help: Demodulator design

I need to make a demodulator for a modulated laser beam.It would be a simple detector that detects the modulated laser and turns a relay on.

Where shall i begin from?I don't have a strong electronics background..I'm a Computer engineering student. :(

Thanking you

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.