LASER Diode – How it Works

Laser is of prime importance in Optical memories, Fiber optic communications, Military applications, Surgical procedures, CD players, Printers etc. Various forms of lasers like Gallium Arsenide laser, Helium Neon laser, Carbon dioxide laser etc are used in various applications. CD players use laser technology to read the optically recorded data in the form of Bits and Pits on the CD.

Laser is a narrow beam of Photons emitted by specially made laser diodes. Laser diode is similar to an ordinary LED, but it generates a beam of high intensity light. A laser is a device in which a number of atoms vibrate to produce a beam of radiation in which all the waves have single wavelength and are in Phase with each other.

Monochromatic Laser

laser beam

Laser light is Monochromatic and can be focused as a pencil beam The beam of a typical laser has 4×0.6mm widening at a distance of 15 meters. Like an LED, laser diode converts electrical energy into light energy.

laser gun

How it Works?

The most common laser diode generates semiconductor or injection laser. In these lasers, a population of Inversion Electrons is produced by applying a voltage across its p-n junction. Laser beam is then available from the semiconductor region. The p-n junction of laser diode has polished ends so that, the emitted photons reflect back and forth and creates more electron-hole pairs. The photons thus generated will be in phase with the previous photons. This will give a Pencil Beam and all the photons in the beam are Coherent and in phase.

laser emission

Applications of Laser

Laser diodes can be switched on and off at frequencies as high as 1GHz, making them ideal in Telecommunication applications. Since laser generates heat on hitting the body tissue, it is an ideal solution to heal sensitive parts like Retina of Eye and brain. Laser can be used to pinpoint the lesions so that nearby tissues are not affected as in the case of surgery.

Laser Diode

laser diode

A Word of Caution

Laser is a high intensity penetrating beam and is extremely dangerous when focused on to the Eye. Low cost Laser pointers are now available in the market and some people handle them carelessly and may even give to children to play with. A Laser pointer with output power higher than 5 mW is harmful. Take utmost care while handling laser diodes. Always take precautionary measures while trouble shooting CD players, Laser printers etc.


Join the conversation!

Error! Please fill all fields.


    • Idiotpointer

      Maybe you should allow yourself to wait complaining about grammar until you have learnt how to spell?

  • El Master

    Unfortunately, due to the Chinese and their desire to ignore safety in the name of making money, the UK and many other countries have lasers in the hands of the public which far exceed the legal limit for power output put in place to protect the stupid or uninitiated. My idiotic neighbour has one he purchased on the Internet which is over 100mW and he shines it at people with no thought of potential eye damage. He seems to think that although very bright, it couldn’t possibly cause blindness since it was sold to the public. I also think he believes one must stare at the beam for a while to be damaged, not realising a split-second exposure can destroy the retina.

    An amazing invention completely and utterly disrespected and abused. Should never have been made available to the public.


      Some years ago about 15 years these were sold as pointers when doing slide shows I then contacted the importer and warned them that they can be made responsible for this and since then these were not so freely available. There was a vacuumhead that did shine it onto airplanes that came in to land at international airport and the pilots did complained about it and the rascal was severely punished


    Excellent teaching wish I had some of this 50 years ago!! Interesting way explained


    The page is clear and easy understood nice one

  • cjoann51

    do you have any simple circuit for laser based intruder alarm?

  • Syed Shiyas

    Please add a simple laser diode application circuit too.
    Thank you.

Looking for the latest from TI?