Laser data transmit: how to

[xnihilo]

I have a laser fence that uses a photo diode/photo transistor. The only problem is shielding from ambient light. But I am not modulating either, just a make / break setup. Modulating should help.

Hello,

Yes, this is a good start.
I may use a LDR. The receptor should be optimized for the wavelength of the laser. I could not find any relevant info on the web, quite surprising...
It should be fairly simple to replace an IR led / IR receiver by the laser equivalent...