A fast optical LED pulse generator (at least hundreds of picoseconds rise time)

Thread Starter

LordOfThunder

Joined Jun 27, 2018
32
Hello!
I am a Ph.D. student in particle physics and in our lab we need to calibrate some electronics to measure time with hundreds of picoseconds resolution.
The electronics are meant to be connected to MPPCs (a kind of avalanche photodiode). This is why we use a LED to calibrate them ... anyway, the details of the calibration process may not be relevant here.
What I am asking is: what is the best (but relatively inexpensive) device/circuit to drive a LED with very short rise time?
In an ideal scenario, ~100 ps long LED light pulse is what I am looking for.
If less than some hundreds of euros/dollars we might even consider buying some new device.
I don't know if in any of the following links there is what I am looking for:
  1. Geozondas
  2. Alnair Labs
  3. Picoquant
  4. Edinburgh Instruments
  5. A fast optical LED pulse generator
  6. AVTECH
The LED itself can be any (non-white) commercial LED.
Thank you
 
It appears you have already found sources for the pulse generator. The Alnair Labs EPG-210 device looks like it could do the job. I do not know the price, you will have to check with the manufacturer.
The EPG-210 can do 100pS at +-8pS. The datasheet (attached) has an example of switching laser through a modulator. You would need to do the same kind of operation, I'm certain the LED would not be able to turn on in 100pS.
 

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Thread Starter

LordOfThunder

Joined Jun 27, 2018
32
Thank you to both of you for the links! They are really useful!
The conclusion is that, if I want to emit light pulses in the 100ps range, I need a laser diode (or a particular type of LED called NanoLED) and not an ordinary LED, right?
 
That seems about right although I have not made an exhaustive search. Most LED applications are for human visual indication and the eye can't tell if it takes 1mS or 1uS. I think NanoLED is a trade name so there are bound to be other suppliers with similar products.

If these are too expensive you may be able to build something that will come close. I found a Linear Technology (now part of Analog Devices) application note for a fast pulse generator. It is slower than you require but Analog has a much faster comparator that might work. In the LT app note (AN98f) the pulse generator is described in the section "Micro-mirror Display Pulse Generator". The Analog Device comparator is the ADCMP580. If you are up to it, you may be able to design you own generator. Good luck!
 

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MeSat

Joined May 16, 2019
16
Hello, working on a similar need, not as fast as your requirement but still fast. Problem I have ran into with a LED is the capacitance of the LED and how that affects the switching times. I would go with the laser diode myself to provide a much higher photon count. The fastest pulse I have ever achieved was about 3ns for a standards red LED and it was a very low intensity.
 

Thread Starter

LordOfThunder

Joined Jun 27, 2018
32
@CharlesWMcDonald
Actually, I am not the one who is directly doing the calibration. He is a master student so I cannot ask him to build very complex circuits. That is why I was leaning towards an off-the-shelf solution.
@MeSat
Our equipment is meant to measure very faint signals (tens of photo-electrons), so a low intensity of the LED is not a problem but a requirement!
@sparky 1
Sorry, but I have no idea what you are talking about. Could you please go into further detail?
 
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