Implement Visible Light communication using Arduino I want to implement a simple VLC based communication system using two Arduinos and send messages/data/files between two PCs. For that I have a simple transmitter circuit with an LED on Tx side and a photo-transistor on the receiver side. The codes im using for transmission and reception are attached below, also the circuit image is attached below, but im unable to bring about any communication between the two PCs, the transmitter side works fine as the LED flickers indicating data is being transferred, but its not being received by the photo transistor. I don't know what im doing wrong. Any help would be appreciated, I am doing this as a part of my academics.
Transmitter Code :

void setup()
{
  pinMode(9, OUTPUT);
  pinMode(10, OUTPUT);

  // Clear Timer on Compare Match (CTC) Mode
  bitWrite(TCCR1A, WGM10, 0);
  bitWrite(TCCR1A, WGM11, 0);
  bitWrite(TCCR1B, WGM12, 1);
  bitWrite(TCCR1B, WGM13, 0);

  // Toggle OC1A and OC1B on Compare Match.
  bitWrite(TCCR1A, COM1A0, 1);
  bitWrite(TCCR1A, COM1A1, 0);
  bitWrite(TCCR1A, COM1B0, 1);
  bitWrite(TCCR1A, COM1B1, 0);

  // No prescaling
  bitWrite(TCCR1B, CS10, 1);
  bitWrite(TCCR1B, CS11, 0);
  bitWrite(TCCR1B, CS12, 0);

  OCR1A = 210;
  OCR1B = 210;


  Serial.begin(2400);
}

void loop()
{
  Serial.println("testing testing testing");
  delay(500);
}


Receiver Code: 

void setup()
{
  Serial.begin(2400);
  pinMode(13, OUTPUT);
}

void loop()
{
  // if incoming serial
  if (Serial.available()) {
    readSerial();
    digitalWrite(13, HIGH);
  } 
  else {
    digitalWrite(13, LOW);
  }
  delay(500);
} 
void readSerial() {
  char val = Serial.read();
  Serial.print(val);
}


the transmitter works fine, but the receiver is not receiving anything, I don't know what i'm doing wrong.
The amplitude of the signal at the photodetector is small. Better use ADC for reading.