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Author

Hiroaki Sanjoh

Bio: Hiroaki Sanjoh is an academic researcher from Nippon Telegraph and Telephone. The author has contributed to research in topics: Distributed feedback laser & Laser. The author has an hindex of 19, co-authored 78 publications receiving 1219 citations.


Papers
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Journal ArticleDOI
TL;DR: In this paper, a 1.3-μm distributed-feedback laser with a ridge waveguide structure was used to achieve 50-Gb/s clear eye openings with a back-to-back configuration, and achieved a mean output power of over 5.0 dBm, and a dynamic extinction ratio of 4.5 dB.
Abstract: We demonstrate 50-Gb/s direct modulation by using 1.3-μm distributed-feedback lasers with a ridge waveguide structure. We employed InGaAlAs material for a multiple-quantum well to obtain a low damping factor K, and fabricated a ridge waveguide structure buried in benzocyclobutene to realize a structure with a low parasitic capacitance. In addition, to obtain high maximum frequency relaxation oscillations fr, we designed the cavity length L), and achieved a 3-dB-down frequency bandwidth of 34 GHz. We realized 50-Gb/s clear eye openings with a back-to-back configuration, and achieved a mean output power of over 5.0 dBm, and a dynamic extinction ratio of 4.5 dB. We measured the 50-Gb/s transmission characteristics, and obtained clear eye openings for transmissions over 20-, 40-, and 60-km single-mode fibers (SMF). We also measured the bit-error-rate performance, and obtained an error-free operation and a power penalty of less than 0.5 dB after a 10-km SMF transmission.

105 citations

Proceedings ArticleDOI
17 Mar 2002
TL;DR: In this paper, a novel optical orthogonal frequency division multiplexing (OFDM) technique was proposed, which can overcome the spectral efficiency limitation of the conventional WDM system up to 1 bit/s/Hz in principle.
Abstract: Summary form only given. We have proposed a novel optical orthogonal frequency division multiplexing technique that can overcome the spectral efficiency limitation of the conventional WDM system. This scheme permits substantial overlapping of the spectrum and can achieve the spectral efficiency up to 1 bit/s/Hz in principle. For demultiplexing, we used a newly developed optical discrete Fourier transformer (DFT) instead of electrical digital processing, which is impossible to apply in the optical frequency range. The optical DFT was realized by using a set of delay lines, a phase shifter and a coupler in the frequency domain and bit synchronization and an optical gate in the time domain. In experimental demonstration of this scheme, error-free operation was obtained with a 0.8 bit/s/Hz of spectral efficiency.

94 citations

Journal ArticleDOI
TL;DR: The largest-scale arrayed-waveguide-grating multiplexer ever has been fabricated on an InP substrate as mentioned in this paper, which has 64 input/output ports with 0.4 nm channel spacing and a chip size as small as 3.6/spl times/7.0 mm.
Abstract: The largest-scale arrayed-waveguide-grating multiplexer ever has been fabricated on an InP substrate. The device has 64 input/ output ports with 0.4 nm (50 GHz) channel spacing and a chip size as small as 3.6/spl times/7.0 mm. The crosstalk is <-20 dB for neighbouring and all other channels.

92 citations

Proceedings ArticleDOI
20 Mar 2016
TL;DR: Using a lumped-electrode EADFB laser with a modulation bandwidth of ~59 GHz, this work demonstrated single-wavelength single-polarization direct-detection 4-PAM transmission with the record net data rate of 200 Gbit/s.
Abstract: Using a lumped-electrode EADFB laser with a modulation bandwidth of ∼59 GHz, we demonstrated single-wavelength single-polarization direct-detection 4-PAM transmission with the record net data rate of 200 Gbit/s.

74 citations


Cited by
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Journal ArticleDOI
TL;DR: An optical fast Fourier transform scheme is demonstrated that provides the necessary computing power to encode lower-bitrate tributaries into 10.8 and 26.0 Tbit s-1 line-rate orthogonal frequency division multiplexing (OFDM) data streams and to decode them from fibre-transmitted OFDM data streams.
Abstract: Optical transmission systems with terabit per second (Tbit s-1) single-channel line rates no longer seem to be too far-fetched. New services such as cloud computing, three-dimensional high-definition television and virtual-reality applications require unprecedented optical channel bandwidths. These high-capacity optical channels, however, are fed from lower-bitrate signals. The question then is whether the lower-bitrate tributary information can viably, energy-efficiently and effortlessly be encoded to and extracted from terabit per second data streams. We demonstrate an optical fast Fourier transform scheme that provides the necessary computing power to encode lower-bitrate tributaries into 10.8 and 26.0 Tbit s-1 line-rate orthogonal frequency division multiplexing (OFDM) data streams and to decode them from fibre-transmitted OFDM data streams. Experiments show the feasibility and ease of handling terabit per second data with low energy consumption. To the best of our knowledge, this is the largest line rate ever encoded onto a single light source.

544 citations

Journal ArticleDOI
TL;DR: The paper explains the concept of generic photonic integration technology using the technology developed by the COBRA research institute of TU Eindhoven as an example, and it describes the current status and prospects of generic InP-based integration technology.
Abstract: Photonic integrated circuits (PICs) are considered as the way to make photonic systems or subsystems cheap and ubiquitous. PICs still are several orders of magnitude more expensive than their microelectronic counterparts, which has restricted their application to a few niche markets. Recently, a novel approach in photonic integration is emerging which will reduce the R&D and prototyping costs and the throughput time of PICs by more than an order of magnitude. It will bring the application of PICs that integrate complex and advanced photonic functionality on a single chip within reach for a large number of small and larger companies and initiate a breakthrough in the application of Photonic ICs. The paper explains the concept of generic photonic integration technology using the technology developed by the COBRA research institute of TU Eindhoven as an example, and it describes the current status and prospects of generic InP-based integration technology.

512 citations

Journal ArticleDOI
TL;DR: Incorporating wavelength-division multiplexing (WDM) in a PON allows one to support much higher bandwidth compared to the standard PON, which operates in the traditional copper-based networks.
Abstract: Feature Issue on Optical Access Networks (OAN) The passive optical network (PON) is an optical fiber based network architecture, which can provide much higher bandwidth in the access network compared to traditional copper-based networks. Incorporating wavelength-division multiplexing (WDM) in a PON allows one to support much higher bandwidth compared to the standard PON, which operates in the "single-wavelength mode" where one wavelength is used for upstream transmission and a separate one is used for downstream transmission. We present a comprehensive review of various aspects of WDM-PONs proposed in the literature. This includes enabling device technologies for WDM-PONs and network architectures, as well as the corresponding protocols and services that may be deployed on a WDM-PON. The WDM-PON will become a revolutionary and scalable broadband access technology that will provide high bandwidth to end users.

507 citations

Journal ArticleDOI
TL;DR: In this article, the authors review the recent progress of information theory in optical communications and describe the current experimental results and associated advances in various individual technologies which increase the information capacity, and confirm the widely held belief that the reported capacities are approaching the fundamental limits imposed by signal-to-noise ratio and the distributed nonlinearity of conventional optical fibres, resulting in the reduction in the growth rate of communication capacity.
Abstract: We review the recent progress of information theory in optical communications, and describe the current experimental results and associated advances in various individual technologies which increase the information capacity. We confirm the widely held belief that the reported capacities are approaching the fundamental limits imposed by signal-to-noise ratio and the distributed non-linearity of conventional optical fibres, resulting in the reduction in the growth rate of communication capacity. We also discuss the techniques which are promising to increase and/or approach the information capacity limit.

493 citations

Journal ArticleDOI
TL;DR: This study highlights systems challenges and performance issues which need to be addressed in order to incorporate wavelength conversion effectively in wavelength-convertible networks.
Abstract: Wavelength conversion has been proposed for use in wavelength-division multiplexed networks to improve efficiency. This study highlights systems challenges and performance issues which need to be addressed in order to incorporate wavelength conversion effectively. A review/survey of the enabling technologies, design methods, and analytical models used in wavelength-convertible networks is provided.

441 citations