Optoelectronic devices what rms linewidth means?

[Cerkit]

Can someone explain to me in the context of optoelectronic devices what rms linewidth means?? For example the rms linewidth of a particular laser is 0.1nm. What does that mean? and what implications does this have on a communications system using that laser?

Thanks

 

[f95toli]

Real lasers aren't perfect, meaning if you take a closer look at a laser which emits light with a nominal wavelength of say 670nm (laser pointer) you will find that it really emits light in a small range, say from 669.95 to670.05 nm; this means that its linewidth is 0.1 nm.

 

[burochokkotti]

lovely explanation, dude :-D just the thing!