Photonics Research, 8, 1484-1490(2020).

[42] Muratsubaki T, Fujisawa T, Sawada Y, et al. Fabricationtolerant fourmode waveguide crossing based on PhClike subwavelength structures at 2 µm [C]Advanced Photonics Congress, 2021: 3.

[43] Z Ruan, L Shen, S Zheng, et al. Subwavelength grating slot (SWGS) waveguide at 2 μm for chip-scale data transmission. Nanophotonics, 7, 865-871(2018).

[44] M Lamy, C Finot, A Parriaux, et al. Si-rich silicon-nitride waveguides for optical transmissions and towards wavelength conversion around 2 µm. Applied Optics, 58, 5165-5169(2019).

[45] Li J, Liu L, Sun W, et al. The 2μm fullyetched silicon grating coupler [C]Conference on Lasers ElectroOptics Pacific Rim, 2017.

[46] Wang Z, Liu Y, Wang S, et al. Ultracompact broadb 3dB power splitter based on subwavelength grating at 2μm [C]Optical Fiber Communications Conference Exposition, 2021: 5.

[47] H Xie, Y Liu, W Sun, et al. Inversely designed 1 × 4 power splitter with arbitrary ratios at 2-μm spectral band. IEEE Photonics Journal, 10, 1-6(2018).

[48] E Stanton, N Volet, J Bowers. Silicon arrayed waveguide gratings at 2.0-mum wavelength characterized with an on-chip resonator. Optics Letters, 43, 1135-1138(2018).

[49] Y Liu, Z Li, D Li, et al. Thermo-optic tunable silicon arrayed waveguide grating at 2-μm wavelength band. IEEE Photonics Journal, 12, 1-8(2020).

[50] Y Liu, X Wang, Y Yao, et al. Silicon photonic arrayed waveguide grating with 64 channels for the 2 µm spectral range. Optics Letters, 47, 1186-1189(2022).

[51] H Zhang, M Gleeson, N Ye, et al. Dense WDM transmission at 2 µm enabled by an arrayed waveguide grating. Optics Letters, 40, 3308-3311(2015).

[52] Huang M, Zheng S, Long Y, et al. Experimental demonstration of 2μm onchip twomode division multiplexing using tapered directional couplerbased mode (de) multiplexer [C]Optical Fiber Communications Conference Exposition, 2018: 6.

[53] S Zheng, M Huang, X Cao, et al. Silicon-based four-mode division multiplexing for chip-scale optical data transmission in the 2  μm waveband. Photonics Research, 7, 1030-1035(2019).

[54] Zheng S, Huang M, Cao X, et al. Demonstration of 2 um onchip twomode division multiplexing using tapered directional couplerbased mode (de)multiplexer [C]Conference on Lasers ElectroOptics, 2018: 5.

[55] D Liu, H Wu, D Dai. Silicon multimode waveguide grating filter at 2 μm. Journal of Lightwave Technology, 37, 2217-2222(2019).

[56] L Shen, M Huang, S Zheng, et al. High-performance silicon 2 × 2 thermo-optic switch for the 2 μm wavelength band. IEEE Photonics Journal, 11, 1-6(2019).

[57] Yu T, Liu Y, Li Z, et al. Integrated thermooptic switch f 2 μm spectral b [C]The International Photonics Optoelectronics Meeting, 2019: 4.

[58] J Xu, X Li, Z Qiao, et al. 1×N (N=2, 8) silicon selector switch for prospective technologies at the 2 μm waveband. IEEE Photonics Technology Letters, 32, 1127-1130(2020).

[59] C Zhong, H Ma, C Sun, et al. Fast thermo-optical modulators with doped-silicon heaters operating at 2 μm. Optics Express, 29, 23508-23516(2021).