Re: help: Demodulator design
Since it appears that you have a strong signal and low speed needs, simple circuits will work.
Start with a detector type. This can produce a voltage output when the laser puts photons into it. Follow this by an op amp circuit to give you gain. Follow this by a circuit that determines if the modulation is there. A simple high pass filter should work. Follow this by a rectification op amp circuit and then by a comparator.
You can simulate the circuit in spice or use a plug in board to make a trial circuit.