Explanation of the cw operation of theEr3+3-μm crystal laser

Abstract

A computer simulation of the Er'+ 3-pm crystal laser considering the full rate-equation scheme up to the F7/2 level has been performed. The influence of the important system parameters on lasing and the interaction of these parameters has been clarified with multiple-parameter variations. Stimulated emission is fed mainly by up-conversion from the lower laser level and in many cases is reduced by the quenching of the lifetime of this level. However, also without up-conversion a set of parameters can be found that allows lasing. Up-conversion from the upper laser level is detrimental to stimulated emission but may be compensated by cross relaxation from the S3/2 level. For a typical experimental situation we started with the parameters of Er'+:LiYF4. In addition, the host materials Y3A150» (YAG), YA103, Y3Sc2A130» (YSGG), and BaY&F8, as well as the possibilities of codoping, are discussed. In view of the consideration of all excited levels up to F7/2, all lifetimes and branching ratios, ground-state depletion, excited-state absorption, three up-conversion processes as well as their inverse processes, stimulated emission, and a realistic resonator design, this is, to our knowledge, the most detailed investigation of the Er'+ 3-pm crystal laser performed so far.PACS number(s): 42.55. Rz, 42.60.Lh, 78.45.+h

The route toward a diode-pumped 1-W erbium 3-/spl mu/m fiber laser

“…8 displays the influence of the three interionic processes on the laser output power for a large range of parameters. The sign of the influence is the same as was found for 3-m crystal lasers [19]. The energy recycling by upconversion or cross relaxation is beneficial for lasing, whereas the depletion of the upper laser level by upconversion is detrimental to lasing.…”

“…They represent the intrinsic lifetimes of the system at low dopant concentration and include radiative as well as multiphonon relaxations. The and levels are thermally coupled and are treated as a combined level in the same way as in [19]. The lifetime of the level is estimated from the corresponding lifetime in LiYF .…”

“…The values of the and lifetimes are assumed. It was found in previous simulations that the values of these lifetimes are not crucial for the calculation [4], [19]. The branching ratios are calculated from Judd-Ofelt data of ZBLAN [12] with the procedure used in [19] under consideration of the fluorescence lifetimes of Fig.…”

Spectroscopic excitation and quenching processes in rare-earth-ion-doped AI203 and their impact on amplifier and laser performance

“…From GSA and ESA spectra in Al 2 O 3 :Er 3+ we show that, similar to the situation in other materials [129,130], this transition does not affect pump absorption at 1480 nm and overlaps with the I 9/2 ), which determines the probability of an energy-transfer process [94] in the absence of phonon assistance, delivers a very small microparameter for this ETU process. Nevertheless, this ETU process strongly depletes the metastable 4 I 13/2 level of Er 3+ , thereby diminishing the optical gain [131], and can also be exploited in upconversionpumping schemes to realize a 3-µm laser on the 4 I 11/2 → 4 I 13/2 transition [80]. Several energy-transfer processes between other rare-earth ions have been found to exhibit weak or no spectral overlap at all, yet demonstrate significant transition rates and strong impact on practical device performance, e.g.…”

“…ETU can also be exploited to deplete the lower laser level [79][80][81][82] or generate upconversion luminescence and lasing [83][84][85][86][87]. Different models of macroscopic or microscopic nature have been developed to understand the underlying physical mechanisms and predict practical device performance.…”