Interfacing Arduino Uno with DET025A/M Photodetector from Thorlabs

In my project I had to interface DET025A/M Thorlab Photodetector. So I connected it to one of the analog pins of the Arduino Uno. Turned on the laser(532nm green laser) so that the beam spot is at the center of the photodetector aperture but getting random values on the serial monitor. Uploaded analog input example program having only the sensor read and not the led lighting. Can anyone solve this problem?

Thanks in advance!

You probably forgot to connect the grounds, and you definitely forgot to read the "How to use this forum" post.