Coupled cavity designs on two-dimensional square lattice photonic crystal slabs were used to demonstrate optically pumped indium arsenide quantum dot photonic crystal lasers at room temperature. Threshold pump powers of 120 and 370 μW were observed for coupled cavities including two and four defect cavities defined in optimised photonic crystals

Chen, H.

Deppe, D. G.

Scherer, A.

Shchekin, O. B.

Yoshie, T.

English

Caltech Authors - Main

Disczrxsion: The frce-running SFDR of 84 dB/Hz’/’ is thc highest 
rcported to date for frcc-running long wavelength VCSELs, which is 
further enhanced by injection locking. The rclatively high RlN valucs 
observed arc possibly due to reflections from the VCSEL-fibre 
coupling lenses [9], which is still under investigation. Rcducing the 
optical reflections is expected to reduce the RlN and further increase 
the SFDR. 
The enhancement in the fundamental power is attributed to the 
increase of photon density and possibly differcntial gain, which 
enhance the clectrical-optical modulation efficiency. Similarly, with 
the increase of photon density and differential gain, the rcsoiiaiicc 
frequency is increased. A larger offset bctwccii the modulation and 
resonance frequencies reduces thc nonlincar distortion enhanced by the 
carricr-photon interaction, which in turn rcduccs the third-harmonic 
, distortion. 
Concli~sion: We have demonstrated that iiijcction locking improves 
the analogue performance of long wavelength VCSELs. We have 
found that injection locking can improve the modulation bandwidth 
by a factor of two and reduce modulation nonlinearities. The gain of 
the VCSEL RF link was improved due to an increase in modulation 
efficiency. Finally, the third-harmonic spur-free dynamic range was 
improved by 9 ~ B / H Z ~ / ~  to be 93 dB/HzZi3. This is the highest 
rcported SFDR for a long wavelength VCSEL. 
(ci) IEE 2002 
Electronics Letters Online No: 20020678 
DOI: I O .  104Y/e1:20020678 
L. Chrostowski, C.-H. Chang and C.J. Chang-Hasaain (De/iorttnetit of 
Electrical Engineering uncl Computer Science, Universitj, of 
Culifornia, Berkeley, CA, 94720, USA) 
12 June 2002 
References 
1 LIU, J.M., CHF.N, II.F., MENG, X.J., and SIMPSON, T.O.: ‘Modulation 
bandwidth, noise, and stability of a semiconductor laser subject to 
strong injection locking’, lEEE Photonicx Techno/. Lett., 1997, 9, (IO), 
pp. 1325-1327 
ANNOVAZZI-LODI, V. SCIRE, A,,  SOREL, M., 2U1d DONATI, S . :  ‘Dynamic 
bchavior and locking of a scmicoiiductor laser subjected to external 
injection’, IEEE J;  Qiranturn Electron., 1998, 34, (12), pp. 2350-2357 
3 CIIEN. J.,  RAM, R,J., and HELKEY. R.: ‘Linearity and third-order 
intennodtilation distortion in DFB semiconductor lasers’, IEEE 
JT Qzrtmtum Electron., 1999, 35, (8), pp. 1231-1237 
PAPPERT, S., SUN, C., ORAZI. R., and WEINER, T.: ‘Microwave fiber optic 
links for shipboard antenna applications’. Proc 2000 IEEE Int. Conf. 
Phased Array Systems and Technology, Dana Point, CA, USA, 
pp. 345-348 
LEh, II.L.T., DALAL, R.V, lIAivl, R.J. ,  and CHOQUETTE, K.D.: ‘Dynaiiiic range 
of vertical-cavity surfacc-emitting lascrs in multimode links’, IEEE 
Photonics Technol. Lett., 1999, 11, ( I  I) ,  pp. 1473-1475 
6 I’II’REK, I., TAKIG[JCIII, K., BLACK, K.A., IILJ, E L , ,  and BOWl.IlS, J.E.: 
‘Haimonic distortion in  I .55 pm vertical-cavity lasers’, /EEL 
Photonics Technol. Lett., 2000, 12, (12), pp. 1686-1688 
7 MENG, X..I., CHAU, T., and WU. M.C.: ‘Tmprovcd intrinsic dynamic 
distortions in dircctly modulated semiconductor lascrs by optical 
injection locking’, /EEE Trans. blicrow Theory Tech., 1999, 47, (7), 
pp. 1172-1 I76 
YUk,N, w., et d,:  ‘High-performancc 1.6 pm single-epitaxy top-emitting 
VCSEL‘, Electron. Lett., 2000, 36, (13), pp. 1121-1 123 
WAY, W.I., LIN, C., ZAH. C E ,  CURTIS, L., SPICEI1, I<., and YOUNG, W.C.: 
‘Multiplc-reflection-induced intensity noise studies in a lightwave system 
for multichannel AM-VSB television signal distribution’, IEEE 
Photonics Techno/. Lett., 1990, 2, ( 5 ) ,  pp. 360-362 
2 
4 
5 
8 
9 
Quantum dot photonic crystal lasers 
T. Yoshie, O.B. Shchekin, H. Chen, 
D.G. Deppe and A. Scherer 
Couplcd cavity designs on two-diincnsional sqiiarc laltice photonic 
crystal slabs were used to demonstratc optically pumped indium 
arsenide quantum dot photonic crystal lascrs at  room temperature. 
Threshold pump powers of 120 and 370 pW were observcd for 
coupled cavities including two and four defect cavities defined in 
optimiscd photonic crystals. 
Introduction: Photonic crystal (PC) [ I ,  21 planar cavities arc likely to 
form compact building blocks, which can bc iised in future integrated 
nanophotonic systems. Onc of the most notable charactcristics of PC 
cavities is that thc inode profile and the quality (Q) factors are 
geoiiictrically controlled and can be designed. Using simple defect 
cavity dcsigns, the first photonic crystal lascrs we12 reported [3] on 
InGaAsP multi-quantum well (QW) structures several ycars ago. 
Quantum dot (QD)-PC lascrs, however, have bccn more difficult 
deviccs to construct due to much lower availablc gain f‘rom QD 
material [4, 51. Thc smaller gain results not only from a lower total 
volume of actively emitling material but also from variations in the 
spatial locality of QDs as well as inhomogeneous emission broad- 
ening. These effccts result in a siiiallcr number of QDs contributing to 
the gain in a resonance as the Q factor is increased. 
Our approach to address these issues is to use high Q cavities with 
relatively larger mock volumes. In this Letter, we dcscribc siinplc 
designs of couplcd cavities in square lattice photonic crystals and 
demonstrate laser operation from such quantum dot photonic crystal 
(QD-PC) cavities. 
Designs; We start by using square lattice dcl‘cct cavities since their 
predicted modc volumes arc generally largcr due to the smaller 
bandgap. To increase thc mode volume we analysed couplcd two- 
dcfect cavity structures with a three-dimensional finite difference 
time domain (3D-FDTD) model. Thc analysed two-defect cavities 
wcre located two latticc constants (u)  apart from each other to form 
one coupled cavity mode in a two-dimensional (2D) square lattice PC 
slab with 11 by 13 latticc periods surrounding the cavities. The 
rnodellcd photonic crystal slab geometry had a thickness ( d )  of 
0.4.51, hole radii ( r )  of 0.380 and a semiconductor rcfractivc index of 
3.4. Fig. I shows the ainplitudc profile of the electric field in the 
centre of thc slab. Ryu et a/. [6] previously classified the mode from 
such a defect cavity as a whispering gallery mode. The electric field 
is vertical to the hole cylinder axis in the middle of the slab. The 
calculated vertical and thc lateral Q factors (QL and ell) of the 
coupled cavity dcviccs are 9800 and 24000, respcctivcly, and 
the mode voluiiic (V= J(i:E’)/inax(i:E’) dr3) is I .  I3(i/n)’. Single 
defect cavities with similar geometries exhibit values of 8500, 26600, 
and 0.78(A/n)’, respectively. Two-dcfcct couplcd cavitics therefore 
increasc the mode volume by 50% with similar Qs, 
Fig. 1 hnplitntle profile of electric field on niido‘lc. o / P C  cavity .slrrh of’ 
two-tl<f&ct cavities 
Frequency a / A ,  0.3 15. Ratios of d /u  and Y / U  are 0.45 and 0.38, respectively 
Structure may be clear in Pig. 20 
Experiment; Five stacked self-assemblcd InAs QD layers were grown 
by molecular beam epitaxy to form tlic active gain material. Thc QD 
density in our samples is 5 x 10“’/cm2 and thc QD laycrs were 
separated by 30 nm GaAs layers. Alo.zCalJ,xAs is used for cladding 
layers to form thin slab waveguides, which are deposited on an 800 nm 
Alli,04Gao,04As sacrificial layer on a top of GaAs substratc. To define 
200 nm-thick 2D-PC slab cavities, electron-beam lithography, 
chemically assisted ion-beam etching, oxidation of Alo,94Gao,l,4As 
layer, and wet ctching of AIO,y layer wcrc performed. The detailed 
fabrication steps can be found clscwhere [4, 51. Many geomctrics of 
single-, two-, and four-defect coupled cavitics were fabricated within 
ELECTRONICS LETTERS 15th August 2002 Vol. 38 No. 17 967 
photonic crystals with lattice sizes of 31 x 31, 31 x 33, and 33 x 33, 
respcctivcly. Figs. 2a and h show typical scanning elcctron microscope 
images of two-coupled and four-coupled cavities, respectivcly. 
? 
m - 
0 
Lo 
.- 
Fig. 2 Coupled ciivities consisting of two- and /birr-defect ciivities in 
two-dimensional .sqzrare-liittice PCs 
u Two-defect cavitics 
b Four-defect cavities 
Lattice spacing of cach squarc lattice and !./a ratios arc 400 nni and 0.34, and 
420 nni and 0.38 for structures in Figs. 2a and h, respectivcly 
Twenty rianosecond pimping pulses with 2.86% duty cycle from a 
780 nm scmiconductor laser were used to measure luminescence 
spectra and L (pump power)-L (collccted resonance power) curve. 
The pumping beam diameter was varicd up to 4 pin. 
I lb0  11’50 l i00 1i50 Id00 1&0 1400 
A ,  nm 
Fig. 4 Luminescence spectra t u l m  frotn ,foiir-coupled PC cavity ut room 
teinp”ure by short opticul pulse ~~i in ip ing  
(a) below thrcshold, pump power = 140 LIW 
(b) closc to thrcshold, pump power = 250 pW 
(c) above thrcsholtl, iiuinp powcr = 990 1tW 
Results: Fig. 3 shows two L-L curves taken from two- and four-defect 
coupled cavities. Each of these cavities exhibits distinct thrcshold and 
linear increase in output power above threshold. Threshold pump 
powers of 120 and 370 p W  are measured for two- and four-defect 
coupled cavitics, respectively. Fig. 4 shows lumincscence spcctra from 
a four-defect coupled cavity. Below thrcshold (Fig. 4u), the resonance 
cannot bc clearly observed. Close to threshold: nonlinear 
amplification of emission is sccn (Fig. 40). Above threshold, tlic 
rcsonance intensity incrcascs significantly. The lasing wavelcngth of 
1328 nm matches thc ground statc emission of the QDs. The photonic 
crystal geomctry of a/A=0.316 in this lascr also matchcs the 
analysed mode frequency of two-defect coupled cavities. Spectral 
line widths decreascd from 1 to 2 nm (below threshold) to less 
than 0.2 nm (above thrcshold). The combination o f  distinct threshold 
in the L-L curves and line width narrowing both indicate that thc 
cavities are indeed lasing. For tw-o-defect coupled cavities, the 
resonance was measured at u/l.=0.3, which is s n i a k r  than the 
simulated valuc since thc experimental slab thickncss is largcr and 
thc hole diameter is smaller than modelled. Single defect cavities did 
not lase in our experiments, probably duc to a lack of sufficient gain 
from the QDs. 
800 
600 z 
; 
L 
Cl  
8 
2 400 
:: 
E 
U 
a, 
0 
I 
- 
200. 
0 
/ 
/ 
/ 
/ 
p 
/ 
/ 
/ 
/ 
/ 
I 
/ 
I 
/ 
/ 
/ 
I 
/ 
I 
6 c O !  
/ 
0 i  / I I 1 I I I 
0 200 400 600 800 1000 1200 
pump power LIW 
Fig. 3 Pump power dependence of collected i esonunce power from 
coupled PC cavities 
PC cavity consisting of two-coupled defcct cavities 
PC cavity consisting of four-coupled dcfcct cavities 
Concl~aion: Lasing was demonstrated from sclf-assembled indium 
arsenidc quantum dots included in photonic crystal coupled 
cavities. Two- and four-defect cavities, which were dcsigned to 
control the availablc gain volume, were found to rctain high 
quality factors. Thc cavity rcsonance showed clear threshold beha- 
viour in the optically pumped L-L curvcs and line width narrowing 
was obscrved. 
Acknowledgments ’ The authors greatly appreciate valuable discus- 
sions with and encouragement from M. LonEar and J. VuEkoviC. This 
hork was supportcd by the NSF under Grants ECS-9912039 and 
DMR-0 103 134, thc AFOSR under F49620-0 1-1 -0497, and by 
DARPA under MDA972-00-1-0019. 
6 LEE 2002 
Electronics Letters Online No: 20020650 
DOI: 10. 1049ie1:20020650 
T. Yoshic and A. Schercr (Depurtnzent of Electrical Engineering, 
C a l i j h i a  Ii~slitirte of Teclznology, Pusudenn, CA, 91 125-9300, USA) 
O.B. Shcheltin, H. Chen and D.G. Deppe (Microelectronics Research 
Cenfei: Department o/ Electricul and Cornpzrter Engineering, The 
University of Texas ut Austin, TX, 78712-1084, USA) 
11 June 2002 
References 
1 
2 
3 
YABLONOVITCH, E.: ‘Inhibited spontaneous cmission in solid-state physics 
and electronics’, Phys. Rev Lett., 1987, 58, pp, 2059-2062 
JOHN, s.: ‘Strong localization of photons in certain disordered dielectric 
supcrlattices’, Phys. Rev. Lett., 1987, 58, pp. 2486-2489 
PAINTER, O., LEI;, R.K., SCHHRI:I<, A,, YARLV, A., O’RRIEN, J.U., DAPKUS, PD., 
and KIM, I.: ‘Two-dimensional photonic band-gap defect mode laser’, 
Science, 1999, 284, pp. 1819-1821 
4 yostiik, T., SCIIERER, A,, CIIEN, H., IIUFFAKER, D., and DEPPE, D.: ‘Optical 
characterization of two-dimensional photonic crystal cavities with indium 
arsenide quantum dot cmitters’, Ap1~1. P h p .  Lett., 2001, 79, pp. 114-1 16 
YOSHIE, T,, VUCKO\rI<:, J., SCHBRI(R, A,, CIIEN, H., and DEPPE, D.: ‘High 
quality two-dimensional photonic crystal slab cavities’, Appl. Phys. Lett., 
2001, 79, pp. 42894291 
RYU, II.Y., KIM, S.tI., PARK, H.G., IIWANG, J.K., LEE, Y.H., and KIM, J.S.: 
‘Square-lattice photonic band-gap single-cell lascr operating in the 
lowest-ordcr whispering gallery mode’, Appl. Phys. Lett., 2002, 80, 
pp. 3883-3885 
5 
6 
968 ELECTRONICS LETTERS 15th August 2002 Vol. 38 No. 17 


Quantum dot photonic crystal lasers

Inhibited spontaneous cmission in solid-state physics

http://authors.library.caltech.edu/738/1/YOSel02.pdf

Quantum dot photonic crystal lasers

Abstract

Similar works

Full text

Available Versions

Caltech Authors - Main