VNU Journal o f Scicucc M athcinutics - Physics 24 (2008) 89-96 Wavelength shift in inicrosphere lasers Tran Thi Tam^ % D ang Quoc Trung-, Trail A uh Vu“, Le H uu Minh^, Do N goc C hung“ I'a m llv o f H ngineenng Physics and Nano-Technolo’ sim ilar to the S chrodinger equation w ith a pockct-like pseudo po ten tial d u e to th e refractiv e in d ex d isco n tin u ity at the surface o f the sphere The m iư o r associated to a m irro r reflectio n s>nimetr>' operation gives an even sym m etric p o tential s>'mnietric ỉ>,g and antisym m etric eig en states asso ciated resp ectiv ely to b lu e-shiftcd (s>Tiimctric) and red-shifted Tran Thi Tam et a l / 1ốì;)9.00 25 00 r liV? 16ŨỒ95 I 20 00 r \ I /■ 16^,90 15.00 f ÌỞ0S.85 i) / 10.00 r 160S.S0 5-CfO r 16ŨS.75 lổOặ.70 OS 95 Journal o f Science, M athematics - Physics 24 (2008) 89-96 00 (d/t:-) a) 2.5 V/ “ 05 15 25 b) Fig D ependence from sphere-tnirror distance of: a) W iivelength b) Intensity a) b) Fig WGM wavelength shift of a) n m ; b) 5 n m (antisym m etric) w av elen g th s T aking into account th e vcctor asp ect o f T E and TM m odes and that the electrical field is qu asi-tan g en tial to the sphere for T E m o d es (q u asi-rad ial fo r T M m odes) fo r a large diam eter {D > A), th u s T E m odes are associated o n ly to sy m m etric states and T M to antisym m etric states T he m odel explained th e resonance shift b u t it does n e t ta k e into acco u n t the m etallic properties o f the m iư o r and could n o t give reasonable ex p lanation on q u e n c h in g o f som e m odes observed The coupling o f the T M m odes (electric field norm al to th e su rface) w ith th e surface w aves o f the m etal plane m ay lead to th e ir quenching T he w id th o f the laser m ode is narrow er th a n ou r e x p e rim e n t’s eq u ip m en t resolution, so we not investigate its behavior Conclusions The m icrosphere W G M lasers w as realized in E i^+ /Y b ^+ co -d o p ed p h o sp h ate glass using n m pum p, to take full advantage o f energy tra n sfe r effect from ion Y tterb iu m to ion Erbium The coupling w as earn ed out b y fiber h a lf tap er te ch n iq u e in tw o sch em es, both gave good results The single laser line p o w e r m ay reach n iy w ith only b m W to tal p u m p pow er, and laser range 96 Tran Thi Tam et al / IW U Journal o f Science, Mathematics - Physics 24 (2008) 89-96 extends from Ì5 2 n rn to 1618.972m T he red shift ciTcct, w hich associated w ith the th cn n al ef fect occuư cd insider sphere took place u n d er strong pum p We have experim entally observed only a em issio n w a v e le n g th s h ift b y ab out n m to the shorter sid e (b lu e { sh ift) w h ile v a n i n s the d istan ce sphcrc-m iư or from lO O ^m ( ~ D) to IQf nn ( ~ O.ID) T he proposed red shift have not been confirm ed A ck n o w led g em en ts T h is w ork is supported b y a N ational B asic R esearch Program K T-04 The authors thank CN R -IFA C , N cllo C arrara Institute o f A pplied Physics, 50127 Firenze, Italy for supplyina the Er^+ /Yh^+ co-doped p h o sphate elass References [1] M Cai, o Painter, K.J, Vahala, RC Scrcel, Fibcr-coupplcd inicrosphcrc laser, OpticsLetlers Vol 25 No 19 (2000) 1430 [2] S Schillcr, R.L Byer, High-rcsolution spectroscopc of whispering gallery modes in large diclcctric spheres, Optics Letters Vol 16 (1991) 1138 [3] R.w Boyd, J.E Heebncr, Sensitive disk resonator photonic biosensor Applied Optics Vol 40, No 31 (2001) 5742 [4] B.E Little, ST Chu, H.A Haus, J Forcsi, J.p Laine, Microring resonator channel dropping filters Journal o f Lightwave Technology Vol 15 (1997) 998 [5] F.c Bloni, D.R Van Dijk, H.J Hockstra, A Driessen, ThJA- Popma, Experimental study of intcgratcd-optics micro cavity resonators: toward an all-optical switching dcvicc, Applied Physics Letters Vol 71 (1997) 747 [6] B.R Johnson, Theory of morphology-dependent rcsonanccs: shape resonances and width fomiulas, y Opt Soc Am A 10 (1993) 343 [7J z.p Cai, A Chardon, H.Y Xu, p Fcron, G.M Stephan, Laser characteristics at 1535 nm and Ihcnnai cỉĩccts 0Í'an ErYb phosphate glass microchip pumped by Ti;sapphire laser Opt Comm 203 (2002) 301 [8] z,p Cai, H.Y Xu, G.M Stephan, p, Fcron, M Mortier, Rcd-shift in Er:ZBLAJ>iP whispering gallery mode laser Opt Comm 229 (2004) 311 [9] P Feron, c Amaud, M Boustimia, G Nunzi-Conti, G Righinib, M Mortierc, optical feedback on V'hispcring gallciy mode laser, Proc o fS P IE Vol 5451 (2004) 199 ... in H F or b y heating and strctch in g a standard telecom m unication sin ale m ode at 1.55 ịirn fib e r u n til b reakinti it, usin s either C(3-2 laser or fusion optical splicing system T h... y ch o o sin s the coupling po in t in the h a lf ta p e r i.e adjusting th e distance from tip to acccptancc po in t w c m ay also find the appropriate p o sition to sclect one lasing m ode... received b y optical m ethod W hen increasing th e pum p intensity w e obtained laser oscillation B ecause o f the d ifficu lty in quantifying pu m p portio n coupled in sphere, w e controlled o nly