Laser Diode

A laser diode is an electrically pumped laser light that is an active medium formed by p-n junction in a semiconductor diode. It is also called as injection laser diode and the technology is similar to that found in LED. The laser diode is similar to LED in many ways, but it produces a high-intensity narrow beam.

It is one of the most common types of laser used in a variety of products including fibre optic communications, laser pointers, disk reader and recording, barcode reader, laser scanning, printing and directional light sources.

Major Categories of Laser Diode

  • Distributed feedback laser diode
  • Quantum cascade laser diode
  • External cavity laser diode
  • Separate confinement heterostructure laser diode
  • Double heterostructure laser diode
  • Quantum well laser diode.

Characteristics of Laser Diode

The laser diode is characterized as follows:

  • Monochromatic: An insubstantial width of radiated narrow light containing only single color.
  • Well directed: In this type, the light is will be directed in a narrow beam. It is easy to launch through an optical fibre.
  • Coherent: A light with single wavelength emitted by LED with wide wavelength.

Laser Diode

  • The important characteristic of a laser diode is its approach or the threshold. The laser diode doesn’t operate until a minimum power is applied. If the light is below its energy, then the emission is weaker than the threshold compared to the full energy.


Laser Diode has its applications in the field of Telecommunication. One of the core reasons is that it can be modulated and coupled easily as light sources used for fibre optic communications.  It is served as optical parametric oscillators.

Practise This Question

A particle 'm' starts with zero velocity along a line y = 4d. (Where d is a constant). The position of particle 'm' varies as x = A sin ωt. At ωt = π2, its angular momentum with respect to the origin is?