Download Mode Conversion/Splitting by Optical Analogy of Multistate

JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 28, NO. 24, DECEMBER 15, 2010
3529
Mode Conversion/Splitting by Optical Analogy of
Multistate Stimulated Raman Adiabatic Passage in
Multimode Waveguides
Shuo-Yen Tseng and Ming-Chan Wu
Abstract—We propose and describe mode converter/splitter
based on optical analogy of multistate stimulated Raman adiabatic
passage in multimode waveguides. Computer-generated planar
holograms are used to implement the coupling coefficients that
mimic the optical pulses used in the transfer among quantum
states of atoms and molecules. The mode coupling properties
in multimode waveguides are analyzed using the coupled-mode
theory and shown to resemble the multistate stimulated Raman
adiabatic passage process. Key features of multistate systems are
illustrated with theoretical calculations and numerical examples.
Mode converter and splitter are designed based on the theoretical
analysis and verified using beam propagation simulations.
Index Terms—Coupled mode analysis, gratings, multimode
waveguide, optical beam splitting, optical planar waveguides.
I. INTRODUCTION
I
NTEGRATED optical devices are important elements for
the development of all-optical networks. One important
class of devices is the mode conversion and mode splitting
devices. They can be used for mode-division multiplexing
in optical interconnects and short-distance communications
[1]. For long-distance communications, they can be used to
perform key functions such as filtering, power splittering, and
multiplexing [2]–[4]. For most of these devices, mode coupling
is mediated by system perturbations resulting from periodic
index variations, and their characteristics are highly sensitive to
the device parameters. More tolerant coupling schemes would
be desirable in terms of processing cost reduction.
Recently, similarities between quantum mechanics and wave
optics have been exploited in the studies of a rich variety of integrated optical devices [5]. Of particular interest is the optical
analogy of the stimulated Raman adiabatic passage (STIRAP)
phenomena [6]. STIRAP refers to the adiabatic transfer of population between two energy levels in a three-level system via
Manuscript received August 10, 2010; revised September 15, 2010; accepted
October 21, 2010. Date of publication October 28, 2010; date of current version
December 03, 2010. This work was supported in part by the National Science
Council of Taiwan under Contract NSC98-2221-E-006-016.
S.-Y. Tseng is with the Department of Electro-Optical Engineering, National
Cheng Kung University, Tainan 701, Taiwan, and the Advanced Optoelectronics Technology Center, National Cheng Kung University, Tainan 701,
Taiwan (e-mail: [email protected]).
M.-C. Wu is with the Department of Electro-Optical Engineering, National
Cheng Kung University, Tainan 701, Taiwan.
Color versions of one or more of the figures in this paper are available online
at http://ieeexplore.ieee.org.
Digital Object Identifier 10.1109/JLT.2010.2089785
two delayed optical pulses, and it is a robust process insensitive to the precise pulse shapes. In integrated optics, such systems can be mimicked by a coupled three-waveguides structure
with spatially varying coupling coefficients for adiabatic power
exchange between two waveguides [7]–[9]. Similar schemes
have been considered on three-moded waveguide systems with
two spatial gratings for slow light propagation [10], [11]. A
three-moded adiabatic mode converter based on optical analogy
of STIRAP has also been proposed recently [12]. The remarkable feature of such systems is their high tolerance to system
parameter variations, because the process is based on adiabatic
evolution of a system eigenmode. This feature greatly relaxes
the demands on geometrical control as required in conventional
devices.
Due to the complexity of optical networks, devices involving
guided modes need to be considered. As shown
multiple
in the literature [13], [14], the extension of STIRAP to multistate
systems is nontrivial. An important feature of the three-moded
STIRAP is that the intermediate mode is not populated during
the conversion, owing to the existence of the dark mode which
does not involve the intermediate mode [12]. In a multimode
system, however, such a dark mode does not exist [13],
and some intermediate modes may acquire significant populations during the conversion. The coupling dynamics are more
complex and provides richer physics for us to explore.
In this paper, we study optical mode conversion/splitting
based on the multistate STIRAP process. We consider a
modes coupled
multimode waveguide structure with
by multiplexed long-period gratings with variable coupling
strengths. Mode coupling in multimode waveguides can be
achieved with tilted gratings [4]. In this work, the gratings are
calculated as computer-generated planar holograms (CGPHs)
using our previously developed algorithm [15] to create optical
analogies of the multistate STIRAP. Coupled-mode theory
is used to analyze the mode coupling properties of these devices and to show their resemblance to the multistate STIRAP
process. The key difference between three-moded STIRAP
and multistate STIRAP is discussed and illustrated using
beam propagation simulations. Mode converters/splitters are
designed using optical analogies of the multistate STIRAP.
II. THEORETICAL ANALYSIS
We consider a waveguide supporting
distinct forward-propagating modes and use the coupled-mode theory
[16] to analyze the effect of CGPHs on the mode evolution
in the waveguide. The CGPHs are multiplexed long-period
0733-8724/$26.00 © 2010 IEEE
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JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 28, NO. 24, DECEMBER 15, 2010
Fig. 1. Schematic of the chainwise-connected system providing the quantum
is the
analogy of light transfer in a multimode waveguide with CGPH. Rabi frequency of the pulse coupling states jmi and jm
i.
+1
gratings that couple the propagating modes depending on
the grating shapes and periodicity [15]. We also make the
usual assumptions that the waveguide is single-moded in the
transverse direction, and the effective index method can be
used to separate the transverse and lateral components of
the electric field. In a -moded multimode waveguide with
of mode
CGPH, the evolution equation of mode amplitude
can be derived as
(1)
is the spatially varying coupling coefficient bewhere
tween modes
and
. Details of the derivation of (1) and
the calculation of coupling coefficients can be found in [17]. Assuming the CGPH only couples the nearest-neighboring modes,
a matrix form can be used for (1)
(2)
is a tri-diagonal matrix
where
..
.
..
.
..
.
..
.
..
.
..
.
..
.
(3)
, and denotes the transpose. The matrix
is Hermitian [15]. Replacing the spatial
variation with the temporal variation , (2)–(3) are used to
describe the probability amplitudes of the -state multilevel
STIRAP system using the Schrödinger equation
under
the rotating-wave approximation [13], in which
represents
the probability amplitudes of the states being populated, and
is the Rabi frequency of the pulse coupling states
and
. Throughout the paper,
is assumed to be
real and positive without loss of generality. The light transfer
among the
modes is equivalent to the chainwise-connected
system shown schematically in Fig. 1. As a result, the unique
features of STIRAP can be observed in a multimode waveguide
with CGPH.
We can solve for the eigenmodes of , which, under the
adiabatic condition (i.e.,
varies slowly with ), evolve
adiabatically without energy exchange among them. For the purto , an adiabatic
pose of adiabatic mode conversion from
mode , which is equal to
at the input and mode
at the
output, needs to exist. For the purpose of adiabatic mode splitting from
to
, and , an adiabatic mode , which is
equal to
at the input and modes
, and
at the output,
needs to exist. With the existence of these modes, the coupling
coefficients can be engineered to implement the mode conversion/splitting. Intuitively, for a transition from
to
via the
intermediate states, the pulse sequence (coupling coefficients)
coupling the states needs to be applied in a manner such that the
earlier the transition, the earlier the pulse arrives. In the STIRAP
process, the order of the pulse sequence is reversed: the later the
transition, the earlier the pulse arrives [6]. As will be shown in
the discussions below, this counterintuitive coupling scheme is
required for the STIRAP process. Based on literatures on multilevel systems [13], [18], we first briefly review three-moded
systems and then extend the analysis to -moded systems.
A. Three-Moded Waveguides
When
, the equation reduces to the one that describes
the three-moded adiabatic mode converter with modes
,
and . We briefly restate the main results from [12].
An adiabatic mode of with a zero eigenvalue can be found
as
(4)
When the eigenmode
is excited initially, the system will
remain in it if the coupling coefficients are varied slowly. From
(4), if the two variable coupling coefficients
and
are applied in a counterintuitive scheme, where
precedes
, then
approaches
at the input. If
is incident
in the waveguide, then the eigenmode
will
be excited, which corresponds to
of the unperturbed waveguide. At the output
, the eigenmode has adiabatically
evolved to
, corresponding to
of the unperturbed waveguide. As a result,
will exit the waveguide.
This is the dark mode that facilitates adiabatic conversion of
to
without populating .
We note that in a waveguide with number of modes
, an
optical analogy of STIRAP involving only three modes
,
and
can be implemented by two gratings coupling modes
and
for the conversion from
to
without populating . In the general case presented below, all modes are
involved, which represents an optical analogy of the multistate
STIRAP process.
B. N-Moded Waveguides
We only consider the case when
is odd because an adiabatic mode does not exist for
with an even
[13]. A zero
eigenvalue exists for with the corresponding adiabatic mode
[13], [18]
(5)
(6)
(7)
TSENG AND WU: MODE CONVERSION/SPLITTING BY OPTICAL ANALOGY
3531
Fig. 2. Cross-sectional schematic of the ridge waveguide structure used for the
device design and simulation.
where
is a normalization factor. It can be shown that if the
and
are arranged counterincoupling coefficients
tuitively (
precedes
), is equal to
at the input
at the output [13]. Hence, adiabatic mode conversion
and
to
can be achieved. All even modes are not popufrom
lated in the conversion as shown in (7). However, the intermediate odd modes are populated during the conversion. This is
STIRAP where the infundamentally different from the
termediate state is not involved in the dark mode shown in (4).
For example, the adiabatic mode for a five-moded waveguide
is
Fig. 3. Counterintuitive coupling scheme for mode conversion using optical
analogy of the three-moded STIRAP.
(8)
It is obvious that the even modes
and
are not involved
in the conversion. When the coupling coefficients
and
are arranged counterintuitively,
is equal to
at the input
and
at the output. Comparing (8) with (4), we observe that
the intermediate mode
is populated, and its population is
directly related to the ratios of
and
to
and
.
This offers us freedom in designing devices with mode splitting
functionalities as will be shown in the next section.
Fig. 4. (a) Calculated CGPH pattern to implement the counterintuitive coupling
coefficients in Fig. 3. (b) WA-BPM simulation of the mode conversion from
mode 5 to mode 1 using optical analogy of the three-moded STIRAP. Dashed
lines indicate the waveguide core.
III. DEVICE DESIGN AND SIMULATION
In this section, we design CGPHs on a five-moded waveguide
to implement multistate STIRAP for mode conversion/splitting.
A polymer ridge waveguide structure as shown in Fig. 2 is
chosen with the following design parameters: 3 m thick SiO
on a Si wafer for the bottom cladding layer, 2.4 m layer of
Cyclotene™ (BCB) for the core, the width of the waveguide
is 3 m, and the length of the waveguide is 50 mm. The refractive indexes of the layers are given in Fig. 2. The device is
designed at a wavelength of 1.55- m input wavelength and the
TE polarization. We use a finite-difference mode solver [19]
to verify that this waveguide geometry indeed supports five
guided modes. Subsequent analysis is performed on the two-dimensional (2-D) structure obtained using the effective index
method. The wide-angle beam propagation method (WA-BPM)
[20] is used for device simulations with discretization steps
m and
m.
A. Mode Conversion With
We first design a mode converter converting
to
using optical analogy of the three-moded STIRAP discussed
as the intermediate mode, we
in Section II.A. Choosing
design the CGPH with a maximum refractive index modulation
to implement the counterintuitive
of
coupling scheme between modes 1, 3 and 3, 5 as shown in
and
Fig. 3. The Gaussian shaped coupling coefficients
are chosen to mimic the optical pulses used in the transfer
among quantum states of atoms and molecules [6]. The exact
shape and parameter of the coupling coefficients are not critical
as long as the conditions for adiabatic evolution is satisfied [6],
[13]. Fig. 4(a) shows the calculated CGPH pattern with the
. The CGPH pattern
index modulation normalized to
is used as an effective index perturbation to the multimode
waveguide. Details of the CGPH calculation can be found in
[15].
as the input is
The WA-BPM simulation result using
shown in Fig. 4(b). Fig. 5 shows the power in each guided mode
along the propagation distance calculated by mode projection
is
using the WA-BPM results. As explained in Section II.A,
converted adiabatically to
with very little excitation of the
intermediate mode , and the even modes are not involved in
the conversion.
B. Mode Conversion With
Next, we design a mode converter using optical analogy of
the multistate STIRAP discussed in Section II.B and illustrate
system described above.
its key differences from the
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Fig. 5. Evolution of mode power in the waveguide obtained by mode projection
using the WA-BPM results in Fig. 4(b).
Fig. 6. Counterintuitive coupling scheme for mode conversion using optical
analogy of the five-moded STIRAP.
A CGPH with a maximum refractive index modulation of
is designed to implement the coupling
and
as shown in Fig. 6. The
coefficients
coupling coefficients are arranged in a way such that when
and
arises, the subsystem comprising all intermediate
modes is already dressed [14], [21]. Under this condition,
is coupled simultaneously to the intermediate modes, which
. In such a scheme, the odd intermediate
then couples to
modes can be suppressed by choosing large
and
for
is
reasons given below. As shown in (8), the population in
and
to
and
. When
related to the ratios of
, the population in
is much less than
and , and as a result, the population in
is suppressed
throughout the conversion. Large coupling coefficients would
correspond to large refractive index perturbations in the CGPH
design [15]. In the design shown in Fig. 6, we deliberately set
and
to be equal to
and
to show that the
is involved in the multistate STIRAP.
intermediate mode
The calculated CGPH pattern is shown in Fig. 7(a). Again, the
exact shapes of the coupling parameters are not critical for the
conversion.
JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 28, NO. 24, DECEMBER 15, 2010
Fig. 7. (a) Calculated CGPH pattern to implement the counterintuitive coupling
coefficients in Fig. 6. (b) WA-BPM simulation of the mode conversion from
mode 5 to mode 1 using optical analogy of the five-moded STIRAP. Dashed
lines indicate the waveguide core.
Fig. 8. Evolution of mode power in the waveguide obtained by mode projection
using the WA-BPM results in Fig. 7(b).
as the input is
The WA-BPM simulation result using
shown in Fig. 7(b). Fig. 8 shows the power in each guided mode
along the propagation distance. As explained in Section II.B,
is converted adiabatically to
. However, the adiabatic
mode used in the conversion involves
, which is excited in
the conversion process as shown clearly in the figure. The excitation of intermediate states might be detrimental for atomic
and molecular systems if the intermediate states have large
decay rates. In multimode waveguides, we can use it to our
advantage to perform mode splitting functionalities as shown
in the next subsection.
C. Mode Splitting With
Here, we illustrate mode splitting from
to
, and
. A CGPH with a maximum refractive index modulation of
is designed. The coupling coefficients
and
having the shape of the
are shown in Fig. 9, with
and
having
sum of two delayed Gaussian pulses, and
the shape of a Gaussian pulse. Their exact shapes can be found in
the literature [22]. Referring to (8), with such an arrangement,
TSENG AND WU: MODE CONVERSION/SPLITTING BY OPTICAL ANALOGY
3533
Fig. 11. Simulated output power in modes 1 and 5 as a function of CGPH etch
depth using mode 5 as the input to the mode converter.
Fig. 9. Counterintuitive coupling scheme for mode splitting using optical
analogy of the five-moded fractional STIRAP.
Fig. 10. Evolution of mode power in the mode splitter using WA-BPM
simulation.
at the input, corresponding to
; at the
output,
, corresponding to equal distribu, and . This is an analogy of the fractional
tions among
STIRAP (f-STIRAP) in which coherent atomic superpositions
are created [22]. The final state is determined by the vanishing
tails of the coupling coefficients, and the exact shapes of the coupling coefficients are not critical. By adjusting the ratios of the
coupling coefficients, the split ratios can be varied arbitrarily.
Using the coupling coefficients in Fig. 9, the power in each
as the
guided mode using the WA-BPM simulation with
is split into
input is shown in Fig. 10. As expected, the input
, and
at the output. This design example shows that
the optical analogy of f-STIRAP in multistate system can be
applied to mode splitting by choosing appropriate coupling coefficients. We note that beam splitting by f-STIRAP is recently
demonstrated using three coupled waveguides [23]. Our design
example extends the optical analogy of f-STIRAP to multistate
systems.
IV. DISCUSSION
The CGPH in Figs. 4(a) and 7(a) consists of multiplexed
long-period gratings with etch depth variations along the propa-
gation direction. The fabrication of binary CGPH as surface relief patterns with fixed etch depth has been reported elsewhere
[15], [24]. To fabricate the adiabatically varying etch depth in
the proposed devices, grayscale lithography, such as the one reported for the fabrication of three-dimensional adiabatic waveguide tapers [25], would be a possible choice, and it allows
wafer-scale processing of the devices.
From the analysis presented in the previous sections, the light
transfer characteristics among the guided modes in multimode
waveguides with properly designed CGPHs indeed resembles
the STIRAP phenomena. As a result, we expect the devices
to be robust against variations in the shapes of the designed
coupling coefficients due to fabrication imperfections since the
coupling coefficients are equivalent to the pulses considered
in the STIRAP process, which is proven to be robust against
pulse variations. Detailed analysis on the robustness of STIRAP
against pulse intensity variations and delays can be found in the
literature [6], [22]. Here, we present simulation results on the
variations of the mode conversion characteristics due to etch
depth variations of the CGPH pattern.
One of the main advantages of devices based on adiabatic
mode evolution, despite their relatively large sizes, is their large
fabrication tolerance. Using the mode converter introduced in
Section III.B, we analyze the robustness of the proposed devices
against fabrication errors. From the modal power evolution plot
shown in Fig. 8, it is clear that the device is robust against device length variations resulting from typical fabrications errors.
, is directly related to the
Errors in the CGPH etch depth,
effective index modulation, which in turn affects the coupling
coefficients. For the ridge waveguide structure in Fig. 2, the efand
follows an almost linear
fective index modulation
/nm as estirelation with a slope of
mated by the effective index method. In Fig. 11, using mode 5 as
the input to the mode converter, we simulate the power in modes
1 and 5 at the output as a function of etch depth. For a wide variation of over 300 nanometers, the device retains its mode conversion property very well. This robustness is expected due to the
adiabatic nature of the conversion process. On the other hand,
mode conversion devices relying on grating-assisted mode coupling, while being more compact than the proposed device, require stringent control of the etch depth.
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V. CONCLUSION
In conclusion, we have proposed optical mode converter/splitter using optical analogy of multistate STIRAP.
This scheme allows adiabatic mode conversion/splitting in
multimode waveguides without strict restrictions on the coupling parameters. Mode conversion using multistate STIRAP
would excite the intermediate modes, while the three-moded
STIRAP converts the modes without the excitation of the
intermediate mode. The properties of multistate STIRAP allow
for the design of mode splitters using optical analogy of the
fractional multistate STIRAP. The theoretical calculations are
verified with beam propagation simulations.
REFERENCES
[1] J. B. Park, D.-M. Yeo, and S.-Y. Shin, “Variable optical mode generator
in a multimode waveguide,” Photon. Technol. Lett., vol. 18, no. 20, pp.
2084–2086, 2006.
[2] J. M. Castro and D. F. Geraghty, “Demonstration of mode conversion
using antisymmetric waveguide Bragg gratings,” Opt. Exp., vol. 13, no.
11, pp. 4180–4184, 2005.
[3] J. M. Castro, D. F. Geraghty, S. Honkanen, C. M. Greiner, D. Iazikov,
and T. W. Mossberg, “Optical add-drop multiplexers based on the antisymmetric waveguide Bragg grating,” Appl. Opt., vol. 45, no. 6, pp.
1236–1243, 2006.
[4] K. S. Lee, “Mode coupling in tilted planar waveguide gratings,” Appl.
Opt., vol. 39, no. 33, pp. 6144–6149, 2000.
[5] S. Longhi, “Quantum-optical analogies using photonic structures,”
Laser & Photon. Rev., vol. 3, no. 3, pp. 243–161, 2009.
[6] K. Bergmann, H. Theuer, and B. W. Shore, “Coherent population
transfer among quantum states of atoms and molecules,” Rev. Mod.
Phys., vol. 70, no. 3, pp. 1003–1025, 1998.
[7] E. Paspalakis, “Adiabatic three-waveguide directional coupler,” Opt.
Commun., vol. 258, pp. 30–34, 2006.
[8] S. Longhi, “Adiabatic passage of light in coupled optical waveguides,”
Phys. Rev. E, vol. 73, no. 2, p. 026607, 2006.
[9] A. Salandrino, K. Makris, D. N. Christodoulides, Y. Lahini, Y. Silberberg, and R. Morandotti, “Analysis of a three-core adiabatic directional
coupler,” Opt. Commun., vol. 282, pp. 4524–4526, 2009.
[10] A. Yariv, “Frustration of Bragg reflection by cooperative dual-mode
interference: A new mode of optical propagation,” Opt. Lett., vol. 23,
no. 23, pp. 1835–1836, 1998.
[11] H.-C. Liu and A. Yariv, “Grating induced transparency (GIT) and the
dark mode in optical waveguides,” Opt. Express, vol. 17, no. 14, pp.
11710–11718, 2009.
[12] S.-Y. Tseng and M.-C. Wu, “Adiabatic mode conversion in multimode
waveguides using computer-generated planar holograms,” Photon.
Technol. Lett., vol. 22, no. 16, pp. 1211–1213, 2010.
[13] N. V. Vitanov, “Adiabatic population transfer by delayed laser pulsed
in multistate systems,” Phys. Rev. A, vol. 58, no. 3, pp. 2295–2309,
1998.
[14] G. D. Valle, M. Ornigotti, T. T. Fernandez, P. Laporta, S. Longhi, A.
Coppa, and V. Foglietti, “Adiabatic light transfer via dressed states in
optical waveguide arrays,” Appl. Phys. Lett., vol. 92, no. 1, p. 011106,
2008.
[15] S.-Y. Tseng, Y. Kim, C. J. K. Richardson, and J. Goldhar, “Implementation of discrete unitary transformations by multimode waveguide
holograms,” Appl. Opt., vol. 45, no. 20, pp. 4864–4872, 2006.
[16] D. Marcuse, Theory of Dielectric Optical Waveguides. San Diego,
CA: Academic, 1991.
[17] S.-Y. Tseng, C. Fuentes-Hernandez, D. Owens, and B. Kippelen, “Variable splitting ratio 2 2 MMI couplers using multimode waveguide
holograms,” Opt. Exp., vol. 15, no. 14, pp. 9015–9021, 2007.
[18] A. V. Smith, “Numerical studies of adiabatic population inversion in
multilevel systems,” J. Opt. Soc. Amer. B, vol. 9, no. 9, pp. 1543–1551,
1992.
[19] A. B. Fallahkhair, K. S. Li, and T. Murphy, “Vector finite difference
modesolver for anisotropic dielectric waveguides,” J. Lightw. Technol.,
vol. 26, no. 11, pp. 1423–1431, Nov. 2008.
[20] G. R. Hadley, “Wide-angle beam propagation using Padé approximation operators,” Opt. Lett., vol. 17, no. 20, pp. 1426–1428, 1992.
[21] N. V. Vitanov, B. W. Shore, and K. Bergmann, “Adiabatic population
transfer in multistate chains via dressed intermediate states,” Eur. Phys.
J. D, vol. 4, pp. 15–29, 1998.
[22] N. V. Vitanov, K.-A. Suominen, and K. Bergmann, “Creation of coherent atomic superpositions by fractional stimulated Raman adiabatic
passage,” J. Phys. B: At. Mol. Opt. Phys., vol. 32, pp. 4535–4546, 1999.
[23] F. Dreisow, M. Ornigotti, A. Szameit, M. Heinrich, R. Keil, S. Nolte,
A. Tünnermann, and S. Longhi, “Polychromatic beam splitting by fractional stimulated Raman adiabatic passage,” Appl. Phys. Lett., vol. 95,
no. 25, p. 261102, 2009.
[24] S.-Y. Tseng, S. Choi, and B. Kippelen, “Variable-ratio power splitters
using computer-generated planar holograms on multimode interference
couplers,” Opt. Lett., vol. 34, no. 4, pp. 512–514, 2009.
[25] A. Sure, T. Dillon, J. Murakowski, C. Lin, D. Pustai, and D. W. Prather,
“Fabrication and characterization of three-dimensional silicon tapers,”
Opt. Exp., vol. 11, no. 26, pp. 3555–3561, 2003.
2
Shuo-Yen Tseng received the B.S. degree in electrical engineering from National Taiwan University, Taipei, Taiwan, in 1999 and the M.S. and Ph.D. degrees in electrical engineering from the University of Maryland, College Park,
USA, in 2002 and 2006, respectively.
In 2007, he joined Georgia Institute of Technology as a post doctoral fellow in
Prof. Bernard Kippelen’s Research Group where he studied organic photonics.
In August 2008, he joined the faculty at the National Cheng Kung University,
Tainan, Taiwan, as an Assistant Professor in the Department of Electro-Optical
Engineering. His research interests include optical communications, numerical
simulation, nanotechnology and integrated photonics.
Dr. Tseng is a member of the Optical Society of America (OSA).
Ming-Chan Wu received the B.S. degree in physics from Soochow University,
Taipei, Taiwan, in 2003 and the M.S. degree in optics and photonics from the
National Central University, Jhongli, Taiwan, in 2007.
He is currently a Research Assistant at the Department of Electro-Optical
Engineering, National Cheng Kung University, Tainan, Taiwan.