Dfb laser is with higher production cost and suitble for long distance transmission.
Fp laser vs dfb laser.
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Distributed feedback dfb laser diodes are lasers that have a grating structure in the cavity that produces multiple reflections throughout the cavity.
Fabry perot laser diodes are lasers whose mirrors are simply the flat cleaved surfaces at the ends of the laser chip.
For example the tramission distance is generally within 20 km the speed is generally within 1 25 g and the fp is divided into two wavelengths 1310 nm 1550 nm.
In summary fp and dfb lasers working principles are different.
Comparison of fp vcsel and dfb laser diode in optical transmission for mr rf coil array c.
This leads to narrower linewidths than are produced by fp lasers.
While the spectral width of the fp laser is relatively wide it is a multi longitudinal mode laser.
Chart from reference 3.
With increasing current the wavelength of the laser red shifts as the device heats up.
The spectral width of the dfb laser is generally narrow is a single longitudinal mode with distributed negative feedback.
Eventually a red shift occurs to a higher gain mode leaving a gap in the tuning range.
The main difference can be got by the form between the fp and dfb laser is that the spectral width is different.
Following are the characteristics of this dfb laser type.
Shen 1electrical and electronic engineering the university of hong kong hong kong china people s republic of introduction.
A distributed feedback laser dfb is a type of laser diode quantum cascade laser or optical fiber laser where the active region of the device contains a periodically structured element or diffraction grating the structure builds a one dimensional interference grating bragg scattering and the grating provides optical feedback for the laser this longitudinal diffraction grating has periodic.
This is a fatal mode hop if the desired wavelength exists within the gap.
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In this tutorial we will quickly explain what is a dfb.
It is more precise compare to fp laser type.
Their operating wavelength threshold current and forward voltage are also different.
Distributed feedback laser selects only one principal wavelength in fp laser spectrum.
The fp laser fp fabry perot laser is a semiconductor light emitting device that emits multi longitudinal mode coherent light with a fp cavity as a resonant cavity.
Typical tuning curve of a dfb laser 3.
It has output power capability much lower than fp laser type.