i once tried to build a similar circuit, i found that the laser diode i was trying to use didnt switched for freqs over 10khz, i guess it had a huge capacitance.
at first, i guess it migth work but before commiting to building the circuit you should get a laser diode able to work at the freqs involved.
As i see the laser should be able to perfom well into de 400mhz range.
Well it is unclear how it can interface the RJ plug.
Is it unaware of the tcp/ip or does it leave everything to the network card and it only cares about the physical medium?
Can you make a low speed home network using infrared with this?
It's replacinig the Ethernet cable with the IR signal.
The output (TX) from the Network Interface card is modulating the Oscillator output - the crystal and 74AS04 are the oscillators, and the 74AS08's are the 'modulators'. The IR Diode and it's circuit demodulate the returned signal and drive the input of the Network Interface card (RX).