Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers

LPF Donation via Stripe | LPF Donation - Other Methods

Links below open in new window

ArcticMyst Security by Avery

on/off cycle limit for VCSELs, 100's MHz possible?

Joined
Sep 19, 2013
Messages
3
Points
0
Assuming a suitable drive circuit,

Is it physically possible to pulse VCSELs or other diodes to microWatt power at an on/off "pulse" rate of for instance 500 MegaHertz or faster?

Will I encounter problems of quantum tunnelling?
 





Joined
Jan 14, 2011
Messages
3,816
Points
63
I think you should be able to... purpose-built laser diode drivers can usually do >1Gbps, so I'd think >1GHz is possible.
 
Joined
Sep 19, 2013
Messages
3
Points
0
Excuse me, but I must also introduce three caveats:

1. the VCSELs are in the visible spectrum

2. they are regular production units and not created for telecommunications (high performance)

3. the VCSELs' on state must have an exact output intensity which can be any one of at least 256 discrete levels in a range from 1 to 16 microWatts.
 
Joined
Jan 14, 2011
Messages
3,816
Points
63
But I would suppose that regular laser diodes (not VCSELs) should be able to do this, no?
 

SKeeZ

0
Joined
Sep 2, 2013
Messages
463
Points
28
i don't think so, VC SELs are specialized for this and i think this application requires more precision than would be possible by a laser diode (keeping fluctuation within 1/16 of a microwatt or less and modulating it over 256 level with 1-16 microwatts is incredibly precise). i think using a VCSEL is a better plan of attack. I also don't know if there are production units easily available for the application. (correct me if im wrong or if i have no idea what im talking about)
 
Last edited:
Joined
Sep 19, 2013
Messages
3
Points
0
I would agree that VCSELs are best.

The difficulty for me lies in the fact that of the 40 to 50 suppliers I have contacted, they do not seem to understand issues like:

thermal expansion and contraction

output power as a function of current and temperature induced resistance

average and peak power

uniformity of production unit characteristics

light emittance (if any) below lasing threshold

modulation across the lasing threshold instead of only above it


and so on...
 

SKeeZ

0
Joined
Sep 2, 2013
Messages
463
Points
28
In my opinion, there is virtually no way to keep modulation that specific with a diode. and to calibrate a diode & driver pair to the accuracy necessary for this application would be very expensive.
 




Top