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.
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.
FP laser has wide spectral width and emits multi-longitudinal mode coherent light hence this laser is called a multi-longitudinal mode laser.
This Laser has a Multiple Quantum Well (MQW) active layer structure. This structure has an active region in the center with two parallel partial mirrors on either side. This is also called a Fabry-Perot resonator.
FP laser is mostly used for short-distance transmission because of its low data rate. This laser diode works on a low threshold and operating current and also can work in many different operational temperature ranges.
Fabry-Perot laser is used in many applications such as optical transmission, data communication and the local optical network.
Distributed feedback laser is a semiconductor lasers diode best known as DFB laser. However, this laser is also available in the market along with fiber lasers. But here we will learn about DFB laser with semiconductor lasers diode.
The spectral width of the distributed feedback laser is narrow so it gives high output power and emits single-longitudinal mode coherent light hence this laser is called a single-longitudinal mode laser.
Unlike traditional laser structures, distributed feedback lasers do not use two mirrors on both sides of the active region to create optical cavities. But instead, a diffraction grating is used on the active region which acts as a wavelength selective element and provides feedback with one mirror.
Mostly, DFB lasers use 1310nm and 1550nm wavelengths but inphenix’s laser use wavelengths of 1310nm to 1660nm. In this laser, a diffraction grating is involved with the active region of the laser. Because of this, the distributed feedback laser is much more stable than FP or DBR lasers.
This laser is mostly used for high data rate long-distance transmission and clean single-mode operation because of its high output power and stability. Also, this laser provides smooth and tunable control wavelengths in extremely narrow spectral widths. Therefore, DFB laser is used in Optic sensors, Fiber optic sensors, Metrology, LiDAR and different spectroscopy applications.
Also See: DFB Laser vs. DBR Laser
Now, let’s know the difference between DFB and FP laser by doing a side-by-side comparison with the table.
| | |
| Fabry-Perot laser has a generally wide spectral width. | Distributed feedback laser has a generally narrow spectral width. |
| It emits multi-longitudinal mode coherent light. | It emits single-longitudinal mode coherent light. |
| It is mostly used for low-rate and short-distance transmission. | It is mostly used for high-rate and medium-long-distance transmission. |
| The transmission distance of the FP laser is usually within 20 km. (Except gigabit 40km optical modules for FP devices) | The transmission distance of the DFB laser is usually above 40 km. |
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 manufacture different types of lasers and diodes such as swept source laser, VCSEL, lidar laser, superluminescent diodes and semiconductor optical amplifiers.
