Birkedal, Dan

Bischoff, S.

Gregersen, N.

Madsen, M.

Oestergaard, J.

Romstad, F.

We demonstrate that the photonic bandgap effect can be used to control the modes of large area vertical cavity surface emitting lasers. We obtain more than 20 dB side mode suppression ratios in a 10-micron area device

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Downloaded from orbit.dtu.dk on: Dec 18, 2017Large-area single-mode photonic bandgap vcselsBirkedal, Dan; Gregersen, N.; Bischoff, S.; Madsen, M.; Romstad, F.; Oestergaard, J.Published in:Optical Fiber Communications Conference, 2003Link to article, DOI:10.1109/OFC.2003.1247506Publication date:2003Document VersionPublisher's PDF, also known as Version of recordLink back to DTU OrbitCitation (APA):Birkedal, D., Gregersen, N., Bischoff, S., Madsen, M., Romstad, F., & Oestergaard, J. (2003). Large-area single-mode photonic bandgap vcsels. In Optical Fiber Communications Conference, 2003 (Vol. 1, pp. 83-85). IEEE.DOI: 10.1109/OFC.2003.1247506MONDAY AFTERNOOON I OFC 2003 /VOL. 1 I83 e -. = rate optimized e-beam generated phase shifls that result in excellent single mode yield, and a madi- fied epitaxial Structure that in the array can deliver about 50mW chip power at 300 mA drive current (at 35°C temperature) The MEMS mirror is a double-gimbaled smc- me, micromachined in bulk silicon and activated electro-statically by pads underneath. The mirror itself is etched from the device layer of an SO1 wafer, while the pads underneath are patterned onto a glass wafei and bonded to the SO1 wafer The mirror deflects + 3 degrees in the horizontal direction (in the olane of the laser arravl and + 1 degrce i" the &ical direction at a -&ximum voltage of 190 volts not monitor the f;bcr-coupk& &nver directly but monitors the pointing of the MEMs mirror, thus the module is susceptible to power fluctuations caused by creep and thermal shifts. The packag- ing is therefore done with Au-Sn solder to mini- mize creep. The coupling lens is mounted on a kovar pedestal so as to move thermally with the sired and srokd Juring calibrati& for eaih laser channel so that variation of output power with the temperature of the laser assembly can be mini- mized. Another issue with the internal locker design is that a change in the angle of the beam reflected by the mirror will change the transmis- sion through the etalon. If the position on the quadrant detector that corresponds to maximum fiber coupling changes from one channel to the next, the appropriate etalon signal lock point will also change. This problem is again alleviated dur- ing calibration by allowing the lock point to be stored independently far each channel. 3. Results We have demonstrated a module capable of 20mW output power across the C-band (1529- 1568nm) at a channel spacing of 28GHz. Fig. 3 shows the frequency error and the deviation ofthe output power from the power set point that results when the module was switched randomly among 16 channels 1000 times. Frequency accuracy of+/ - LOGHz and power stability of +/-0.5dBm are routinely achieved. The spectral quality is similar the that of fixed wavelength DFBs, with SMSR>40dB, RIN<-l40dB/Hr, and line- width4OMHr. [ I ]  B. Pereshki et al. "20mW Widely Tunable Laser Module Using DFB Array and MEMs Selection.". to amear in IEEE Photonics Techno/- ogy Letters, S e p k b e r  2002. [2] B. Pcreshki et al. "12 element multi-wave- length DFB arrays for widely tunable laser mod- ules" in Proc. Oot id  Fiber Communications ConJ, 2002 T h G G h  MF68 5:30 PM Large-Area Single-Mode Photonic Bandgap VCSELs Techno/&& A/$Lyngdy. Denmayk: E&/P Birkedol@com.dtu.dk. We demonstrate that the photonic bandgap effect can be used to control the modes of large area vel- tical cavity surface emitting lasers. We obtain more than 20 dB side mode suppression ratios in a IO-micron area device. Introdurtlion Compact, efficient, and manufacturable lasers operating in the milliwan-level output regime are increasingly in demand. Applications include, long-wavelength telecommmnications, laser line- of-sight optical communications, optical storage, and high-speed laser printing. The application requires a Gaussian-tpe circular intensity profile that allows beam propagation over large dis- - is that the present designs have used a strong index-guide to confine the mode with a very small mode area as a result. We show that VCSEL devices with large mode areas c m  be obtained using the photonic bandgap  -~ - rr t -.. ~ effec& bfthermal lensing and spatial hole-buming on the performance of large area photonic hand- - Bi. =- gap VCSELs. We report an results ofsuch model- ing and first results from implementing these designs in expenmental devices. Photonic bandean VCSEL desien effective index to create a s i d e  or anti guide far To accurately d & b  the photoniz bandgap shuc- la; to what is u&d in micro Structured optical fibers [7,8]. The latter technique is potentially very attractive, however, the resulu have so far shown low output power. The main reason for this This method ha; been widely used in anal$& df VCSEL performance. We include the effects of spatial hole burning and diffusion of carriers. In the first step we define the lateral and longitudinal 1 ow 8W I -Jo -20 -10 0 10 20 30 Radius [vml Figure 2: Real part ofelectrical field ofthe single made confined to the defect area. Also shown is the lac- em1 variation in the cavity resonance. Authorized licensed use limited to: Danmarks Tekniske Informationscenter. Downloaded on March 10,2010 at 04:08:40 EST from IEEE Xplore.  Restrictions apply. 84 /VOL. 1 I OFC 2003 I MONDAY AFTERNOOON 7 -  6 -  6 -  4 -  z .  5 3 -  2 -  1 -  0 -  T 7  device structure. Then the spatially resolved CUI- rent and temperaNre profiles are calculated for a given bias voltage. Using the local temperaNreS we adjust the refractive index and the lateral structure is sectioned into small domains of con- s m t  longihldinal index vrofile. The cavity reso- . , , , , , , , , , , , , , , , , nance irihcn calculated'for each of ther<lateral domains and h e  global lateral elecoomagneuc mode ran be calcdaied To do this we iterstiv~lv 25 - L 10 E eI 3 ogain. which is a function'of th; local current den- Fundamen-1 PEG mods PBG mode :;L,, .5 0 5 10 15 20 25 30 35 i i ty and optical field rucnyh. and the local upti- cal field strength, u,htch IS a functton of the local optical gain When the iterdtion IS covwrged me can calculate thc mode rcsolxd o~t ics l  nower and side mode  suppression ratios (SMSRj. We can furthermore analyze the near field distribution of the resulting optical modes for different current injection levels. The photonic bandgap effect is achieved by etch- ing the top mirror of the VCSEL. Etching through the top mirror cau~es  a change in the cavity reso- nance: It is the lateral maddation of the.cavity resonance rather than the local effective index that enable the ahotonie bandma effect. We show in iect of etch ra; an the cavity reronanc;, The koduladon of the cavity resonance as a function of the etch depth reflects the periodicity ofthe Bragg mirror. Results To achieve true photonic bandgap confmement of the lasing mode we d e s i a  a structure where a Iat- cral modc IS confined c i a  defect region and pro- hibited irom propagating m il photonic bandgap re~ion due IO multinlc renecuonc We show m Fi-&re 2 the lateral 'eavity resonance modulation in a structure with a defect of IO-micron diameter. The , m c t m  confiner a singlc transrerral mode to The defect as rho*" tn Figlrc 2 In an axidc confined VCSEL uith a IOmicron avcmrc there would nmically be 30 - 40 confmed in the cold .. . cavity. As the injection current is increased heating causes a thermal lens to form in the defect region. This thermal lens is resvonsible for a second mode to be confined by'the photonic bandgap regions. This causes the laser to operate on sev- eral transversal modes. To illustrate this we calcu- late the light-current characteristics far the device as shown in Firmre 3. The Firmre shows the total in the SMSR,'which we show in Firmre 4. We ~ e e  that the lascr has a SMSR of moreihan 20 dB in the ~ n j c c t m  uunenr range rim 5 mA - 12 mA We note that thc ~rejent w w N r c  has not WI been optimized with rre,pect to single-Aode'autput- power. We expect to achieve considerably higher single-mode output-power levels in an optimized sttucture. One of the advantages of this structure is that the mode profile is relatively insensitive to the CUI- rent injection level. To illustrate this feature we plot in Figure 5 the radial intensity profile for three different injection levels: near threshold, intermediate, and just before onset of multi-mode operation. h the present case the halfwidth ofthe intensity profile changes less than a few %, which is considerably bener, than for oxide confined VCSELs. The stability of the mode profile to CUI- rent and hence temperature is important for el%- cient coupling to single mode fibers. Conclusions We have demonseated that large-area single- mode VCSELs can made using the photonic handsan effect. There lasers have ootential to which enable a range of iew application for VCSELs. We have furthermore demonstrated the stability of the single hnnwersal mode for increasing injection current. We are currently implementing the present design and well show Erst experimental results. References 1. For a recent review see: J.-F.P. Seurin, S.L. Chuang, L.M.F. Chirowky, and K.D. Choquene, "Novel VCSEL designs deliver high singlemode output power", Laser Focus World, pp. 119-122, Figure 5:  Near field profiles of the lasing mode. The figure shows profiles of the optical intensity at the laser facet for three different current injection levels. Authorized licensed use limited to: Danmarks Tekniske Informationscenter. Downloaded on March 10,2010 at 04:08:40 EST from IEEE Xplore.  Restrictions apply. May, 2002. 2. B. I. Koch, J. R. Leger, A. Gopinath, Z. Wang, and R. A. Morgan, "Single-mode vertical cavity surface emittine laser bv eraded-index lens svatial filtering," Appi Phys.'&tt., vol. 70, pp. i359- 7?61 1997 _-_.. 3 Y A Wu. C. J Chang-Harnam, and R. Nabiev, "Single mode c m m m  from a parrive-antiguide- rciion i c n i c a 1 . c ~ ~ ~  surfareenininn laser,'* E h "  Len., VOI. 2$, pp. 1861-1863, i993. 4. T.-H. Oh, M. R. McDaniel, D. L. Huffaker, and D. G Deppe,, ':Cavity-induced antiguiding in B selectivelv oxidized vertical-caviw surface-emit- ting laser? IEEE Photon Techno< Lett., vol. IO, pp. 12-14, Jan. 1998. .~ 5 H. Manimson. J .  A \ 'uhric ' .  and A Larsron, "Single-Mode Power Dependence on Surface Relief Sue f x  \lode-Siabilmd Oxlde-Confined Vertical-Cavity Surface-Emi& Lasen j~ lEEE Photon. Technol. Len., vol. 12, pp. 1129-1131, 2000. 6. H.J. Unold, M. Golling, F. Mederer, R. Michalzik, D. Supper, and K.J. Ebeling, "Sin- glemode output power enhancement of InGaAs VCSELs by reduced spatial hole burning via sur- face etching," Elecmn. Lett., vol. 37, pp. 570- 571,2001. 7. ECOC: H.J. Unold, M. Golling, R. Michalzik, D. Supper,, a,nd K.J. Ebeling, "Photonic crystal surface-emmmg lasers: tadonng waveguiding for single-mode emission," ECOC 2001 Amsterdam, The Netherlands. 8. D.-S. Song, S.-H.Kim,H.-G.Park,C.-K.Kim, and Y.-H. Lee, "Single-fundamental-mode photo- nic-crystal vertical-cavity surface-emitting lasen," Appl. Phys. Lett., vol. 80,pp. 3901-3903, 2002. 9 . G R  H a d 3  "Effective . , , index model for veni- cal-cavity s ace emitting lasen," Opt. Len.. vol. 20, pp. 1483-1485, 1995. 10 J-A. Vukujic. l i  Maninson. J.S. Gurtavsran. and A. Larrion, "Sumeriral Optimization of the Sin& Fundamental Mode Ouraut from a Surface Mozified Vertical-Cavity ' Surface-Emitting Laser," IEEE I. Quant. Elec., vol. 37, pp, 108- 117,2001. MF69 ~ : B ~ P M  High Power C-Band Semiconductor Booster Optical Ampllfier M. Dagenais, P. Heim, S .  Saini, S .  Wilson, R. Leavitt, A. Yu, T. Horton, V. Lueiani, D. Stone, Y. Hu, Quanhrm Photonics Inc. Jessup, MD, Email: dogenais@puonhrmphoronier.com. A semiconductor boaster optical amplifier chip with a saturation power of 20.2 dBmhas been demonstrated to operate over the whole C-band. This booster amplifier was used in 10 Gb/s propa- gation experiment over 80 h of single mode fiber Introduction As the complexity and functionality of WDM sys- tems increases, the need for optical amplification also increases. Until now this need has been ful- filled, to a large extent, by erbium doped fiber amplifiers (EDFAs). So far, optical amplification has been used in boaster and in-line applications, as loss compensators for chromatic and dispersion compensators and also as pre-amplifien for high sensitivity detection. Upcoming applications include reconfigurable add-drop multiplexers and dynamic gain equalization. Recently, we have seen tremendous pressure toward reducing the cost of optical components. Lower cost optical amplifiers have appeared on the market. These include erbium doped waveguide amplifien (EDWAs) and semiconductor optical amplifiers (SOAs). SOAs have found uses in booster appli- cations for boosting the power of fixed frequency and hmable semiconductor lasers (i.e. hmable VCSELs) and as in-line amplifien. For these applicaimr. high ,awaimn~ power dber h e  n hole C-band and low noire-figwe 10 P I C S C ~ C  cimal ouslm u i  thr incident beam are reouircd MONDAY AFTERNOOON / OFC 2003 / VOL. 1 / 85 E -. - I" I I I I I 70 I 1 f 5 m y 1  L 40 0 100 200 300 430 500 1 e C .- d I @ 500 mA a @  1540 nm TEC : 25OC 16 I . -  8 12 16 20 24 Output Power (dBm) F@c 3. G i n  rablratian wriw output optical power 1500 1520 1540 1580 1500 wawlw&lth ("F-I 4. Dependence cfPssS on urivclcqth at diEmnt cum& R&ent$, hiih saturation power SOAs ha& been discussed [1,2]. Here, we report an an ultra-high Authorized licensed use limited to: Danmarks Tekniske Informationscenter. Downloaded on March 10,2010 at 04:08:40 EST from IEEE Xplore.  Restrictions apply. 

Large-area single-mode photonic bandgap vcsels

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Large-area single-mode photonic bandgap VCSELs

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Large-area single-mode photonic bandgap vcsels

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