[Laser] Pulse Density Modulation

[TWOSIG at aol.com]

I have been reading about PDM, pulse density modulation.  It seems to  be 
something that can be readily adapted to light communication for light  emission 
devices that are non-linear, like gas discharge tubes and lasers.  
 
Has anyone thought of using it?
 
Do typical sound cards use PDM to generate the audio output?  If so,  what is 
the pulse rate, can the rate be adjusted under software control, and is  the 
pulse stream readily accessible.  I was thinking that interfacing the  pulse 
stream to drive a light emitter might be easier than interfacing the  analog 
audio output with an outboard modulator.
 
 
James
N5GUI