Fast, efficient IR LEDs?

Phil Hobbs · 2010-02-05T16:56:15+00:00

I need a fast IR LED (> 20 MHz, < 50 pF) for an optical feedback gizmo. I have some Stanley DN310s, but they've been discontinued. Other possibilities are:Vishay TSFF5410 -- 870 nm, 0.% W/A typ 15 ns rise/fall, 125 pF typVishay VSLB3940 -- 940 nm, 0.4 W/A typ 15 ns rise/fall, 70 pF typPanasonic LNA4905L -- 880 nm, 0.3 W/A min 30 MHz typ, no other specsOsram SFH4550 -- 850 nm, 0.5 W/A typ 12 ns rise/fall, no C specIt would be really nice to find something with a flat front facet and (especially) lower capacitance, because it has to work at quite low currents (5-10 uA).Any suggestions?ThanksPhil HobbsPS: Amazing how we're actually talking about electronics at the moment!-- Dr Philip C D HobbsPrincipalElectroOptical Innovations55 Orchard RdBriarcliff Manor NY 10510845-480-2058hobbs at electrooptical dot net

Feb 05, 2010 64 Replies

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John Larkin 16 years ago

Photomultiplier tube, avalanche photodiode, or microchannel plate. The problem with all three is background "false positive" rate; the PMT is probably best. Cooled detectors can have very low background rates.

John

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John Larkin 16 years ago

These are nice:

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Osram makes very nice stuff. The 206K is really a beautiful part.

John

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Martin Brown 16 years ago

First generation image photon counting systems date back to the early

80's and used an image intensifier and a centroid measurement of the spot. They are still in use for certain type of astronomy. eg.

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Modern ones have lower noise, higher count rates, better linearity etc.

Similar methods are used to count individual ions in mass spectrometry.

Regards, Martin Brown

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Phil Hobbs 16 years ago

Yes, in theory. In fact, diode lasers are efficient enough that in certain circumstances you can make squeezed light by putting a sub-Poissonian bias current into the diode.

Squeezing means changing the quantum uncertainty distribution from circular, i.e. equal in sine and cosine phases and uncorrelated, to some other shape while still preserving the uncertainty product a la Heisenberg. In this case, you get more phase uncertainty and less intensity uncertainty.

That suggests that under some circumstances there is a measurable correlation between terminal voltage at the diode and photon emission. There are folks on sci.optics who would be able to give a better answer, though.

Cheers

Phil Hobbs

Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 email: hobbs at electrooptical dot net http://electrooptical.net

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