On Sat, 30 Mar 2013 10:00:08 -0800 David McQuate <mcqu...@sonic.net> wrote:
> You'll need a photodiode that can detect photons at your lasers' > wavelength. Yes, of course. > You may be able to use a photodiode at a shorter than its > design wavelength as long as there are not coatings (eg anti-reflection) > that block the wavelength of interest. The 1um photodiodes i had a look at, have all a very steep roll of above below 900nm, leading to 0 detection at 800nm. > You'll need to make sure that > both lasers illuminate the same photodiode area, or you won't get a > signal at the difference frequency. Yes. The current plan is to have the beams aligned on the same path. > The difference frequency power > level is generally pretty low, so operating above the photodiode > bandwidth is difficult. My work was at HP and Agilent, who manufactured > the photodiodes we used. Hmm.. that makes it sound more difficult than i anticipated. Any ballpark numbers i can expect? > The photodiode frequency response is primarily limited by the depletion > region's capacitance. The circuit model is simply a current source > shunted by a capacitor (perhaps with bond wire inductance to the RF > connector) so the RF output current falls with increasing signal > frequency. So, i can expect it to behave like a first order filter and assume about 20dB/decade? Attila Kinali -- The people on 4chan are like brilliant psychologists who also happen to be insane and gross. -- unknown _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.