Components of Diode Laser

      
 

The nomenclature distinguishes between unmounted and mounted laser diode bars.

From the functional point of view, the unmounted laser diode bar (1) is a light-emitting diode.

With one exception it meets all technical requirements to be operated as a laser : In unmounted

state, no loss power can be dissipated. In this state, operation of the laser diode bar is not

possible.

 

The ready-made diode laser module, however, can be considered to be a radiation source in

 

the sense of a ready-for-use component.

 

In different contexts, diode lasers of above 1W or above 10W are termed as high-power diode

 

laser (HDL).

 
 

In this document, the term HDL is used for diode lasers based on laser diode bars.

 

Unlike the single chips customarily used in the field of telecommunications, so-called

laser diode bars are used exclusively.

This refers to all products and usually conicides with the power limit above 10W.

In the following, the terms high-power diode laser (HDL) and diode laser (DL) are used

synonymously.

 

Operating principle of a Laser Diode

 

On a laser diode, the p-n junction between two strongly doped n- and p-materials represents

the active medium / PEUSCH/. When applying a forward voltage approximately corresponding

the band gap at the p-n junction, electrons and holes are being injected above the p-n juction.

The narrow zone in which this inversion is generated is called the active zone. If the forward

voltage is raised above the threshold voltage and appropriate semiconductor materials are used,

e.g. GaAs, the probability for a radiating recombination is high. If there is a sufficiently high

concentration of injected charge carriers, this will result in an optical amplification.

The crystalline end faces of the semiconductor form the mirrors of the resonator.

Diode lasers exhibit a very high electro-optical efficiency of nel.-opt. = 50%.

Typically, commerecially available wavelengths are 808nm, 940nm and 980nm.