  We analyze homodyne detection of macroscopically bright multimode
nonclassical states of light and propose their application in quantum
communication. We observe that the homodyne detection is sensitive to a
mode-matching of the bright light to the highly intense local oscillator.
Unmatched bright modes of light result in additional noise which technically
limits detection of Gaussian entanglement at macroscopic level. When the
mode-matching is sufficient, we show that multimode quantum key distribution
with bright beams is feasible. It finally merges the quantum communication with
classical optical technology of visible beams of light.
