The output is pretty clean in my experience. I use my photodiode in photoconductive mode (reverse bias), which makes it faster and supposedly noisier but I haven't noticed any noise except in some applications (I note below). The response time seems to be plenty fast in the applications I've used it.

If I were to give a couple suggestions for a similar beambreaker using a photodiode, here's what I would suggest:
  • Use it in photoconductive mode for speed
  • You want a good IR source that's not a constraint on your design, so make sure you're getting a strong output from the IR emitter. I typically use something like 500 ohm resistors for mine, which means I'm pushing about 8mA from 5V (~1.2V fwd voltage for the diode). You can go higher, but 500 ohms seems to work for me. Fun fact: you can make sure they're working (or not burned out) by using your cell phone camera, which is filtered for human vision but some near IR gets through and shows up as a hazy purple aura around the LEDs.
  • I'd recommend using a potentiometer to ground on the output of the photodiode unless you've already played around with it and know what resistance you need. Getting the voltage low enough to trigger low when it's not exposed, and then high enough to trigger high when it is exposed can take some tweaking. A resistance range on the order of 2k-10k seems to work for me most of the time.
  • Distance between the photodiode and emitter is a big factor. In my applications, they are typically 1" to 6" apart. So take my suggestions with a grain of salt depending on how far your photodiode is from your emitter.
  • If you're photodiode is anywhere near a motor, then shield the wires, make them twisted pairs, put a faraday cage around the motor, and/or verbally threaten the motor. A powered motor will create a lot of EMI that the wires from the photodiode can pick up and will generate a LOT of noise and false high/low triggers. I made an inertial dynamometer to test some motors for drones, and data from some of the larger motors were initially unusable. Making the wires as short as possible, twisting them, wrapping the wires in foil, adding distance between the motor and photodiode wires, and changing the orientation of the motor with respect to the wires fixed it for me.

Hope that helps!
Dave