  This paper considers the effects of gravitational induced uncertainty on some
well-known quantum optics issues. First we will show that gravitational effects
at quantum level destroy the notion of harmonic oscillations. Then it will be
shown that, although it is possible(at least in principle) to have complete
coherency and vanishing broadening in usual quantum optics, gravitational
induced uncertainty destroys complete coherency and it is impossible to have a
monochromatic ray. We will show that there is an additional wave packet
broadening due to quantum gravitational effects.
