Last issue mentioned that DFB laser diode is widely used in daily life, so do you know where it is mainly used? Let's take a look at it together.

phototelegraphy

DFB is almost one of the soul components of optical communication system. We often say that CWDM and DWDM wavelength division multiplexing systems rely on DFB lasers with different wavelengths to transmit data from different channels. Because its wavelength is very stable, it is not easy to drift and will not cause channel crosstalk.

Gas detection

Nowadays, many environmental protection equipment and industrial safety monitoring use DFB lasers as light sources, such as detecting methane, carbon dioxide and carbon monoxide. The principle is actually very simple: different gases will absorb light at a certain wavelength, and DFB laser can accurately emit that wavelength, and judge the gas concentration by detecting the change of absorption.

Optical fiber sensing

This sensing system is used in many high-end occasions, such as bridge monitoring, oil well temperature measurement and even railway track safety detection. DFB laser is responsible for providing stable narrow linewidth light source in this kind of system, and measuring stress or temperature by using the reflection change of light in optical fiber. Its narrow line width and good coherence make the signal have higher resolution and more accurate measurement.

Of course, DFB lasers are not cheap, and the temperature control requirements are high, so they are generally not used in consumer products. However, it is almost standard in those industries that require high "stability" and "accuracy".

Generally speaking, the most prominent characteristics of DFB laser diode are single longitudinal mode output, stable wavelength and narrow line width, which makes it the core light source in high-end fields such as optical communication, gas detection and optical fiber sensing.