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Full list of publication from our group can be found here.
Selected publications
T. Hirooka, M. Okazaki, T. Hirano, P. Guan, M. Nakazawa, and S. Nakamura,
“All-optical demultiplexing of 640-Gb/s OTDM-DPSK signal using a semiconductor SMZ switch,”
IEEE Photon. Technol. Lett., vol. 21, no. 20, pp. 1574-1576, October (2009).
The all-optical demultiplexing of a 640-Gb/s single- polarization optical
time-division-multiplexing signal is successfully demonstrated by using a symmetric
Mach-Zehnder switch incorporating semiconductor optical amplifiers. An ultrafast
switching gate as narrow as 1.4 ps is realized by using a low-jitter, subpicosecond pulse
train as a control pulse, which facilitates low-penalty demultiplexing.
Go to IEEE Xplore to download PDF
K. Kasai, T. Omiya, P. Guan, M. Yoshida, T. Hirooka, and M. Nakazawa,
“Single-channel 400-Gb/s OTDM-32 RZ/QAM coherent transmission over 225 km using an
optical phase-locked loop technique,” IEEE Photon. Technol. Lett., vol. 22, no. 8,
pp. 562-564, April (2010).
A single-channel 400-Gb/s transmission with a polarization-multiplexed , 10-Gsymbol/s,
four-optical time-division multiplexed (OTDM) 32 return-to-zero/quadrature amplitude
modulation (RZ/QAM) scheme is demonstrated for the first time. By using an optical
phase-locked loop technique and a clock recovery circuit, we have successfully obtained
a very stable pulsed-local oscillator whose phase was locked to the transmitter, and
achieved precise demultiplexing and demodulation simultaneously. As a result, 400-Gb/s
data were transmitted over 225 km with a bit-error-rate performance below the forward-error
correction limit. Furthermore, we also realized a 320-Gb/s to 450-km transmission with an
OTDM 16 RZ/QAM scheme.
Go to IEEE Xplore to download PDF
T. Hirano, P. Guan, T. Hirooka, and M. Nakazawa, “640-Gb/s/channel single-polarization
DPSK transmission over 525 km with ultrafast time-domain optical Fourier transformation,”
IEEE Photon. Technol. Lett., vol. 22, no. 14, pp. 1042-1044, July (2010).
A single-channel 640-Gb/s differential phase-shift-keying transmission over 525 km
was successfully demonstrated in a single polarization. A new ultrafast time-domain
optical Fourier transformation (OFT) circuit was developed, in which the strong chirp
required for the OFT of a subpicosecond optical pulse was realized with a phase modulator
operated in a round-trip configuration. By applying this technique to a 640-Gb/s transmission,
the tolerance to higher order polarization-mode dispersion was greatly improved and error-free
transmission was achieved.
Go to IEEE Xplore to download PDF
P. Guan, H. C. H. Mulvad, Y. Tomiyama, T. Hirano, T. Hirooka, and M. Nakazawa,
“1.28 Tbit/s/channel Single-polarization DQPSK Transmission over 525 km Using Ultrahigh-speed
Time-domain Optical Fourier Transformation,” ECOC2010, We.6.C.3.
A single-channel 1.28 Tbit/s transmission over 525 km is demonstrated for the first time
with a single-polarization DQPSK signal. Ultrafast time-domain optical Fourier transformation
is successfully applied to DQPSK signals and results in improved performance and increased
system margin.
H. C. H. Mulvad, P. Guan, K. Kasai, T. Hirooka, and M. Nakazawa,
“High-Resolution 640 Gbit/s Clock Recovery using Time-Domain Optical Fourier Transformation and
Narrowband Optical Filter,” ECOC2010, Mo.1.A.6
We demonstrate pre-scaled 40 GHz clock recovery from 640 Gbit/s optical time-division-multiplexed
data using LiNbO3 modulators, based on time-domain optical Fourier transformation and optical
filtering. The clock recovery is used in a 640 Gbit/s error-free transmission over 300 km.
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