/diy/ - Do It Yourself

Hello, I'm making a thing that needs optocouplers, it's my first time using them. I'm switching it at 1khz to test things but it'll go up to 100khz.
Even without connection to the rest of the circuit the output displays pic related. How do I fix this?
I'm breadboarding it before soldering, maybe it's stray capacitances from the board?