(1) What is an Er, Yb: phosphate glass?
The glass doped with Er and ytterbium ions is Er glass; Glasses doped with erbium, ytterbium, and chromium ions are additionally erbium glasses; the dual bound crystal of erbium glass and also white glass is also erbium glass. The glass substratum concerned is not usual glass but phosphate glass. This paper mostly presents Er, Yb doped glass.
Er3+, Yb3+ co-doped phosphate glass (Er, Yb: phosphate glass) is a preferred and usually used active device for lasers generating in the “eye-safe” scary series of 1,5-1,6 µm.
(2) What is phosphate glass?
Phosphate glass is a glass material that generally includes phosphorus pentoxide (P2O5) and consists of various other chemical elements. It can be made used as a laser gain tool wholesale and fibre. Its primary advantage is its high compatibility with rare-earth ions (see rare-earth-doped gain media), such as Erbium (Er3+), ytterbium (Yb3+), and neodymium (Nd3+) ions.
Simply put, the phosphate glass species can be doped with a high concentration of laser-active rare earth ions without triggering negative results such as clustering, which will create a quenching result as well as impact the performance of the laser. The doping focus in phosphate erbium-doped fibre is much greater than that in quartz fibre, and also it can enhance by several percentage factors. The high doping focus of phosphate makes it possible for short fibre lasers as well as amplifiers, which are not the only benefits of the glass but also consist of:
- The brief fibre laser resonator can get a big complimentary spectrum array, making it less complicated to achieve a single-frequency procedure.
- Dispersed feedback lasers are brief, whereas highly drugged phosphate fibres allow extra effective pump absorption.
- Ultrashort pulsed fibre lasers are much less vulnerable to nonlinear results if they use shorter fibres.
(3) What’s the device of Er glass?
Phosphate glass combines a long lifetime (~ 8 ms) of 4I13/2 Er3+ leading laser level with a low (2-3 ms) lifetime of 4I11/2 Er3+ degree that remains in vibration with Yb3+ 2F5/2 fired up state. Quick non-radiative multi-phonon entertainment from 4I11/2 to 4I13/2 degree significantly lowers the back-energy transfer and up-conversion losses due to the interaction between Yb3+ and Er3+ ions, thrilled at the 2F5/2 together with the 4I11/2 levels, specifically.
Essentially constantly, erbium-ytterbium-doped phosphate glass is pumped with wavelengths around the 975-nm absorption elevation of Yb3+ ions. That brings about the excitation of the ytterbium ions. Later, Yb ions may transfer the excitation power to neighbouring erbium ions. After an efficient power transfer, one preliminary has an Er3+ ion in the 4I11/2 state (even more specifically, a Stark level manifold), which has comparable excitation power as the Yb3+ ions.
The ions typically undergo a quick non-radiative shift from that state to the state 4I13/2, consistently used as the top laser degree. Such non-radiative adjustments happen based upon multi-phonon discharge, given that the item’s phonon power is high and sufficient (which holds for silica fibres, as an example).
(4) Application of Er, Yb: glass in Erbium glass laser
Er glass is additionally an extraordinary item for upconversion luminescence. Laser acquired the eco-friendly and red laser from erbium-doped glass fibre, and individuals also observed violet upconversion light. The upconversion luminescence of Er: phosphate glass thrilled by Nd: YAG was explored. The upconversion laser will be sensible in lots of applications.
Er, glass is a pure three-level laser tool. Because of this, it needs to pump almost all the energetic glass components. The non-pumped areas are a source of laser light absorption losses. In the case of the conventional post plan, the non-pumped rod needs to be as short as practical.
The optical excitation of the Yb, Er glasses (especially chromium-free ones) happens primarily using Yb ions. The only Yb absorption band lies in the near-infrared spooky range (900– 1000 nm). Water termination in this spectral variety is 1 cm-1. For this reason, Er glass can considerably decrease the water-cooled laser efficiency due to pump light absorption in the water layer bordering the flashlamp and the laser pole.
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