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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.
A distributed feedback (DFB) quantum cascade laser [25] is similar to a Fabry–Pérot laser, except for a distributed Bragg reflector (DBR) built on top of the waveguide to prevent it from emitting at other than the desired wavelength. This forces single mode operation of the laser, even at higher operating currents.
Laser resonators are often described as Fabry–Pérot resonators, although for many types of laser the reflectivity of one mirror is close to 100%, making it more similar to a Gires–Tournois interferometer. Semiconductor diode lasers sometimes use a true Fabry–Pérot geometry, due to the difficulty of coating the end facets of the chip.
Laser types with distinct laser lines are shown above the wavelength bar, while below are shown lasers that can emit in a wavelength range. The height of the lines and bars gives an indication of the maximal power/pulse energy commercially available, while the color codifies the type of laser material (see the figure description for details).
Photomicrographs of a DBR laser. A distributed Bragg reflector laser (DBR) is a type of single frequency laser diode. Other practical types of single frequency laser diodes include DFB lasers and external cavity diode lasers. A fourth type, the cleaved-coupled-cavity laser has not proven to be commercially viable.
Laser treatment for hair regrowth is widely promoted as a treatment for male pattern baldness and as an alternative to medications like minoxidil and finasteride. While some science supports the ...
A basic TDLAS setup consists of a tunable diode laser light source, transmitting (i.e. beam shaping) optics, optically accessible absorbing medium, receiving optics and detector/s. The emission wavelength of the tunable diode laser, viz. VCSEL , DFB , etc., is tuned over the characteristic absorption lines of a species in the gas in the path of ...
Danielle Fishel is sharing an update about her health, saying she has completed “active cancer treatment” following her announcement in August that she was diagnosed with DCIS, which stands ...