How to Drive a Laser Diode

Written by j.t. barett
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How to Drive a Laser Diode
A DC power supply will drive a laser diode. (laser battle image by Yali Shi from

A laser diode is a solid-state electronic device that produces laser light. It is smaller, less expensive and more rugged than an equivalent gas laser, and you can drive it with a regulated direct current, or DC, power supply. As with other solid-state parts, you can destroy a diode with excessive current or voltage, so have the laser diode's data sheet handy and pay attention to its maximum current and voltage ratings.

Skill level:

Things you need

  • DC power supply with current limiting
  • 2 foot banana cables with alligator clips
  • Laser diode
  • Laser diode data sheet

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  1. 1

    Examine the laser diode's data sheet. Find the diode's maximum current and voltage ratings. Note the diode's minimum operating voltage. Also note which of the diode's wires is the cathode and which is the anode.

  2. 2

    Turn the power supply on. Turn the voltage control knob all the way down. Set the current limit to just under the diode's maximum current rating. Plug a banana cable into the power supply's ground connection and clip its other end to the diode's cathode. Plug a second banana cable into the power supply's positive output connection and clip its other end to the diode's anode.

  3. 3

    Turn the power supply's voltage knob up slowly until you reach the laser diode's minimum operating voltage. The laser should begin to shine. Continue turning the voltage up until it is midway between the diode's minimum and maximum values. On the power supply, note the diode's current consumption.

Tips and warnings

  • If the laser diode's wavelength is greater than 750 nanomenters (nm), its light is infrared and you will not be able to see it. Select a laser diode having a wavelength of between 400 and 750 nanometres.
  • Use only laser diodes with rated power of under 1 milliwatt. Always aim the laser away from your eyes.

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