20 February 2018

Types of laser

Before we learn about types of LASER first let we understand what is full form of LASER. Here this article gives information about different types of laser mode to know more details about LASER in optical communication devices.

Single-Mode Lasers :

Single-mode lasers are preferred for high-speed long-distance communications. The single mode lasers that contain only a ( single longitudinal mode and a single transverse mode). Therefore, the spectral width of the optical emission is very narrow for this mode.

To restrict laser only for one longitudinal mode, its length of the lasing cavity is reduced such that only a single longitudinal mode falls within the gain-bandwidth of a device. Because of this device becomes hard to handle and output power is limited to a few mill watts only.

Modulation of Laser Diodes :

Imposing information on light stream is called as modulation of a laser diode.

Imposing information on light stream is called as (modulation of laser diode The / produce a varying optical power or by using an external modulator to modify optical power.

The limitation of the direct modulating rate of laser diodes depends on spontaneous (radiative) and stimulated carrier lifetimes and the photon lifetime

Spontaneous lifetime :

It is a function semiconductor band type structure and the concentration.

Stimulated carrier lifetime :

It is a function of optical density in the lasing cavity and it is typically 10 ps.

Photon lifetime :

In this laser average time that the photon resides in the lasing cavity before being lost by absorption.