(1) What is an Er, Yb: phosphate glass?
The glass doped with Er and ytterbium ions is Er glass; Glasses doped with erbium, ytterbium, as well as chromium ions are likewise erbium glasses; the double adhered crystal of erbium glass and white glass is likewise erbium glass. The glass substrate concerned is not usual glass but phosphate glass. This paper primarily introduces Er, Yb doped glass.
Er3+, Yb3+ co-doped phosphate glass (Er, Yb: glass) is a preferred as well as typically used active device for lasers creating in the “eye-safe” spooky series of 1,5-1,6 µm.
(2) What is phosphate glass?
Phosphate glass is a glass material that primarily includes phosphorus pentoxide (P2O5) and also typically additionally has various other chemical parts. It can be used as a laser gain medium wholesale as well as fibre. Its main 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.
To put it simply, the phosphate glass types can be doped with a high concentration of laser-active unusual earth ions without triggering adverse effects such as clustering, which will certainly create a quenching result as well as affect the performance of the laser.
The doping concentration in phosphate erbium-doped fibre is a lot more than that in quartz fibre, and also it can enhance by a number of percentage factors. The high doping focus of phosphate allows brief fibre lasers as well as amplifiers, which are not the only benefits of the glass however additionally include:
The brief fibre laser resonator can get a huge cost-free spectrum range, making it easier to accomplish the single-frequency procedure.
Distributed responses lasers are brief, whereas very doped phosphate fibres permit more effective pump absorption.
Ultrashort pulsed fibre lasers are much less vulnerable to nonlinear results if they make use of shorter fibres.
(3) What’s the mechanism of erbium 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 to remain in vibration with Yb3+ 2F5/2 terminated upstate. Quick non-radiative multi-phonon entertainment from 4I11/2 to 4I13/2 level significantly reduces the back-energy transfer as well as up-conversion losses due to the communication between Yb3+ and also Er3+ ions, delighted at the 2F5/2 together with the 4I11/2 degrees, specifically.
Basically continually, erbium-ytterbium-doped phosphate glass is pumped with wavelengths around the 975-nm absorption elevation of Yb3+ ions. That results in the excitation of the ytterbium ions. Afterwards, Yb ions might move the excitation power to surround erbium ions.
After an efficient power transfer, one preliminary has an Er3+ ion in the 4I11/2 state (far more particularly, a Stark level manifold), which has comparable excitation energy as the Yb3+ ions. From that state, the ions generally undergo a fast non-radiative change to the state 4I13/2, frequently used as the leading laser degree. Such non-radiative adjustments happen based upon multi-phonon discharge, offered that the phonon power of the item is high as well as adequate (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 got the eco-friendly as well as red laser from erbium-doped glass fibre, and individuals likewise observed violet upconversion light. The upconversion luminescence of Er: phosphate glass delighted by Nd: YAG was discovered. The upconversion laser will certainly be really useful in lots of applications
Er, glass is a pure three-level laser device. As a result of this, it needs to pump nearly all the energised glass components. The non-pumped locations give laser light absorption losses. In the case of the standard post plan, the non-pumped rod needs to be as short as practical
The optical excitation of the Yb, Er glasses (specifically chromium-free ones) takes place primarily utilizing Yb ions. The only Yb absorption band hinges on the near-infrared spectral range (900– 1000 nm). Water discontinuation in this spectral range is 1 cm-1. Therefore, Er glass can substantially lower the water-cooled laser efficiency as a result of pump light absorption in the water layer surrounding the flashlamp and the laser pole.