>>3805893laser beams can be modulated
you can even transfer data/information with lasers, the easiest is doing it with sounds/music. you can easily modulate a stream of analogue audio signals on a laser beam using piezo elements and then read out the laser using light receptors
see pic related for an experiment like that.
I suppose for OPs pic they shoot a laser beam at the plant and then read out the reflected laser light particles with some sort of light receptor, which then enabled them to simulate or rather emulate sounds
