Differences between DBR & DFB Lasers

DBR and DFB lasers are the two most familiar and most used lasers with high power single frequency. Both of these lasers have distinct applications in various industries. The high efficiency and exceptional spectral purity enable them to be used in multiple scientific instruments.

This article discussed everything about laser diodes- from the definition, types to characteristics. Further, we have also explained the difference between DRB and DFB lasers in the later section. Let us begin with what is a laser diode.

What is Laser Diode?

A laser diode can be defined as the semiconductor device that generates high-intensity coherent light by converting electrical current into light, where, the word LASER stands for Light Amplification by Stimulated Emission of Radiation.

All of the lasers, including the DFB laser, generate a very sharp and narrow beam of light, which is used in many technologies and industries such as laser printers, DNA sequencing instruments, laser surgery, optical communication, and skin treatment, among others.

Types of Laser Diodes

We can classify the laser diodes into four principally different types, namely,

Double heterostructure laser diodes
Quantum well laser diode
Separate confinement heterostructure laser diodes, and
Vertical cavity surface-emitting laser diode
Along with these, there are many other sub-types of laser diodes too. Such as,

  1. Distributed Feedback Laser Diode- also known as DFB laser

Distributed Bragg Reflector Laser Diode also known as DBR laser
Quantum Cascade Laser Diode
External Cavity Diode Laser,
Vertical External Cavity Surface Emitting Laser Diode (VCSEL), and
Interband Cascade Laser Diode

It is to be noted that each of these lasers is used based on its characteristics, and it has different applications. For example, DFB lasers are used in communication and clinical applications because of its smooth control of wavelength and narrow spectral width. At the same time, VCSEL are used in various laser-based products such as face ID, laser printers, smart glasses, and biomedical sensing.

Characteristics of Laser Diodes

Almost all the laser diodes, including DFB laser and VCSE laser, have the following five characteristics.

Directionality: The laser beam emits highly directional light, having almost zero laser divergence.
Monochromaticity: The laser light is nearly monochromatic in nature.
Coherence: Laser is highly coherent. Indeed, it is the main characteristic of the laser that distinguishes it from other light sources.
Intensity: Compared to other light sources, laser beams are highly intense. Its power is concentrated in a tiny diameter beam.
Brightness: Due to the continuous reflections, laser light produces a beam of high intensity as well as brightness.
DFB Laser Vs DBR Laser

Although there are many similarities between DRB and DFB lasers, there are many differences too. Such as,

Both of these lasers have a different grating location. The DRB uses high reflectivity surface grating, whereas the DFB laser uses low reflectivity surface grating. Another significant difference between these two lasers is the mode of selection. DFB lasers operate with two modes while DBR laser operates only at the single longitudinal mode.

We hope these points and information have cleared all your doubts and confusion related to the laser diode. These details may have also helped you to clarify how DBR and DFB lasers are different.