Free space optics (FSO) can be used as an alternative to the currently used wireless radio communication systems to meet the increasing demands for the uninterrupted internet connection in High-Speed Trains (HSTs). FSO is less prone to interference, license-free and more secure as compared to Radio Frequency (RF) technology. In this paper, we have compared three different wavelengths (850, 1330, and 1550 nm) for the dual-wavelength model at a bit rate of 10 Gb/s to see which two wavelengths provide better results. The system is studied for return to zero (RZ) and non-return to zero (NRZ) modulation formats this electronic document is a “live” template and already defines the components of your paper [title, text, heads, etc.] in its style sheet.