Review on optical nonlinearity of group-IV semiconducting materials for all-optical processing

Group-IV semiconductor compounds with intense optical nonlinearity have emerged as a new branch of all-optical processing materials benefiting from the manufacturing compatibility with silicon electronic and photonic integrated circuits. Due to the chemical reforming on the bonding or precipitating feature of the compositional atoms in the membrane matrix, either the orbital hybridization or the quantum self-assembly of interstitial composites can be employed to reform the electronic and optical characteristics. The recent development on enhancing the nonlinear refractive indices of the group-IV semiconductor materials has revealed significant progress to accelerate the all-optical switching logic, which greatly reduces the energy consumption to enable the constitution of the advanced multi-logic gating and the entry-level photonic computing circuits. This work not only overviews the group-IV semiconductor photonic data processing elements but also prospects for the future direction of optical quantum computation and communication. To date, the nonlinear refractive indices of the group-IV semiconductor materials can be obtained as 10(-8) to 10(-16) cm(2)/W in the range between 300 and 10 000 nm in 2022. The wavelength conversion and data switching with bit rate beyond 25 Gbps have been achieved via nonlinear photonic waveguide components. By taking the non-stoichiometric SiC-made micro-ring waveguide as an example, the n(2) as high as 3.05 x 10(-14) cm(2)/W of the resonant SiC micro-ring gate is retrieved from the pump-probe analysis. The eye-diagram of the wavelength converted data in the micro-ring achieves its signal-to-noise and on/off-extinction ratios (SNR and ER) of 5.6 and 11.8 dB, while up to 25-Gbps all-optical data-format inversion with 4.8-dB SNR and 10.2-dB ER is also performed during an ultrafast switching within rising and falling time of less than 22 ps. Such all-optical data processing including both wavelength switching and format conversion in the highly nonlinear optical SiC waveguide resonator can achieve error-free operation with corresponding bit-error-ratios of lower than 1 x 10(-5) at 25 Gbps after forward error correction. (C) 2022 Author(s).All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY)license (http://creativecommons.org/licenses/by/4.0/).