I do not know exactly where it is wrong. I tried directly to connect the pin to 5V but not start the laser.
Arduino I have no time to check that communication is good.
I have found that Arduino pin 10 receives signal LR4 Tx.
For now I'd settle for that arrancase laser.
The wiring looks okay to me. Testing serial voltage is easy. When not sending, the line is HIGH. Just meter the voltage between LR4 RX and ground. I would use larger value resistors for the divider just to draw less current but that is me. 10k is not too much.
Do you want the laser for range finding or just to have a laser?
I bought a bag of these thinking they were just the diodes. Then I bought another bag when I found they are diode, optics and constant current circuit able to run on 5V. They won't pull more than 20mA, safe for Arduino pins.
No, I haven't run a test to find the lifetime of one. At 46 cents each, I got extras.