Optoelectronic Laboratory
Focus Areas
• Photonic Signal Processing
• Planar waveguide devices
Research Team:
Professors K. T. Chan, Chester Shu, Hon Tsang, Chinlon Lin
+ 4 research staff + 15 graduate students
Center for Advanced Research in Photonics
Department of Electronic Engineering, The Chinese University of Hong Kong
Examples of Research Output
•
All-optical signal processing
– Photonic ADC
– Polarization diversity loop for polarization insensitive operation
– Wavelength conversion using
•
•
•
•
– Data Modulation Format Conversion (RZ to NRZ and NRZ to RZ)
– OTDM demultiplexing
Waveguides
– Polarization dependent frequency and polarization dependent loss compensation via
•
•
FIB trimming
Magnetostrictive layer deposited on waveguide
– InGaAsP Waveguide Fabry-Perot filter (high speed tuneable via current injection)
– Nonlinear Applications of SOI waveguides : Raman Amplification
– Material properties (measure dispersion, Kerr effect & TPA in SOI waveguides)
Ultrafast optics and nonlinear optics
– Spectral measurement in time domain using dispersion
– Two photon autocorrelation using InGaAsP and Si waveguides
– Terahertz pulse generation and detection using ion implanted GaAs
400
TPA signal (a.u.)
•
FWM in SOA
Birefringence Switching
Dual wavelength injection locking
360
320
280
240
200
-8
-6
-4
-2
0
2
4
Delay time (ps)
T.K.Liang and H.K.Tsang, APPL PHYS
LETT 81 (7): 1323 AUG 2002
Center for Advanced Research in Photonics
Department of Electronic Engineering, The Chinese University of Hong Kong
6
8
Photonic ADC
Lee KL, Shu C: “Switching-wavelength pulse source constructed from a dispersion-managed SOA fiber
ring laser” IEEE PHOTONICS TECHNOLOGY LETTERS 15 (4): 513-515 APR 2003
• Sampling in optical domain and quantization in electronic domain
Microwave signal
quantization
Optical Source
Sampling
Transducer
: electrical signal
: optical signal
Optical Source
Digital
signal
processor
Optical
Demux
quantization
: Time and wavelength-interleaved pulses
/ Fiber laser
Center for Advanced Research in Photonics
Department of Electronic Engineering, The Chinese University of Hong Kong
10 Gigasample/s Photonic ADC using 10-wavelength sampling pulses
•10 channel output from
l1 = 1560.14 to
l10 = 1569.47 nm
•Channel spacing: 1.03 nm
•Suppression of non-lasing
mode > 20 dB
•Overall repetition rate: 10 GHz
Individual l operated at 1 GHz
•Pulse width: 21-26 ps
•Timing jitter < 0.2 ps
Center for Advanced Research in Photonics
Department of Electronic Engineering, The Chinese University of Hong Kong
All-optical wavelength conversion
PC4
C1
PC1
OC
1
2
3
PC2
ls
Signal (S)
lP1
lC
B
A
PC5
C
D
WDM
Demultiplexer
Pump 1 (P1)
SOA
PBS
Converted
Signal
PC3
Isolator
Pump 2 (P2)
lP2
-5.0
Input signal
Converted signal
-6.0
log(BER)
-7.0
-8.0
-9.0
0.9 dB
-10.0
10 ps / div
10 ps / div
Back-to-back
-11.0
Converted
-12.0
40 Gb/s wavelength conversion
-36
-34
-32
-30
-28
-26
Received optical power (dBm)
M.W.K. Mak, H.K. Tsang and K.Chan: “Widely tunable polarization-independent all-optical wavelength
converter using a semiconductor optical amplifier,” IEEE Phot. Tech. Lett., vol.12, 525-527 (2000)
Center for Advanced Research in Photonics
Department of Electronic Engineering, The Chinese University of Hong Kong
Wavelength conversion: BOP FWM without external optical pump
l
Pump 1
l
SOA
l
Output
Signal
Pump 2
l
K. K. Chow, C. Shu, M. W. K. Mak and H. K. Tsang, “Widely tunable wavelength
converter using a double-ring fiber laser with a semiconductor optical amplifier,” IEEE
Photonics Technology Letters, vol. 14, pp. 1445-1447, October 2002.
Center for Advanced Research in Photonics
Department of Electronic Engineering, The Chinese University of Hong Kong
Tunable 40Gbit/s optical source
C
3
1
HDF
Optical
Coupler
OC
PC1
FPLD
SOA
FFP
PC2
RF Synthesizer
Dispersive frequency
multiplication
Isolator
Mode-locked SOA
fiber-ring laser
Output
Pulsewidth (ps)
2
20
18
16
14
12
10
8
6
4
2
0
1540
1545
1550
1555
1560
Wavelength (nm)
Mark W.K.Mak and H.K.Tsang: “Dispersive Frequency Multiplication for Wavelength-Tunable High
Repetition Rate Pulse-Train Generation,”Optical Fiber Communications 2001 (Anaheim), 2001.
Center for Advanced Research in Photonics
Department of Electronic Engineering, The Chinese University of Hong Kong
1565
1570
Optical CDMA
Wang X, Lee KL, Shu C, Chan KT: “Multiwavelength self-seeded Fabry-Perot laser with subharmonic pulsegating for two-dimensional fiber optic-CDMA,” IEEE PHOTONICS TECHNOLOGY LETTERS 13 (12): 13611363 DEC 2001
Center for Advanced Research in Photonics
Department of Electronic Engineering, The Chinese University of Hong Kong
High speed tunable filter
• Tunable waveguide filter
Input waveguide
FP cavity made by
anisotropic etching
(CAIBE)
Output waveguide
Cladding layer
E
Guiding region
E'
M
Anti-reflection coating
M
High reflectivity coating
Peak Transmission Shift (nm)
5
4
3
2
1
0
Substrate
0
10
20
30
40
Current Injection (mA)
H.K. Tsang et al. “ Etched Cavity InGaAsP/InP Waveguide Fabry-Perot Filter Tunable by Current
Injection,” IEEE J. Lightwave Tech, vol.17, p.1890-1895 (1999)
Center for Advanced Research in Photonics
Department of Electronic Engineering, The Chinese University of Hong Kong
50
60
Polarization compensation by magnetostriction
Magnetostriction: anisotropic strain induced by magnetic field
Saturation Magnetostriction constant (l)

l

=fractional change in length
Rib oxide w ith annealing
Whole w aveguide covered by TiO2
Whole w aveguide covered by CoFe
1.5
DGD (ps )
y
1.0
x
0.5
External Magnetic field
direction
0.0
No B-field
B-field applied
Ferromagnetic film
6
PDL (dB)
4
2
0
No B-f ield
B-f ield applied
Thermal oxide
Silicon
Buried Oxide
Silicon
P.S. Chan, H.K. Tsang, “Magnetostrictive Polarization Compensation on SOI Rib Waveguide”, 8th
OptoElectronics and Communications Conference, Shanghai, China, Oct 2003.
Center for Advanced Research in Photonics
Department of Electronic Engineering, The Chinese University of Hong Kong
Focused Ion Beam Etching for mode conversion and PDF adjustment
Side view of trimmed
portion of rib.
Gallium
Ion
Top view of trimmed rib SOI
waveguide by 45 degrees, 10m
Output
power (dBm)
TE
Percentage of Mode Conversion
TM
TE
TM
-6
100%
-8
80%
60%
-10
40%
-12
20%
WITHOUT
compensation
Compensated
by 10um FIB
-14
trimming
0%
0
50
100
Trim Length (m)
150
-16
1550.02
1550.06
1550.10
1550.14
Wavelength (nm)
P.S. Chan, H.K. Tsang, C. Shu, “Mode Conversion and Birefringence Adjustment via Focused
Ion Beam Etching for Slanted rib Waveguide walls”, to appear in Optics Lett. Nov. 2003.
Center for Advanced Research in Photonics
Department of Electronic Engineering, The Chinese University of Hong Kong
1550.18
Silicon oxynitride switch
trench for liquid crystal material for switching
A Zhang and KT Chan “Characterization of the optical loss of an integrated silicon oxynitride
optical switch structure,” Appl. Phys. Lett., Vol. 83, No. 13, 29 September 2003
Center for Advanced Research in Photonics
Department of Electronic Engineering, The Chinese University of Hong Kong
New topics of current interest
• Raman gain in silicon waveguides (HK Tsang)
SiO2
p+
Si
n+
DFB
Laser
Coupler
waveguide
Si (substrate)
Monochrometer
Power
Meter
1683 1684 1685 1686
Stokes l (nm)
• Quantum encryption using multiphoton entanglement generated from
spontaneous parametric down conversion (KT Chan)
• Photonic Crystal Fibers for signal processing and sensors (CT Shu)
Center for Advanced Research in Photonics
Department of Electronic Engineering, The Chinese University of Hong Kong
Future Directions in planar waveguides & nanophotonics
• Possible future directions:
– Miniaturization of planar waveguide components using silicon wires
• Requires considerable investment to improve dry etching capability
(HKUST equipment is inadequate for etching submicron waveguides)
• Work needed on improving coupling loss and polarization dependence
– Periodic structures (thin film photonic crystal)?
From Richard M. De La Rue
“Photonic Crystal and Photonic
Wire Devices and Technology”
ECOC 2003
“The technological problems involved
in fabrication with sufficient precision
and acceptable propagation losses
continue to present a major challenge
for device engineers and physicists.”
“… the likely impact of photonic crystal and photonic wire…is considerable. Within a small number of years, we are likely to witness
moderately high volume production of devices which will incorporate the thinking that has been developed over a period of sixteen or more
years”
Center for Advanced Research in Photonics
Department of Electronic Engineering, The Chinese University of Hong Kong
Photonic Packaging Laboratory
• A 3-year project with $12.334 million total funding from ITF and sponsors
Project period: June 2001- May 2004
Funded by:
W.T. and H. S. Chan
Christian Service
Foundation Limited
Major Equipment:
•
•
•
•
•
•
•
Optical Thin Film Coating System
Laser Welder
Automated Alignment System
Polishing System
Auto-Stepback Wedge Bonder
Precision Die Bonder
Wafer scriber
Center for Advanced Research in Photonics
Department of Electronic Engineering, The Chinese University of Hong Kong
Photonic Packaging Laboratory
Mission:
To help build a photonic packaging infrastructure in Hong Kong by:
1. support R&D in industry and academia;
2. technical training;
3. facilitate technology transfer to industry.
Technical Team:
13 engineering faculty staff from IE, EE,
and ACAE departments,
plus 3 full-time technical staff
(Dr. Ming Li, April PS Chung, MT Yeung)
PI : Hon Tsang, Chester Shu
Coordinator: Frank Tong
Center for Advanced Research in Photonics
Department of Electronic Engineering, The Chinese University of Hong Kong
Milestone 1 – Fiber attach and basic optical coatings
Completed 31/7/2002
Packaged Components:
Lasers, Photodetectors
Butterfly FP/DFB laser module
• AR and HR coated FP Laser
Pigtailed TO-Can
photodetector
1 Gb/s
Center for Advanced Research in Photonics
Department of Electronic Engineering, The Chinese University of Hong Kong
Milestone 2: High Specification Coatings
Completed 28/2/2003
• AR coatings (<0.05% reflectivity) on Si and III-V semiconductors
HR overlay coatings to enhance reflection and reduce PDL from gold mirrors
material
t (nm)
8. Ta2O5
192
7. SiO2
310
6. Ta2O5
192.89
5. SiO2
308.7
4. Ta2O5
193.19
3. SiO2
308.04
2. Ta2O5
193.32
1. SiO2
278.61
0. Au
50
Si sub.
Center for Advanced Research in Photonics
Department of Electronic Engineering, The Chinese University of Hong Kong
Milestone 4: Fiber array attachment and MEMS packaging
due 30/11/2003
Collimating fiber
Bonding pads
Supporting Si
Si U-grove / V-grove
Input 1
Input 2
Si optical
bench
Glass
MEMS
Output 1 Output 2
Center for Advanced Research in Photonics
Department of Electronic Engineering, The Chinese University of Hong Kong
Milestone 5: Multi-component packaging
due 31/5/2004
waveguide
Side
alignment
pedestals
•
•
•
Laser
chip
Side alignment
pedestal
Laser die
solder
Plated
Ni/Au
Ti/Au/Ti/SiO2
Substrate
Development of novel self-aligned flip-chip technology for hybrid integration of
laser arrays to planar waveguides
Collaboration with Institute of Semiconductors, Chinese Academy of Sciences
in Beijing on fabrication of compatible FP laser array
Collaboration with Shipley on photoresist suitable for 3D topography (needed
for patterning metal at bottom of trench
Center for Advanced Research in Photonics
Department of Electronic Engineering, The Chinese University of Hong Kong