Hi - For my senior project at my university, I'm working on a project where we are sending out a pulse of light with a red laser, and timing how long it takes for the signal to return. Timing the signal is fairly easily accomplished with an Acam TDC-GPX chip which gives us 10ps resolution. We are using a high speed laser driver chip which gives us approximately 40ps rise and fall times on the laser pulse. The issue is in our detector circuit. Looking at traditional photo diodes, they all seem to take in the nanosecond range at a bare minimum to react to an incoming signal. So my question is this: Is it possible to build a circuit that can detect incoming red laser light that will send out a
3.3 or 5V pulse (differential or single ended) in less than a nanosecond? Ideally I'd like to see it in the picosecond range - under 100ps would really be ideal. If there is always the exact same delay (as in a 10ns +- 100ps delay for the output signal) - that would be just fine. We just need the accuracy.If it is possible, can anybody give me some pointers as to how to go about doing this? I should mention that ideally we'd like to keep costs as low as possible, as this is a student project.
Thanks!
-Mike