Couldn't read the transmitted string through laser on the receiver side

Hi all,
I am a beginner to arduino trying to transfer data through LASER in arduino.but I couldn't read the transfered String and i am getting garbage values.I am using photodiode on the receiver side to detect the transmitted signal.I have connected the LASER and photodiode to Tx and Rx of two arduinos respectively.Should I use any modulation algorithms to transfer the data through LASER?? or Can it be transfered simply through Tx without any modulation??? Plz help me out.

Some details and some code, maybe even a schematic might be useful, if you want help.

String doesn't transmit laser light very well (it will transmit sound, if held taut) - try optical fibre.

Transmitting data as light isn't as easy as just hooking a photo-receptor up to the TX line and flashing light at it with a laser. Read this, than go get yourself a USB cable like the rest of us.

Start with a simple sketch that will show you when the phototransistor is receiving light:

const int PTPin = 0;  // RX pin connected to the phototransistor
void setup(){pinMode(PTPin,INPUT);pinMode(13,OUTPUT);}
void loop() {digitalWrite(13,digitalRead(PTPin));}

That will light the onboard LED when the phototransistor pulls the input pin HIGH. Can you get the LED to go on an off when you shine the laser on the phototransistor? If that doesn't work you have no hope of sending data.