Harder, C.

Lüthy, W.

McFarlane, R.A.

Meier, H.P.

Pollnau, Markus

Spring, R.

Weber, H.P.

Wittwer, S.

English

University of Twente Research Information

260 / 'Ihutsday CThll8 An Optimized Diode-Pumped BaY2Fg:Er (7.5 at.%) Laser at 2.8 pm 3+ S. Withver, M. Pollnau, R. Spring, W. Liithy, H. P. Weber, R A. McFarlane ', Ch. W?, H. P. Meie?, Institute of Applied Physics, Univerfity of Bern, Sidlerstrasse 5, CH-3012 Bem, Switzerland, Tel. HI-31-631 8937,Fax+4,J-31-6313765, Hugh~ResearchLaborarories,3011MalibuCanyonRoad, Malibu, CA 90265, USA, I8M Research Division, Z!3rich Research Laboratory, Smerstrasse 4, CH- 8803 Riischliion, Switzerland The potential surgical applications of 2.8-pan radiation due to its strong absorption in water and thus in biological tissue has motivated the investigation of laser operatioa in erbim-doped hast materials. Modem surgical applications demand a compact laser system with high output power. GalnAs diode lasers at 970 nm are an excellent pump source for Er3+ lasers and allow the desired compactness.lbe best pump wavelength for an e r b i  3-pn laser is 970 nm leading to a transition into the upper laser [I]. Fluoride hosts promise high efficiency.'Ihis has been confumed by several srperiments, that have bgn raising the efficiency in LiYFh:E2+ up to 40 % [2] with Ti:sapphbpumphg and 35 % [31 with diodp pumping. The ophization of the slope efficiency for LiYF4:E? lasers is still assumed to pnreed towards the theoretically pralicted efficiency mavimum of 56 % 141. Efficient lasers are also q r t e d  h BaY2F8: Er3+. For this crystal we expect a similar efficiency as in LiYF4: E?, especmy for optimized erbiumconcentratjonsof10to15at.%[5). 0n1y few experiments, however, are reported so EU on her-diode-pumped fiY2F8: EJ+.  he spectral properties of such a diode-laser pumped system have not yet been described and with the goal to nadr a high slope efficiencythe laserparametem bavetobe optimized. In our report we describe the optimiZaton of a BaY&:EP+ laser with respect to a high slopc e f 6 c h ~ .  The measurements are carried out with a nearly h a n a d c  wonator. R " t o r  le&, cavity reflectance and the focus of the pump beam are optimized. Tbe sped" of the unitted wavelengths at 2.7 to 2.8 pm is measured as a funaion of absorbed pump power. The thnshold is as low as 16 mW. The best slope efficiency of = 24 % is reached for a nearly h e m i w d c  resolliuor with rene*ance of Ri&& = 97.6 %and a pump beam focused with a Iws offi=20 m. %s work was supported in part by support by the U. S. Air Force Oflice of Scientific Resear& unde.r CoaeactNo. F49620-94C-0018. Swiss Priority Program Optique. R A. McFarlane admowledges 111 R. C. Stomman, I. G Lynn, L. Esterowitz lEEE J. QuantumElearm. 1 (4), 1041 (1992) R Spria& M. Polloau, S. Wittwer, W. fithy, R P  Weber, in Adv. Sdid-State Lasers Tech. Digest 262-264 (1996) T Jensen, A. Dienin& G H u k ,  CLEO 15, OSA T d C d  Digsr Series (optical Society Of America, Washiagton Dc, 1999, postdeadline paper CPD29. M. Pollnau, R Sp&g, Ch. Ghisler, S Wittwer. W. Lathy, H.P. Weber: to appear in IEEE Joumal of Quantum ElectronicS 32 (4), (19%). M. Pollnau, W. Liithy, H P. Weber, T. Jusen, G. Huber, A. cassanho, H.P. J-RA.McFarlaoe,toap~mOpticsLetters31 (I), (1996). [2] f3] [4] [SI CThll9 EfTect of gamma radiation on performance of Cr, Tm, Ho:YAG a i d  Er:YAG lasers S.Kaczmarek, Z.Mierczyk, K.Kopczynski - Institute of Optoelectronics. h.pLiT, 2 Kaliski Str., 01- 489 Warsaw, Poland A.O.Matkovsky, D.Yu.Sugak, - SRC "Carat", R%D Institute of Materials, 202, Stryjska Str., 29003, Lviv, Ukraine A.N.Durygin - Institute of Physics, Ukrainian Academy of Science, 46 Nauka AV ,252650, Kiev, Ukraine ZFrukacz - Institute of Electronic Materials Technology, 133 Wolczynska Str ,01-919 Warsaw, Poland Summary It is well-established that color centers (CCs) produced by ionizing radiation or short-wave radiation of the pump lamp, strongly influence the optical characteristics of yttrium-aluminium garnet single crystals [I-41. However, the possibility of positive effect of ionizing radiation on optical output of YAG lasers should not be rejected. The present work regards the effects of gamma radiation on performance of Er:YAG and CTH:YAG lasers. M e r  gamma irradiation of  Er:YAG crystals, a wide, complex AA band appears within the range of 200-930 nm. The peaks of absorption are placed in the surroundin s of 240, 3 IO, 400 and 625 nm. With the increase of gamma irradiation dosage level from I O  tolo' Cy, the AA values grow larger and larger and become saturated for dosage levels of IO4- I O6 Cy After gamma irradiation of CTHYAG crystal, AA bands appears within the range of 250-710nm with some discrete absorption peak at 255, 320, 385 and 500 nm. it. Stable at room temperature CCs, could be the results of defects of cation sublattice, oxygen vacancies or defects connected with ions of non-controlled impurities. For the rods of CTH:YAG without pre-annealing, the laser output energy increases immediately afier irradiation. The changes have the stable character - the output laser energy stay the same after even 80 days from irradiation and after many pulses of pump xenon lamp. The increase of the laser output energy is also observed for Er YAG crystal after influence of gamma-quanta. At the pumping level of 205 J, the output energy increases from 75 mJ form noninadiated crystal to 135 mJ for the sample irradiated. The obtained results point to the direct influence of the CC on the processes of formation of the population inversion of the laser levels of Er:YAG and CTH:YAG crystals. B Literature 1. Karaseva, N.J.Konstantinov, V.V.Gromov, (in Russion) "Nature of radiation color centers in single crystals of yttrium aluminium garnet", Radiat.Phys.Chem., vo1.26, No.6, pp.723, 1986 2. P.K.Habibulajev, I.R.Biedilov, H.B.Bejsembajeva, (in Russion) "Radiationally activated process in solid-state lasers", Taszkient, FAN, p.3 16, 1988 3 .  A.O.Matkowski, D.Yu.Sugak, S.B.Ubizski, O.I.Shpotiuk, E.A.Chemyj, N.M.Vakiv, V.A.Mokshycki, (in Russion) "Influence of ionizing radiation on optoelectronic materials", Lvov, Svit, p.212, 1994 4. T.S.Rose, M.S.Hopkins, R.A.Fields, "Characterization and Control of Gamma and Proton Radiation Effects on the Performance of Nd:YAG and Nd:YLF Lasers", IEEE of Quantum Electronics, vo1.31, N0.9, pp 1593-1602, 1995 Authorized licensed use limited to: UNIVERSITEIT TWENTE. Downloaded on May 28,2010 at 08:47:41 UTC from IEEE Xplore.  Restrictions apply. 

An optimized diode-pumped BaY2F8:Er3+(7.5 %) laser at 2.8-µm

https://ris.utwente.nl/ws/files/6137236/CLEO-E_1996_Wittwer.pdf

An optimized diode-pumped BaY<sub>2</sub>F<sub>8</sub>:Er<sup>3+</sup>(7.5 %) laser at 2.8-µm

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