Laser diode
![Top: a packaged laser diode shown with a penny for scale. Bottom: the laser diode chip is removed from the above package and placed on the eye of a needle for scale.](/Images/godic/202502/10/Diode_laser0118.jpg")
![](/Images/godic/202502/10/Laser_diode_chip0118.jpg")
![A laser diode with the case cut away. The actual laser diode chip is the small black chip at the front; a photodiode at the back is used to control output power.](/Images/godic/202502/10/Laser_diode_with_the_case_and_window_removed-powered_off0118.jpg")
![SEM (Scanning Electron Microscope) image of a commercial laser diode with its case and window cut away. The anode connection on the right has been accidentally broken by the case cut process.](/Images/godic/202502/10/Laser_diode_with_case_cut_away0118.jpg")
A laser diode, or LD, is an electrically pumped semiconductor laser in which the active laser medium is formed by a p-n junction of a semiconductor diode similar to that found in a light-emitting diode.
The laser diode is the most common type of laser produced with a wide range of uses that include fiber optic communications, barcode readers, laser pointers, CD/DVD/Blu-ray Disc reading and recording, laser printing, laser scanning and increasingly directional lighting sources.