Distributed Feedback Lasers
These devices are characterized by temperature stability of the oscillation frequency. The temperature depending upon coefficient of the wavelength in a typical device is 0.1nm /deg. It is determined by the temperature dependency on the refractive index. This make the possibility for tune the radiation frequency by adding a temperature control unit on the laser. The designing of these devices are simple and it is very significant for tunable DFB devices.
Traditional type of devices has antireflection coating on one side of the cavity. Coated side is for high reflectivity on the other side (AR/HR). These lasers generally have higher output power as they taken light from the other side. The HR side prevents lost of power from the other side. Many times the laser HR facet forms at the crest of the grating and the optical mode. It depends upon phase of the grating and the optical mode, the output of spectrum may vary. The phase of the highly reflective side occurs at one point where two longitudinal modes have the same cavity gain. By this reason these AR/HR devices have to be screened at manufacturing and poor sided parts are dumped as scrap waste. The phase of cleaves affects the wavelengths and it control the output wavelength of feedback lasers.
In this equipment, you will find a phase shift centre in the reflection band. The devices operate on a single longitudinal mode with coherence length in excess of tens of kilometers. This device can be limited by the temporal noise, which is induced by the self heterodyne. The fibers of these devices are useful in sensing applications where extreme narrow line width is required. The nanoplus.com provides the standard for DFB laser technology as this company has the technology leaders for ultra precise equipments.