IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 49, NO. 11, NOVEMBER 2013 939

Optical Injection Locking of Polarization Modesin VCSELs Emitting at 1.3 μm WavelengthElodie Lamothe, Christopher M. Long, Andrei Caliman, Vladimir Iakovlev, Alexandru Mereuta,

Alexei Sirbu, Grigore Suruceanu, and Eli Kapon

Abstract— Injection locking of polarization modes of 1.3 µmwavelength vertical-cavity surface-emitting lasers (VCSELs) fab-ricated via wafer fusion is investigated. Maps of the injectedmodes in the frequency-power plane reveal the detailed responseof the slave VCSEL to the optical injection, in agreement withnumerical simulations of the system.

Index Terms— Semiconductor lasers, injection locked lasers,VCSELs, polarization.

I. INTRODUCTION

VERTICAL-CAVITY surface-emitting lasers (VCSELs)offer many advantages over their edge emitting coun-

terparts [1], but typically their circularly symmetric cavitysupports two orthogonally polarized, nearly degenerate spatialmodes. One effective method for selecting the polarizationstates of a laser is optical injection locking, implemented byinjecting resonant light from an external master laser (ML) [2].The injection locking process is quite rich, exhibiting both astable locking regime and various dynamical regimes, depend-ing upon the frequency and intensity of the ML beam [3].Operation in the stable injection regime has been shown toimprove the microwave performance of a directly modulatedlaser [4], [5], and is useful for optical signal processing [6].Careful mapping of the response of the slave laser (SL) tothe ML injection is, however, mandatory for exploiting thistechnique of mode selection.

Previous studies of polarization mode injection lockingin VCSELs began with 850-nm VCSELs [7]–[9]. Injectionlocking was first considered in the region of the hysteresisloops [7]. Then, the cw responses and the dynamic responseswere studied in function of ML frequency detuning and power[8], [9]. More recent work has investigated the static [10]and dynamic [11] properties of long wavelength (1550-nm)VCSELs. The injection response is determined by the laserdevice properties such as photon lifetime, carrier lifetime

Manuscript received June 3, 2013; revised July 23, 2013; accepted August 1,2013. Date of publication September 18, 2013; date of current versionOctober 2, 2013. This work was supported by the Swiss National ScienceFoundation.

E. Lamothe, C. M. Long, V. Iakovlev, and E. Kapon are with theLaboratory of Physics of Nanostructures, Ecole Polytechnique Federal deLausanne, Lausanne CH-1015, Switzerland (e-mail: elodie.lamothe@epfl.ch;christopher.long@epfl.ch; vladimir.iakovlev@epfl.ch; eli.kapon@epfl.ch).

A. Caliman, A. Mereuta, A. Sirbu, and G. Suruceanu arewith BeamExpress SA, Lausanne CH-1015, Switzerland (e-mail:andrei.caliman@epfl.ch; alexandru.mereuta@epfl.ch; alexei.sirbu@epfl.ch;grigore.suruceanu@beamexpress.com).

Color versions of one or more of the figures in this paper are availableonline at http://ieeexplore.ieee.org.

Digital Object Identifier 10.1109/JQE.2013.2278554

and gain so using different materials and fabrication methodscan strongly impact the laser properties. For example, thespin flip relaxation rates of electrons in GaAs/AlGaAs andInGaAs/InP quantum wells can differ by a factor of 6 [12],modeling shows this can affect the location of boundaries thatseparate various dynamic behaviors of the laser [8]. Here,we report polarization mode injection locking in wafer-fused1.3-μm VCSELs, including measured and simulated injectionmaps, giving insight into useful regimes for polarization modecontrol.

II. WAFER FUSED 1.3 μm VCSELS

The VCSELs employed were fabricated using wafer fusiontechnology, where the InP-based active cavity is separatelygrown from the passive GaAs-based distributed Bragg reflec-tors (DBRs) and later joined under high temperature andpressure [13]. The active region consists of six compressivelystrained InAlGaAs quantum wells, and a patterned tunneljunction layer provides current and optical confinement. Theparticular VCSEL used emits in a mode linearly polarizedalong the [110]-crystal axis (x-direction) near its thresholdcurrent of 2.7 mA. Polarization switching to the [1-10]-oriented mode occurs at 7–9 mA (y-direction, Fig. 1(a)).

III. EXPERIMENTAL RESULTS

A schematic of the injection locking setup is shown inFig. 2. Light from a pigtailed ML VCSEL is incident upon thetop DBR of the temperature controlled SL VCSEL workingat 10 °C. The lasers are first brought into near-resonance viatemperature tuning, and then the master laser is finely tuned bycurrent variation. At each bias point, the ML and SL spectraare measured using two optical spectrum analyzers (OSAs)of 0.1 nm resolution bandwidth. The process is repeated fordifferent levels of optical attenuation in order to map the SLresponse versus ML power and frequency detuning. Measure-ments are taken for both x- and y-polarization states of theVCSEL modes (parallel and orthogonal optical injection).

Figure 1(b) and (c) show the spectra of the SL biased atI = 2.9 mA (1.04 × Ith), revealing two peaks correspondingto the polarization states of the fundamental transverse mode.Under the free running condition (black trace), the x-polarizedmode oscillates at 1317.6 nm with an output power 20 dBgreater than the y-polarized mode at 1318 nm (77 GHzseparation). Notice that the frequency splitting of 77 GHzin this laser is significantly larger than in shorter wavelength

0018-9197 © 2013 IEEE

940 IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 49, NO. 11, NOVEMBER 2013

Fig. 1. Injection locking below the polarization switching point. (a) Polarization-resolved LI curves. Optical spectra of a VCSEL undergoing injection of(b) x- and (c) y-polarized light.

pol

OSA 1

OSA 2

splitter

90%

10%PCAtteIsoML

SL

BS

MM

M CCDFlip M

O

L

L

Fig. 2. Optical injection locking setup: ML Master Laser, iso optical isolator,atte optical attenuator, PC polarization controller, splitter 10/90 fiber splitter,pol polarizer, BS beam splitter, M mirror, Flip M flip mirror, O microscopeobjective, L coupling lens, SL slave laser, OSA optical spectrum analyzer,CCD charge-coupled device. The optical fibers are in black and the opticalbeams in red.

lasers simply because the structure of the active region and thecarrier confinement mechanisms are different. In our devices,we use a buried tunnel junction that is regrown, and this yieldsrather large birefringence due to growth rate anisotropies in theactive region [14]. We first consider two specific conditionsthat produce the strongest polarization control. Under paralleloptical injection with Pinj = −21.5 dBm incident on the topDBR and a ML frequency detuning of �v = −1.5 GHz (redtrace, Fig. 1(b)), the x-mode shows a maximum enhancementof 5 dB, and the power in the y-mode is reduced by 6 dB.Both modes show a slight wavelength red-shift due to thephase-amplitude coupling within the diode laser [3]. Underorthogonal optical injection (Pinj = −19 dBm and �v =−77 GHz) (red trace, Fig. 1(c)), the power in y-polarizationmode is enhanced by 25 dB, and the x-mode is diminishedby the same amount; thus the injection induces a polarizationswitching in the VCSEL. Because the x-mode is stronglyattenuated under perpendicular injection, this is an indicationthat injection locking occurs, though in general polarizationswitching can occur without injection locking [11].

In Fig. 3, the power maps of the polarization modes arepresented for x- and y-polarization states of the injectedlight. Each data point presents the SL power changes com-pared to the free-running value (color scale). The SL power

changes were measured at the wavelength of the x- or y-mode. When biased near threshold, the power map for x-polarized light (Fig. 3(a)) shows nearly symmetric responsecentered at zero frequency detuning and having a maximumenhancement power of 5 dB. Simultaneously, the power inthe y-mode is depressed, see Fig. 3(b). For increased SLbias (Fig. 3(c) and (d)), the region of stable injection lockingshrinks. The optical power in the x-mode now increases byonly 0.4 dB when injection locked, and there is a region atnegative detuning where the optical power level decreasesdue to competition between the free running and injectedmodes. Comparing this to Fig. 3(d), we see that the powerin the y-mode is enhanced here by several decibels in thissame region. Figure 3(e)–(h) shows the power maps undery-polarized injection around the frequency detuning of the y-polarization mode (–77 GHz). The polarization switch occursin a non-symmetric locking region, exhibiting a stronger effectfor negative detuning. The power in the x-mode is attenuatedby over 20 dB (Fig. 3(e) and (g)), whereas the y-mode isstrongly amplified (Fig. 3(f) and (h)) over the same region.In panels (f) and (h), we show the measured maps whenthe VCSEL undergoes a polarization switching induced byinjection locking. We have plotted the global maximum ofthe relative SL power of the injected spectrum because it isnot possible to represent the power in the y-mode exclusivelywithout introducing artifacts from the reflected master lasersignal. Thus, the region inside the black contour line (red zone)corresponds to the modal power of the y-mode (polarizationswitching region), and the outside region corresponds to themodal power of the x-mode (free-running mode).

IV. THEORY AND SIMULATIONS

A. Rate Equation Model

A common approach for describing optical injection is therate equation model of the optical field and carrier number [5].Polarization switching is a result of cross-gain saturation of theVCSEL modes that exceeds the self-gain saturation [15]. Thisphenomenological model can be derived from a more fun-damental description of the carrier relaxation dynamics [16]under the conditions of large birefringence and fast carrierspin relaxation. Here, we consider optical injection when theslave laser is under constant bias, and this simplified model

LAMOTHE et al.: OPTICAL INJECTION LOCKING OF POLARIZATION MODES 941

Fig. 3. Injection maps (injected power Pinj versus ML detuning �v) forthe VCSEL at two different bias currents, undergoing injection of x-polarizedlight (a–d) and y-polarized light (e–g). Maps display the power changes in thex- and y-polarization modes. Zero detuning refers to the frequency resonanceof the free running x-polarization mode. Stable locking (S) and non-locking(N) regions are indicated on the maps.

captures the essential injection response. We treat the real andimaginary parts of the optical field in terms of photon numberS and optical phase φ. Here, the total number of photonsS corresponds to the photon number in the x-polarizationstate Sx and y-polarization state Sy ; i.e., S = Sx + Sy . Bothpolarization modes are coupled to a single carrier populationN [15], [17]. The rate equations for the x-polarization read:

d Sx

dt=

(�vg

gn (N − Ntr )

1 + εx x Sx + εxy Sy− 1

τpx

)Sx

+β B

VaN2 + 2κx

√Sinj Sx cos(φx − φin j ), (1)

dφx

dt= α

2

(�vg

gn (N − Ntr )

1 + εx x Sx + εxy Sy− 1

τpx

)

−2π�v − κx

√Sinj

Sxsin(φx − φin j ), (2)

d N

dt= Ibias

q− N

τN− �vg

gn (N − Ntr )

1 + εx x Sx + εxy SySx

−�vggn (N − Ntr )

1 + εyy Sy + εyx SxSy . (3)

Equation (1) describes the rate of change of the photonnumber, Eq. (2) the phase evolution and, Eq. (3) the rateof change for the carrier number N . Similar equations holdfor the y-polarization mode, with an extra term in the phaseresponse to account for the frequency separation of bothmodes. A coupling rate term κ0, defined as

κ0 = (vg/2Le f f

)(1 − R)1/2 ,

is introduced to describe the duration it takes for the incidentML light to distribute itself along the effective length of the SLcavity Le f f . Simulation parameters for the slave laser weredetermined through static and dynamic characterization [18] ofthe VCSELs under study. The photon lifetime of the x-modeis calculated from the slope of the LI-curve near thresholdand the theoretical mirror loss. The photon lifetime for theorthogonal polarization mode is chosen to match the measuredoptical spectrum [5]. The S21 modulation response versus biaswas used to find the differential gain and verify the photonlifetime. A series of simulated LI-curves was then used tooptimize the gain saturation terms and produce a polarizationswitch at the appropriate current value. All parameters in(1)–(2) are presented in Table I.

B. Description of Simulation

Numerical simulations were performed by solving the rateequations with the Runge Kutta method. We first establishedthe free-running laser conditions for 10 ns, and then introducedthe injection term and continue the simulation for 20 ns. Werepeat this routine for a range of detuning frequencies andpower levels of the master laser. Regions of phase lockingare found where the phase change with time has decreased tozero. Parameter values used in the simulation are provided inTable I.

C. Comparison With Experiment

The map in Fig. 4(a) presents the measured power in thex-mode when the SL is biased at 3 mA, as well as thecorresponding simulation result. The color scale is set sothat regions showing enhanced signal appear in color andregions showing diminished signal appear on a gray scale.The experimental data are normalized to the free runningpeak power, and plotted as individual squares. Simulated dataare normalized in power to the measured data. By using acoupling factor of κx = 0.325 × κ0, the simulation accuratelypredicts the settings that produce greater cw optical power.This decreased coupling factor can be attributed to an over-estimation of the amount of light that is incident on the SLfacet and non-ideal mode overlap between the injected lightand resonant modes. The experimental data show that the

942 IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 49, NO. 11, NOVEMBER 2013

TABLE I

SIMULATION PARAMETERS

Fig. 4. The injection maps for x-polarized mode under (a) parallel and(b) orthogonal injection. Discrete square points: experimental data, back-ground color: numerical simulation data.

maximum power enhancement is near –1.5 GHz detuning,and analytical solutions of the single-mode rate equations [19]show this type of shift is consistent with nonzero linewidth

enhancement. We find good agreement in simulation by settingα to 0.5, and this was further verified by alignment of theanalytic locking boundaries to our data. The value of αis rather low, but is consistent with that recently reportedin [20], where the authors found α = 0.7 ± 0.4 in theirlong-wavelength VCSEL. When injection takes place outsidethe stability boundary, the optical power oscillates at thedifference frequency of the ML and SL. The amplitude ofoscillation increases as we approach the boundary from theoutside, inhibiting the lasing process and unclamping thecarrier number. Under this condition, the orthogonal modepower increases, but remains unlocked from the ML. Injectionmaps for orthogonal injection are presented in Fig. 4(b), withthe numerical data normalized to the experimental data. Forcoupling parameter κy = 0.2 × κ0 and α = 1.0, simulationpredicts the locking boundary conditions in good agreementwith the experimental data. The new simulation parametersproduce a narrower region of stable injection locking, andshift it by –3.5 GHz. We see that orthogonal injection leadsto strong suppression of the x-polarized mode. Across themajority of the simulation domain, the numerical data predictsthat the power in the y-polarized mode will be increased.

V. DISCUSSION AND SUMMARY

The numerical simulation is in good agreement with theinjection locking experiment results, but predicts a strongerresponse of the VCSEL when injection locked than what wasmeasured. This is likely due to noise in the real system.The lasers may instantaneously unlock due to relative phasefluctuation from spontaneous emission [19]. This could limitthe minimum power for injection locking and the powerenhancement in a locked mode. In the numerical simulation,the linewidth enhancement factor α is used as a free parameterto fit the simulated enhancement region to the measured data.The value reported here is significantly lower than the valuespreviously reported for long wavelength VCSELs [4], [5],so we expect this particular device to show improved per-formance in some applications [4], [6]. It is interesting tonote the difference in α for the two polarization modes. Thisdifference is likely due to the large cavity birefringence andthe frequency-dependence of the material gain. In [11], theauthors report higher α in the lasing polarization mode thanin the non-lasing mode, and suggest it may be an effect of thelarge difference in power between the two modes, that is, thelarge injection ratio masks the true response. Here we find theopposite case, with greater asymmetry in the non-lasing mode,which suggests new opportunities in injection applicationswith varying degrees of asymmetry. Furthermore, for bothparallel and orthogonal injections, the asymmetry becomesmore pronounced by increasing the SL bias current due tocurrent and temperature dependences of the enhancementlinewidth factor α [21].

In summary, the optical injection locking of two orthogonallinear polarization modes are studied in a single-transversemode 1.3-μm-wavelength VCSEL with parallel and orthogo-nal polarized injected light. The experimental results show twosignatures of the injection locking response: the power of the

LAMOTHE et al.: OPTICAL INJECTION LOCKING OF POLARIZATION MODES 943

injected mode is enhanced, and depleted in the non-injectedmode. Optical injection locking of the non-lasing polarizationmode produces a complete polarization switching and thuscan be used to control the polarization of the VCSEL. Theeffect of the injection locking is reduced at higher currentsabove threshold of the slave VCSEL due to the increase in theratio of the number of internally-produced photons and thoseinjected. A rate equation model explains well the observedinjection locking maps and gives insight into the injectionlocking mechanism.

REFERENCES

[1] E. Koyama, “Recent advances in VCSEL photonics,” J. Lightw. Technol.,vol. 24, no. 12, pp. 4502–4513, Dec. 2006.

[2] E. K. Lau, L. J. Wong, and M. C. Wu, “Enhanced modulation character-istics of optical injection-locked lasers: A tutorial,” IEEE J. Sel. TopicsQuantum Electron., vol. 15, no. 3, pp. 618–633, May/Jun. 2009.

[3] R. Lang, “Injection locking properties of a semiconductor laser,” IEEEJ. Quantum Electron., vol. 18, no. 6, pp. 976–983, Jun. 1982.

[4] A. Hayat, A. Bacou, A. Risson, C. Mollier, V. Iakovlev, A. Sirbu,and E. Kapon, “Long wavelength VCSEL-by-VCSEL optical injec-tion locking,” IEEE Trans. Microw. Theory Tech., vol. 57, no. 7,pp. 1850–1858, Jul. 2009.

[5] L. Chrostowski, B. Faraji, W. Hofmann, M.-C. Amann, S. Wieczorek,and W. W. Chow, “40 GHz bandwidth and 64 GHz resonance frequencyin injection-locked 1.55 μm VCSELs,” IEEE J. Sel. Topics QuantumElectron., vol. 13, no. 5, pp. 1200–1208, Sep./Oct. 2007.

[6] B. Nakarmi, M. Rakib-Uddin, and Y. H. Won, “Realization of all-optical digital comparator using single mode Fabry–Pérot laser diodes,”J. Lightw. Technol., vol. 29, no. 19, pp. 3015–3021, Oct. 1, 2011.

[7] Z. G. Pan, S. Jiang, and M. Dagenais, “Optical injection inducedpolarization bistability in vertical-cavity surface-emitting lasers,” Appl.Phys. Lett., vol. 63, no. 22, pp. 2999–3001, 1993.

[8] K. Panajotov, I. Gatare, A. Valle, H. Thienpont, and M. Sciamanna,“Polarization- and transverse-mode dynamics in optically injected andgain-switched vertical-cavity surface-emitting lasers,” IEEE J. QuantumElectron., vol. 45, no. 11, pp. 1473–1481, Nov. 2009.

[9] I. Gatare, M. Sciamanna, J. Buesa, H. Thienpont, and K. Panajotov,“Nonlinear dynamics accompanying polarization switching in vertical-cavity surface-emitting lasers with orthogonal optical injection,” Appl.Phys. Lett., vol. 88, no. 10, pp. 101–106, 2006.

[10] A. Hurtado, I. D. Henning, and J. Adams, “Two-wavelength switchingwith a 1550 nm VCSEL under single orthogonal optical injection,”IEEE J. Sel. Topics Quantum Electron., vol. 14, no. 13, pp. 911–917,May/Jun. 2008.

[11] A. Hurtado, A. Quirce, A. Valle, L. Pesquera, and M. J. Adams, “Non-linear dynamics induced by parallel and orthogonal optical injection in1550 nm vertical-cavity surface-emitting lasers (VCSELs),” Opt. Exp.,vol. 18, no. 9, pp. 9423–9426, 2010.

[12] R. Michalzik, VCSELs Fundamentals, Technology, and Applicationsof Vertical-Cavity Surface-Emitting Lasers. Berlin, Germany: Springer-Verlag, 2013.

[13] A. Sirbu, I. Iakovlev, A. Mereuta, A. Caliman, C. Suruceanu, andE. Kapon, “Wafer-fused heterostructures: Application to vertical-cavitysurface-emitting lasers emitting in the 1310 nm band,” Semicond. Sci.Technol., vol. 26, no. 1, p. 014016, 2011.

[14] E. Lamothe, “Analysis and control of optical modes in VCSELs andVCSEL-arrays,” Ph.D. dissertation, EPFL, Lausanne, Switzerland, 2013.

[15] S. F. Yu, Analysis and Design of Vertical Cavity Surface Emitting Lasers.New York, NY, USA: Wiley, 2003.

[16] M. P. van Exter, R. F. M. Hendriks, and J. P. Woerdman, “Physicalinsight into the polarization dynamics of semiconductor vertical-cavitylasers,” Phys. Rev. A, vol. 57, no. 3, pp. 2080–2090, 1998.

[17] M. Nizette, M. Sciamanna, I. Gatare, H. Thienpont, and K. Panajotov,“Dynamics of vertical-cavity surface-emitting lasers with optical injec-tion: A two-mode model approach,” J. Opt. Soc. Amer. B, vol. 26, no. 8,pp. 1603–1613, 2009.

[18] L. A. Coldren and S. W. Corzine, Diode Lasers and Photonics IntegratedCircuits. New York, NY, USA: Wiley, 1995.

[19] N. Schunk and K. Petermann, “Noise analysis of injection-lockedsemiconductor injection lasers,” IEEE J. Quantum Electron., vol. 22,no. 5, pp. 642–650, May 1986.

[20] S. Bhooplapur and P. Delfyett, “Characterization of the phase andamplitude modulation of injection-locked VCSELs at 1550 nm usingcoherent optical demodulation,” IEEE J. Sel. Topics Quantum Electron.,vol. 19, no. 6, p. 1702408, Nov./Dec. 2013.

[21] H. D. Summers, P. Dowd, I. H. White, and M. R. T. Tan, “Calculationof differential gain and linewidth enhancement factor in 980-nm InGaAsvertical-cavity surface-emitting lasers,” IEEE Photon. Technol. Lett.,vol. 7, no. 7, pp. 736–738, Jul. 1995.

Elodie Lamothe received the M.Sc. degree in microtechnology sciencesfrom the Swiss Federal Institute of Technology, Lausanne, Switzerland, in2007, where she is currently pursuing the Ph.D. degree in photonics with theLaboratory of Physics of Nanostructures. Her thesis research focuses on themode analysis and control of single-aperture VCSELs and VCSEL-arrays.

Christopher M. Long received the B.S. degree in electrical engineeringand physics from Kansas State University, Manhattan, KS, USA, in 2002,and the M.Sc. and Ph.D. degrees in electrical engineering from the Uni-versity of Illinois, Urbana, IL, USA, in 2005 and 2008, respectively. Hisdissertation work was to fabricate and characterize electrically injectablephotonic crystal emitters. He was a Post-Doctoral Researcher in ultrafastoptics with Purdue University, West Lafayette, IN, USA, from 2009 to 2011.He is currently researching VCSELs with the Swiss Federal Institute ofTechnology, Lausanne, Switzerland. His research interests include fabricationand characterization of photonic devices, optical injection of lasers, andapplications of optical pulse shaping for microwave photonics.

Andrei Caliman received the M.S. degree in physics and solid state elec-tronics from Moldova State University, Chisinau, Moldova, in 1983, andpostgraduate courses in solid state electronics from Technical University ofMoldova, Chisinau. He joined the Laboratory of Physics of Nanostructures,Swiss Federal Institute of Technology, Lausanne, Switzerland, in 2006, as anEngineer and a Scientist and he is involved in development and processing ofdifferent types of wafer fused long wavelength VCSELs, VCSEL arrays andVECSELs.

Vladimir Iakovlev received the M.S. degree in microelectronics from theTechnical University of Moldova, Chisinau, Moldova, in 1985, and the Ph.D.degree in optoelectronics from the Institute of Applied Sciences, Chisinau,Russia, in 1985. He was involved in research in the field of semiconductorlight-emitting and laser diodes based on GaAs and InP in collaboration withthe Group of Alferov, Ioffe Institute, St. Petersburg, Russia. In 1997, hewas with the Swiss Federal Institute of Technology, Lausanne, Switzerland.In 2001, he was a Founding Member with BeamExpress SA, Lausanne,where he is currently in charge of design, test, and failure analysis oflong-wavelength vertical-cavity surface-emitting lasers (VCSELs). His currentresearch interests include research, development, and industrialization of longwavelength VCSELs.

Alexandru Mereuta is currently with BeamExpress SA, Lausanne, Switzer-land, to work on epitaxial growth, study and fabrication of long wavelengthvertical-cavity surface-emitting lasers (VCSELs). He was with the Laboratoryof Physics of Nanostructures, Swiss Federal Institute of Technology, Lau-sanne, and involved in epitaxial growth and development of new materialsand VCSEL structures. From 1990 to 2001, he was a Research Engineer andScientist with the CNRS Laboratoire de Photonique et de Nanostructures,France, France Telecom’s Laboratoire de Bagneux and the OptoelectronicsLaboratory, Technical University of Moldova, Chisinau, Moldova, where hewas involved in design, epitaxial growth, study and development of GaAs andInP-based QW and QD structures, laser diodes and VCSELs. He received thePh.D. degree from the Institute of Applied Physics, Chisinau, in 1993.

944 IEEE JOURNAL OF QUANTUM ELECTRONICS, VOL. 49, NO. 11, NOVEMBER 2013

Alexei Sirbu received the Ph.D. and Dr.Hab. degrees from the Institute ofApplied Sciences, Chisinau, Russia, in 1979 and 1991, respectively. He iscurrently a Senior Scientist with the Laboratory of Physics of Nanostructures,Swiss Federal Institute of Technology, Lausanne, Switzerland. He workson wafer fused vertical-cavity surface-emitting lasers (VCSELs) and othervertical cavity photonic devices and applications. He contributed to firstdemonstrations of tunable VCSELs, electrically pumped VCSELs emittingin 1310-nm and 1550-nm bands and double-fused, full 2-inch VCSEL waferfabrication processes. He has published more than 100 papers and ten patentson optoelectronics devices and fabrication methods.

Grigore Suruceanu received the M.S. degree in physics of semiconductordevices from the State University of Moldova, Chisinau, Moldova, in 1983.Since 1989, he has been with the research and development of GaAs and InP-based lightemitting laser diodes and optoelectronics assemblies with the groupof researches leaded by Dr. Sirbu at the Technical University of Moldova,Chisinau. In 2000, he was with the group of Prof. Kapon in the field of long-wavelength vertical-cavity surface-emitting lasers. In 2001, he was one ofthe founding team members of BeamExpress SA, Lausanne, Switzerland. Heis currently the Product Engineering Manager with BeamExpress SA. He isresponsible for the industrialization program of the long-wavelength VCSELproducts and is involved in the design/characterization of VCSEL-basedoptoelectronic assemblies. He holds four patents in the field of semiconductorlasers and also industrial applications of high power lasers.

Eli Kapon received the Ph.D. degree in physics from Tel Aviv University,Tel Aviv, Israel, in 1982. He was a Chaim Weizmann Research Fellowwith the California Institute of Technology, Pasadena, CA, USA, wherehe was involved mainly in phase-locked arrays of semiconductor lasers.From 1984 to 1993, he was with Bellcore, Piscataway, NJ, USA, first asa Technical Staff Member, before becoming a District Manager in 1989.He was involved in integrated optics in III–V compounds and in low-dimensional semiconductor nanostructures, particularly quantum wires andquantum dots. He managed the Quantum Structures District from 1989 to1992, and the Integrated Optoelectronics District from 1992 to 1993, atBellcore. In 1993, he was with the Physics Department, Swiss FederalInstitute of Technology, Lausanne, Switzerland, as a Professor, where heheaded the Laboratory of Physics of Nanostructures. From 1999 to 2000,he was a Sackler Scholar with the Mortimer and Raymond Sackler Instituteof Advanced Studies, Tel Aviv University. He helped establish the Tel AvivUniversity Center for Nanoscience and Nanotechnology and served as itsfirst Director from 2000 to 2002. In 2001, he founded the startup companyBeamExpress SA, Lausanne, where he has been the Chief Scientist. He isthe author or co-author of more than 300 journal articles and editor of twobooks on semiconductor lasers. His current research interests include self-organization of nanostructures, optical properties and electron transport inlow-dimensional quantum structures, quantum wire and quantum dot lasers,semiconductor-based quantum photonics, and vertical cavity surface emittinglasers. He is a fellow of the Optical Society of America and the AmericanPhysical Society of America. He is a recipient of the 2007 Humboldt ResearchAward.