how does a fiber laser work?–Lisa from Ruijie fiber laser cutting factory
The fiber used as the central medium for your laser will have been doped in rare-earth elements, and you will most often find that this is Erbium. The reason this is done is because the atom levels of these earth elements have extremely useful energy levels, which allows for a cheaper diode laser pump source to be used, but that will still provide a high output of energy.
For example, by doping fiber in Erbium, an energy level that can absorb photons with a wavelength of 980nm is decayed to a meta-stable equivalent of 1550nm. What this means is that you can use a laser pump source at 980nm, but still achieve a high quality, high energy and high power laser beam of 1550nm.
The Erbium atoms act as the laser medium in the doped fiber, and the photons that are emitted remain within the fiber core. To create the cavity in which the photons remain entrapped, something known as a Fiber Bragg Grating is added.
A Bragg Grating is simply a section of glass which has stripes in it – which is where the refractive index has been altered. Any time that light passes across a boundary between one refractive index and the next, a small bit of light is refracted back. Essentially, the Bragg Grating makes the fiber laser act like a mirror.
The pump laser is focused into cladding that sits around the fiber core, as the fiber core itself is too small to have a low-quality diode laser focused into it. By pumping the laser into the cladding around the core, the laser is bounced around inside, and every time that it passes the core, more and more of the pump light is absorbed by the core.
Post time: Jan-18-2019