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 bonded crystal of erbium glass and also white glass is also erbium glass. This paper generally presents Er, Yb doped glass. The glass substrate in question is not usual glass however phosphate glass.
Er3+, Yb3+ co-doped phosphate glass (Er, Yb: phosphate glass) is a preferred and generally used active device for lasers generating in the “eye-safe” scary series of 1,5-1,6 µm.
What is phosphate glass?
Phosphate glass is a glass product that primarily includes phosphorus pentoxide (P2O5) as well as usually additionally includes other chemical components. It can be used as a laser gain medium in bulk as well as fiber. Its primary advantage is its high compatibility with rare-earth ions (see rare-earth-doped gain media), such as Erbium (Er3+), ytterbium (Yb3+), and also neodymium (Nd3+) ions.
To put it simply, the phosphate glass types can be doped with a high focus of laser-active rare planet ions without triggering negative impacts such as clustering, which will certainly generate a quenching result and affect the efficiency of the laser. The doping focus in phosphate erbium-doped fiber is a lot more than that in quartz fiber, and also it can increase by numerous percent factors. The high doping focus of phosphate enables brief fiber lasers as well as amplifiers, which are not the only benefits of the glass however likewise consist of:
- The brief fiber laser resonator can obtain a huge free spectrum variety, making it much easier to achieve single-frequency procedure.
- Dispersed responses lasers are brief, whereas highly doped phosphate fibers permit more reliable pump absorption.
- Ultrashort pulsed fiber lasers are less at risk to nonlinear results if they use shorter fibers.
What’s the mechanism of erbium glass?
Phosphate glass integrates a lengthy life time (~ 8 ms) of 4I13/2 Er3+ top laser degree with a reduced (2-3 ms) lifetime of 4I11/2 Er3+ level that remains to be in resonance with Yb3+ 2F5/2 discharged up state. Quick non-radiative multi-phonon recreation from 4I11/2 to 4I13/2 level considerably reduces the back-energy transfer and up-conversion losses due to the interaction in between Yb3+ and Er3+ ions, delighted at the 2F5/2 together with the 4I11/2 degrees, specifically.
Essentially continuously, erbium-ytterbium-doped phosphate glass is pumped with wavelengths around the 975-nm absorption height of Yb3+ ions. That causes the excitation of the ytterbium ions. Afterward, Yb ions might transfer the excitation power to surrounding erbium ions. After a reliable power transfer, one preliminary has an Er3+ ion in the 4I11/2 state (even more particularly, a Stark degree manifold), which has similar excitation energy as the Yb3+ ions. From that state, the ions generally undergo a quick non-radiative change to the state 4I13/2, regularly used as the top laser degree. Such non-radiative modifications happen based upon multi-phonon discharge, gave that the phonon power of the item is high and sufficient (which holds for silica fibers, as an example).
Application of Er, Yb: glass in Erbium glass laser
- Er, Yb: glass is additionally an exceptional item for upconversion luminescence. Laser got the environmentally friendly as well as red laser from erbium-doped glass fiber, and individuals additionally observed violet upconversion light. The upconversion luminescence of Er: phosphate glass delighted by Nd: YAG was checked out. The upconversion laser will certainly be really functional in great deals of applications.
- Er, glass is a pure three-level laser device. As a result of this, it requires to pump mostly all the energised glass components. The non-pumped locations give laser light absorption losses. In the case of the standard pole plan, the non-pumped rod requires to be as brief as feasible.
- The optical excitation of the Yb, Er glasses (specifically chromium-free ones) happens primarily making use of Yb ions. The only Yb absorption band lies in the near-infrared spectral array (900– 1000 nm). Water discontinuation in this spectral range is 1 cm-1. Because of this, Er glass can drastically lower the water-cooled laser efficiency due to pump light absorption in the water layer surrounding the flashlamp and the laser pole.
