Integrated photonic systems require efficient, compact, and broadband solutions for strong light coupling into and out of optical waveguides. The present work investigates an efficient optical power transferring the problem between optical waveguides having different widths of in/out terminals. We propose a considerably practical and feasible concept to implement and design an optical coupler by introducing gradually index modulation to the coupler section. The index profile of the coupler section is modulated with a Gaussian function by the help of striped waveguides. The effective medium theory is used to replace the original spatially varying index profile with dielectric stripes of a finite length/width having a constant effective refractive index. 2D and 3D finite-difference time-domain analyzes are utilized to investigate the sampling effect of the designed optical coupler and to determine the parameters that play a crucial role in enhancing the optical power transfer performance. Comparing the coupling performance of conventional benchmark adiabatic and butt couplers with the designed striped waveguide coupler, the corresponding coupling efficiency increases from approximately 30% to 95% over a wide frequency interval. In addition, to realize the realistic optical coupler appropriate to integrated photonic applications, the proposed structure is numerically designed on a silicon-on-insulator wafer. The implemented SOI platform based optical coupler operates in the telecom wavelength regime (λ = 1.55 μm), and the dimensions of the striped coupler are kept as 9.77 μm (along the transverse to propagation direction) and 7.69 μm (along the propagation direction) where the unit distance is fixed to be 465 nm. Finally, to demonstrate the operating design principle, the microwave experiments are conducted and the spot size conversion ratio as high as 7.1:1 is measured, whereas a coupling efficiency over 60% in the frequency range of 5.0–16.0 GHz has been also demonstrated.

1.
Y.
Xu
,
R. K.
Lee
, and
A.
Yariv
,
Opt. Lett.
25
,
755
(
2000
).
2.
N.
Tzoar
and
R.
Pascone
,
J. Opt. Soc. Am.
71
,
1107
(
1981
).
3.
D. W.
Prather
,
J.
Murakowski
,
S.
Shi
,
S.
Venkataraman
,
A.
Sharkawy
,
C.
Chen
, and
D.
Pustai
,
Opt. Lett.
27
,
1601
(
2002
).
4.
A.
Mekis
and
J. D.
Joannopoulos
,
J. Light Technol.
19
,
861
(
2001
).
5.
P.
Lalanne
and
A.
Talneau
,
Opt. Express
10
,
354
(
2002
).
6.
M.
Palamaru
and
P.
Lalanne
,
Appl. Phys. Lett.
78
,
1466
(
2001
).
7.
E.
Khoo
,
A.
Liu
, and
J.
Wu
,
Opt. Express
13
,
7748
(
2005
).
8.
H.
Kurt
and
D. S.
Citrin
,
Opt. Express
15
,
1240
(
2007
).
9.
H.
Kurt
,
E.
Colak
,
O.
Cakmak
,
H.
Caglayan
, and
E.
Ozbay
,
Appl. Phys. Lett.
93
,
171108
(
2008
).
10.
B.
Vasi
,
G.
Isic
,
R.
Gajic
, and
K.
Hingerl
,
Opt. Express
18
,
20321
(
2010
).
11.
M.
Turduev
,
B. B.
Oner
,
I. H.
Giden
, and
H.
Kurt
,
J. Opt. Soc. Am. B
30
,
1569
(
2013
).
12.
M.
Turduev
,
I. H.
Giden
, and
H.
Kurt
,
Opt. Commun.
339
,
22
(
2015
).
13.
M.
Turduev
,
Z.
Hayran
, and
H.
Kurt
,
J. Appl. Phys.
120
,
243102
(
2016
).
14.
H.
Kurt
and
D. S.
Citrin
,
IEEE Photonics Technol. Lett.
19
,
1532
(
2007
).
15.
U.
Levy
,
M.
Abashin
,
K.
Ikeda
,
A.
Krishnamoorthy
,
J.
Cunningham
, and
Y.
Fainman
,
Phys. Rev. Lett.
98
,
243901
(
2007
).
16.
A. O.
Cakmak
,
E.
Colak
,
H.
Caglayan
,
H.
Kurt
, and
E.
Ozbay
,
J. Appl. Phys.
105
,
103708
(
2009
).
17.
H. T.
Chien
,
C.
Lee
,
H. K.
Chiu
,
K. C.
Hsu
,
C. C.
Chen
,
J. A. A.
Ho
, and
C.
Chou
,
J. Light Technol.
27
,
2570
(
2009
).
18.
H.
Kurt
,
B. B.
Oner
,
M.
Turduev
, and
I. H.
Giden
,
Opt. Express
20
,
22018
(
2012
).
19.
M.
Grajower
,
G. M.
Lerman
,
I.
Goykhman
,
B.
Desiatov
,
A.
Yanai
,
D. R.
Smith
, and
U.
Levy
,
Opt. Lett.
38
,
3492
(
2013
).
20.
L. H.
Gabrielli
and
M.
Lipson
,
Opt. Express
19
,
20122
(
2011
).
21.
A.
Di Falco
,
S. C.
Kehr
, and
U.
Leonhardt
,
Opt. Express
19
,
5156
(
2011
).
22.
T. C.
Choy
,
Effective Medium Theory: Principles and Applications
(
Oxford University Press
,
2015
).
23.
H.
Melkonyan
and
M. S.
Dahlem
, in
Photonics Global Conference (PGC)
,
Singapore
,
13–16 December 2012
.
24.
A. F.
Oskooi
,
D.
Roundy
,
M.
Ibanescu
,
P.
Bermel
,
J. D.
Joannopoulos
, and
S. G.
Johnson
,
Comput. Phys. Commun.
181
,
687
(
2010
).
25.
J. P.
Berenger
,
J. Comput. Phys.
114
,
185
(
1994
).
26.
B. E. A.
Saleh
and
M. C.
Teich
,
Fundamentals of Photonics
(
Wiley
,
2007
).
27.
Lumerical Solutions, Inc., see http://www.lumerical.com/tcad-products/fdtd/ for a commercial-grade simulator called Lumerical Finite Difference Time Domain (FDTD) Solutions. (last accessed 30 May
2017
).
28.
T. D.
Happ
,
M.
Kamp
, and
A.
Forchel
,
Opt. Lett.
26
,
1102
(
2001
).
29.
A.
Talneau
,
P.
Lalanne
,
M.
Agio
, and
C. M.
Soukoulis
,
Opt. Lett.
27
,
1522
(
2002
).
30.
R.
Orobtchouk
,
A.
Layadi
,
H.
Gualous
,
D.
Pascal
,
A.
Koster
, and
S.
Laval
,
Appl. Opt.
39
,
5773
(
2000
).
31.
S.
Lardenois
,
D.
Pascal
,
L.
Vivien
,
E.
Cassan
,
S.
Laval
,
R.
Orobtchouk
,
M.
Heitzmann
,
N.
Bouzaida
, and
L.
Mollard
,
Opt. Lett.
28
,
1150
(
2003
).
32.
M. I.
Kotlyar
,
Y. R.
Triandaphilov
,
A.
Kovalev
,
V.
Soifer
,
M. V.
Kotlyar
, and
L.
O'Faolain
,
Appl. Opt.
48
,
3722
(
2009
).
33.
H.
Chien
and
C. C.
Chen
,
Opt. Express
14
,
10759
(
2006
).
34.
N.
Yogesh
and
V.
Subramanian
,
Prog. Electromagn. Res.
129
,
51
(
2012
).
35.
B.
Bahari
and
M. S.
Abrishamian
,
J. Opt.
15
,
125502
(
2013
).
36.
Z.
Lu
,
J. A.
Murakowski
,
C. A.
Schuetz
,
S.
Shi
,
G. J.
Schneider
, and
D. W.
Prather
,
Phys. Rev. Lett.
95
,
153901
(
2005
).
You do not currently have access to this content.