Difference Between FP Laser and DFB Laser

In 1953, the Hungarian-American physicist John von Neumann has given the concept of the first semiconductor laser or laser diode and in 1957 the Japanese engineer Jun-ichi Nishizawa patented the world’s first semiconductor laser. But this laser diode is very power inefficient and practically useless.

Since then research has been done across laser diodes for years and today we have lasers like DFB and FP Laser which give us efficient results with low power. These laser diodes generally work on 1310nm and 1550nm wavelengths, although there may be a slight difference in wavelengths.

In this blog, we will learn about DFB and FP Laser with their structure and applications. And in the last, we see a quick comparison of both of these lasers

What is FP Laser?

A Fabry-Perot laser is a type of laser diode abbreviated as FP laser. This is a simple and common type of laser diode which is generally working on 1310nm to 1550nm wavelengths. This laser was named after French scientists Charles Fabri and Alfred Parrot.

The FP laser has a wide spectral width and emits multi-longitudinal mode coherent light, hence this laser is called a multi-longitudinal mode laser. This laser is characterized by its ability to support multiple longitudinal modes due to its broad gain spectrum.

This laser features a Multiple Quantum Well (MQW) active layer structure. The MQW structure includes an active region in the center with two parallel partial mirrors on either side, forming a Fabry-Perot resonator. This arrangement allows for the generation of multiple wavelengths of light within the resonator.

FP lasers are mostly used for short-distance transmission due to their relatively low data rate. These laser diodes operate at a low threshold and current, and they are capable of functioning across a wide range of operational temperatures, which contributes to their versatility in different environments.

Fabry-Perot lasers are employed in various applications, including optical transmission, data communication, and local optical networks, where their broad spectral output and ability to operate over diverse temperature ranges are advantageous.

What is DFB Laser?

Distributed feedback laser is a semiconductor laser diode best known as a DFB laser. However, this laser is also available in the market alongside fiber lasers. But here we will focus on DFB laser with semiconductor laser diodes.

The spectral width of the distributed feedback laser is narrow, so it delivers high output power and emits single-longitudinal mode coherent light, which is why it is referred to as a single-longitudinal mode laser. This characteristic is essential for applications requiring precise wavelength control and stability.

Unlike traditional laser structures, distributed feedback lasers do not use two mirrors on both sides of the active region to create optical cavities. Instead, a diffraction grating is integrated into the active region, acting as a wavelength-selective element and providing feedback with a single mirror. This design eliminates the need for external mirrors and contributes to the laser’s stability.

DFB lasers typically operate at wavelengths of 1310nm and 1550nm, but Inphenix’s lasers cover a broader range from 1310nm to 1660nm. The incorporation of a diffraction grating within the active region enhances the stability of DFB lasers compared to Fabry-Perot (FP) or Distributed Bragg Reflector (DBR) lasers.

These lasers are primarily used for high data rate long-distance transmission and clean single-mode operation due to their high output power and stability. They also provide smooth and tunable wavelength control within extremely narrow spectral widths. Consequently, DFB lasers are employed in optical sensors, fiber optic sensors, metrology, LiDAR, and various spectroscopy applications.

Also See: DFB Laser vs. DBR Laser

FP Laser vs DFB Laser:

Now, let’s know the difference between DFB and FP laser by doing a side-by-side comparison with the table.

We hope that with the help of this post, you are well aware of the difference between FP Laser and DFB Laser. If you want to know more about these two lasers then our blog Overview of FP laser and Everything you need to know about DFB lasers can be useful for you.

Inphenix is a well-known name in the optical product manufacturing industry. We specialize in creating advanced optical components and devices, including various types of lasers and diodes. Our product lineup features swept-source lasers, VCSELs (Vertical-Cavity Surface-Emitting Lasers), LiDAR lasers, superluminescent diodes, and semiconductor optical amplifiers. Our innovations support a range of applications across industries such as telecommunications, automotive, medical, and industrial sensing.