Allerman, Andrew A.

Choquette, Kent D.

Fischer, Arthur J.

Geib, Kent M.

Hadley, G. Ronald

Hindi, Jana Jo

UNT Digital Library

.,*f s+v&z63i-2Q - 20(542c“*.High-Power Single Mode Operation of HybridIon-Implanted/Selectively-Oxidized VCSELSG. Ronald Hadley, Kent D. Choquette, A. J. Fischer, K. M. Geib, A. A. Alle&an, andJ. J. HindiCenter for Compound Semiconductor Science & TechnologySandia National Laboratories‘~ ~.~-~ J $/ ~~P.O. BOX 5800Albuquerque, NM 87185(505)844-4015 SEP f 52000(505)844-8985 (FAX)grhadle@sandia.gov OsTjAbstractWe report the design and testing of a novel 850nrn hybrid vertical cavity laseremploying ion implantation and selective oxidation to independently define the gainregion and mode size for optimal high-power single-mode operation.DISCLAIMERThis repofi was prepared as an account of work sponsoredby an agency of the United States Government. Neitherthe United States Government nor any agency thereof, norany of their employees, make any warranty, express orimpiied, or assumes any legal Iiabiiity or responsibility forthe accuracy, completeness, or usefulness of anyinformation, apparatus, product, or process disciosed, orrepresents that its use wouid not infringe privateiy ownedrights. Reference herein to any specific commercialproduct, process, or service by trade name, trademark,manufacturer, or otherwise does not necessarily constituteor impiy its endorsement, recommendation, or favoring bythe United States Government or any agency thereof. Theviews and opinions of authors expressed herein do notnecessarily state or refiect those of the United StatesGovernment or any agency thereof.DISCLAIMERPortions of this document may be illegiblein electronic image products. Images areproduced from the best available originaldocument.. .* fHigh-Power Single Mode Operation of HybridIon-Implanted/Selectively-Oxidized VCSELS .G. Ronald Hadley, Kent D. Choquette, A. J. Fischer, K. M. Geib, A. A. Allerman, andJ. J. HindiCenter for Compound Semiconductor Science & TechnologySandia National LaboratoriesP.O. BOX 5800Albuquerque, NM 87185(505)844-4015 (505)844-8985 (FAX)Selectively-oxidized vertical-cavity surface-emitting lasers have demonstrated recordperformance. However, due to the strong index confinement created by the low-indexoxide layers, devices with large enough diameter to produce significant power virtuallyalways operate in multipIe transverse modes[ 1]. High-power single-mode operation isdesirable in many applications such as optical storage and printing due to the ability totightly focus the laser output. One method of providing the mode selectivity necessary toinsure single mode operation in a large diameter VCSEL is to independently control thesize of the gain region and that of the optical mode[2]. We first present numericalsimulations that quanti~ this approach by predicting lateral mode discrimination fordifferent sized gain apertures. These calculations are experimentally confirmed by thefabrication and testing of 850 nm VCSELS employing hybrid ion implantatiordselectiveoxidation that produce a single-mode output of more than 5 mW.We performed VCSEL simulations using a 2D axisymmetric finite-difference codethat solves for cavity eigenmodes including both mode shape and energy loss rate for arealistic VCSEL structure that includes gain and loss in the quantum well(s). We chose aVCSEL comprised of a 1-Z cavity containing a single 100A quantum well with 34 DBRpairs below and 21 above the cavity. Optical mode confinement resulted born twoquarter-wave oxide layers positioned just above and below the cavity with fixed 10pmdiameter. Gain in the quantum well was made uniform within some aperture radius andgiven a large negative value outside the aperture to simulate the unpumped quantum well.For each aperture diameter, the gain was set so that the fundamental mode was atthreshold, and the modal loss of the most competitive higher-order modes computed. InFig. 1, the loss has been normalized by the cold-cavity loss of the iindamental mode.Symbols plotted along the vertical axis correspond to the first-order radial mode havingm=O. These results show clearly that with a 10 pm gain aperture there is virually no modediscrimination, but that as the diameter is reduced below the oxide diameter significantmode discrimination appears. Gain aperture reduction is of course limited by the resultingseveralfold threshold increase predicted by the model (and observed experimentally).This concept was realized in the laboratory by using conventional proton impkmtationto define a gain region independently from the size of the oxide aperture, as shown in Fig.2. Devices with equal gain and oxide apertures lased multimode as expected. However,when the gain aperture was decreased to about half the oxide aperture, single mode. toperation ensued up to the device’s peak output, in agreement with the simulations. Forexample, VCSELS with 6 pm implant diameter md 12 pm oxide diameter display theoutput characteristics shown in Fig. 3. Thk device Iased single mode with 30 db of sidemode suppression up to its maximum output power of 5.2 mW. Higher single-modeoutput power is expected from similar devices designed with more aggressive outputcoupling. Sandia is a multiprograrn lab operated by Sandia Corporation for the U.S. Dept.of Energy under Contract DE-AC04-94AL85000.References[1] K. D. Choquette and K. M. Geib, “Fabrication and Performance of Vertical CavitySurface Emitting Lasers”, Chap. 5 in Vertical Cavity Surface Emitting Lasers, ed. C.Wilmsen, H. Temkin and L. Coldren, Cambridge University Press (Cambridge, UK)1999.[2,] K. D. Choquette, A. A. Allerrnan, K. M. Geib and J. J. Hindi, “Lithographically-Defined Gain Apertures Within Selectively Oxidized VCSELS”, CLE02000, paperCtuL6, San Francisco, CA (May 2000).Pmdktad Mode Discrimination87648111n ___-----–+-; OW.~—. -.–. –._. _._. _._._.\.,-1 E I IoAzimuthal’Mode No.2Fi~ 1 p~ediCt~d m~d~] 10SS for different high. ~rder~~de~ ~dgain aperturesk’”!Fig. 2 Hybrid VCSEL schemaric6-5 F=A.=: ‘ELI-4 ;3 ~ Fig. 3 Measured LI curve for 6 pm gain apertureg3 and 12 ~m oxide aperture. Inset shows side-mode-2 84? 847 85?‘xl.-~ Wa\elen@ (1A)suppressionat current indicated by arrow,2EMC52461 6 pm&a implant12 x 12 Mm oxideo0 ~ ‘4 6 8 10 12Current (MA)

High-Power Single Mode Operation of Hybrid Ion-Implanted/Selectively-Oxidized VCSELs

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High-Power Single Mode Operation of Hybrid Ion-Implanted/Selectively-Oxidized VCSELs

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