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Takashi ONO Masahito TOMIZAWA Tomoyoshi KATAOKA Akihiko MATSUURA Yoshiaki KISAKA Yutaka MIYAMOTO Kazushige YONENAGA Shoichiro KUWAHARA Yasuhiko TADA Hiromu TOBA
This paper describes the design concept and realized functions of the first Optical Transport Network (OTN) based 43 Gbit/s line terminal. The system requirements of new generation networks are provided, and the functions needed in this line terminal are obtained from the requirements. The line terminal deploys Time Division Multiplexing (TDM) to handle client signals, and provides transparent high quality multiple services such as SONET/SDH and Gigabit Ethernet. The configuration and features of the actually fabricated system are described.
Hiroto KAWAKAMI Shoichiro KUWAHARA Yoshiaki KISAKA
We show that imperfection in an IQ-modulator degrades the accuracy of the auto bias control (ABC) circuit connected to the modulator's complementary port. Theoretical analyses show that the IQ-modulator constructed by a nested Mach-Zehnder modulator with a low extinction ratio can distort a constellation of modulated light observed at the complementary port. We propose an auto calibration technique for the ABC circuit that can effectively suppress this degradation. Experimental results using 32-Gbaud, 16-QAM signals showed the measured Q-factor improved by 0.5dB with our proposed technique.
Kenji SATO Shoichiro KUWAHARA Yutaka MIYAMOTO Koichi MURATA Hiroshi MIYAZAWA
Phase-inversion between neighboring pulses appearing in carrier-suppressed return-to-zero pulses is effective in reducing the signal distortion due to chromatic dispersion and nonlinear effects. A generation method of the anti-phase pulses at 40 GHz is demonstrated by using semiconductor mode-locked lasers integrated with chirped gratings. Operation principle and pulse characteristics are described. Suppression of pulse distortion due to fiber dispersion is confirmed for generated anti-phase pulses. Repeaterless 150-km dispersion-shifted-fiber L-band transmission at 42.7 Gbit/s is demonstrated by using the pulse source.
Fukutaro HAMAOKA Takeo SASAI Kohei SAITO Takayuki KOBAYASHI Asuka MATSUSHITA Masanori NAKAMURA Hiroki TANIGUCHI Shoichiro KUWAHARA Hiroki KAWAHARA Takeshi SEKI Josuke OZAKI Yoshihiro OGISO Hideki MAEDA Yoshiaki KISAKA Masahito TOMIZAWA
We demonstrated 1-Tb/s-class transmissions of field-deployed large-core low-loss fiber links, which is compliant with ITU-T G.654.E, using our newly developed real-time transponder consisting of a state-of-the-art 16-nm complementary metal-oxide-semiconductor (CMOS) based digital signal processing application-specific integrated circuit (DSP-ASIC) and an indium phosphide (InP) based high-bandwidth coherent driver modulator (HB-CDM). In this field experiment, we have achieved record transmission distances of 1122km for net data-rate 1-Tb/s transmission with dual polarization-division multiplexed (PDM) 32 quadrature amplitude modulation (QAM) signals, and of 336.6 km for net data-rate 1.2-Tb/s transmission with dual PDM-64QAM signals. This is the first demonstration of applying hybrid erbium-doped fiber amplifier (EDFA) and backward-distributed Raman amplifier were applied to terrestrial G.654.E fiber links. We also confirmed the stability of signal performance over field fiber transmission in wavelength division multiplexed (WDM) condition. The Q-factor fluctuations respectively were only less than or equal to 0.052dB and 0.07dB for PDM-32QAM and PDM-64QAM signals within continuous measurements for 60 minutes.
Shoichiro KUWAHARA Kazushige YONENAGA Yutaka MIYAMOTO Yoshiaki KISAKA Kenji SATO Akira HIRANO Takashi ONO Akihiko MATSUURA Masahito TOMIZAWA Tomoyoshi KATAOKA Yasuhiko TADA Hiromu TOBA Kazuo HAGIMOTO Nobuhiro HIRAYAMA Hirotaka ASAI
The first results of a field trial held in November 2000, of 1 Tbit/s (25 43 Gbit/s) unidirectional Wavelength Division Multiplexing (WDM) transmission, are presented. The field trial used a 43 Gbit/s/channel Optical Transport Network (OTN) interface prototype and standard Single Mode Fibers (SMFs) installed in the Nara area network of NTT West Corporation. The features of this field trial include the accommodation of multiple services such as GbE, STM-16 and OC-48. Error free operation of 25 channels with 100 GHz spacing over a 91 km standard SMF with Forward Error Correction (FEC) is verified for STM-16. A DV stream over IP over Ethernet as a tributary channel was also successfully transmitted.