I'm working on a project using 2 Arduinos connected to 2 computers to demo Serial to Serial communication.

We're using Arduino Uno connected to the computer via Serial and software serial for inter-Arduino communication. We used wires to connect software serial RX & TX lines, but we'd like to connect these pins to a laser transmitter and receiver.

We're trying to show wireless communication using an optical medium, which is why we wanted to use a Laser transmitter and receiver.

We're trying something like the setup in this YouTube video $3 laser transmits audio over 100m (Arduino)

Any idea how high a baud rate we will be able to achieve using the transmitter and receiver?

Receiver: Laser Sensor Module non-modulator Tube Laser Receiver

Transmitter: 5V ... Board For Arduino AVR ... KY-008 Laser Transmitter

  • 1
    you can use a red or ir led to receive, or a phototransistor, all of which should give dozens of KHz.
    – dandavis
    Mar 17, 2017 at 16:47
  • Speed is likely to be limited by use of software serial instead of the laser link. You might consider using Mega2560's (which have 4 UARTs) instead of Uno's Mar 17, 2017 at 18:35
  • This particular receiver module is advertised as being "non-modulated" which means it is just a digital on/off indicator. I can't find info on the latency in the circuit before it determines whether or not it can find the laser signal, so presume the speed will be very very slow. You would be better off using just a LDR or something else other than this module.
    – SDsolar
    Mar 17, 2017 at 22:33
  • @dandavis I tried feeding a square wave to an IR LED. I hooked up a photodiode (and resistor) to an oscilloscope. The rise times became too slow above 2kHz.
    – Carl
    Mar 18, 2017 at 5:22
  • hook the LED to the oscilloscope (w/o resistor), and shine a laser into the led. you should get up to the forward voltage an a few microamps of current. "waterclear" LEDs work a lot better than diffused.many in series adds voltage; i used 3 flat ones in series as an opto-isolated mosfet driver (K-d, A-g, 10Mohm s-g).
    – dandavis
    Mar 18, 2017 at 9:18

1 Answer 1


Any idea how high a baud rate we will be able to achieve using the transmitter and receiver?

Looks like the receiver module has a low-pass filter. That could reduce the baud-rate depending on the RC-factor (10 Kohm * 10 nF gives a cut-off frequency of 1.6 kHz). I would recommend checking the actual components. The above is a guesstimate.


  • 1
    Possible. But the capacitor is connected across the supply terminals of the component, not the signal (I'm too sure about filters, just guessing). Wouldn't the capacitor need to be connected between signal and ground (with a series resistor) for it to be a filter? A person on Youtube used this sensor with a 115200 baud rate, but I'm not sure about the error rate he encountered.
    – Carl
    Mar 17, 2017 at 15:22

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