Silicon Photonics Beyond 1.31/1.55 μm: Expanding Applications and Material Limitations

In recent times, there has been a significant interest in advancing silicon photonics beyond the range of 1.31/1.55 μm. This development is driven by its potential applications in various fields such as optical communication, nonlinear photonics, lidar, and optical bio-sensing. For instance, certain bio-molecules and gases like glucose, CH4, CO2, and CO exhibit strong overtone and combination absorption lines in the wavelength range of 2-3 µm. However, conventional semiconductor materials like Ge and InP, which are widely used, are limited in terms of their cut-off wavelength for light absorption due to their fixed bandgap, thereby impeding their adaptability.