The datasheets to SFH250(photodiode) and SFH757(emitter) give different values for the peak wavelengths. Emission and detection peaks are at 660 and 850 nm resp. What's the reason for that?
LED/DETECTOR with different peak wavelengths
Apr 03, 2019
6 Replies
How about a link to the data sheets or something? GH
It's not easy to tune PD sensitivity peaks, is it? The detector has 75% relative sensitivity at 660nm. OK, unless you have interferring signals at 850nm?
Thanks,
- Win
sorry a typo. it's SFH756.
..Actually they both exist and are very similar...
OK got it. Well you pick the LED for the wavelength you want. For the photodiodes the peak sensitivity is mostly set by the band gap of silicon and ends up near 1 um. They make 'blue enhanced' photodiodes, but they just give a bit more response in the blue.
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And the peak is still ~900 nm.
George H.
Physics. Detector is Si, emitter is GaAlAs (or some alloy in the family).
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design Website:
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