ARGUMENT 2

PHOTON NOISE MUCH HIGHER THAN THERMAL NOISE AT OPTICAL WAVELENGTHS

Because of quantum noise effects, the noise associated with the statistical arrival of optical photons is much higher than the normal thermal noise in electronic receivers. So optical receivers are far noisier than radio-frequency receivers, and hence far less sensitive.

Counter Argument

This is true. However, it can be shown that the effect of the much high Effective Isotropic Radiated Powers (EIRPs) of optical uplinks is such to so increase the signal strength at the targeted receiver, that it more than makes up for the increased receiver noise. The bottom-line is that the link signal-to-noise ratio (SNR) is far superior.