Hello Umer,
I would also like to mention that semiconductor laser , for instance VCSEL array has been proposed as a concept of a compact FSO communications terminal thanks to their high reliability and high-speed modulation (2.5 Gb/s) under high optical power operation (Advanced Free Space Optics (FSO))
also some attractive features of semiconductor lasers, for instance the chaotic dynamics with and without an external perturbation make them an attractive devices and have become widely use in FSO system.Most commonly used lasers in today’s commercial FSO products are:
– Edge Emitting Lasers
– VCSEL
VCSEL is easier to modulate, but generally much lower in power, which limits link budgets, beamwidths and useful operational distances.
This is why most successful long range FSO devices use edge emitting lasers.
There are also some novel types of lasers considered including VECSEL, which we collaborated on two recent projects which were aimed to develop the actual devices.
I hope it will be of some help to you.
Regards
Burhan