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1.
Opt Express ; 27(8): 11227-11235, 2019 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-31052969

RESUMO

A PAM4-OCDM system with optical multi-/demultiplexing and electrical pre-/post-processing is proposed for short-reach applications. We experimentally demonstrate, for the first time, a power-efficient 4 OC x 10 GSymbol/s PAM4-OCDM system. The four PSK-OCs are simultaneously generated using a single light source and a passive multiport optical encoder and received by a single optical decoder and cascaded DSP. The effectiveness of the electrical-domain amplitude level pre-tuning and post-equalizer are demonstrated, considering different values of shot and beat noises.

2.
Opt Express ; 26(18): 24098-24113, 2018 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-30184902

RESUMO

One of the key features of the forthcoming fifth-generation (5G) communications is the deployment of massive multiple-input-multiple-output (MIMO) antennas to support ultra-high mobile traffic density. This scenario will pose a serious challenge on the capacity of mobile fronthaul in the centralized/cloud radio access network (C-RAN) since the required fronthaul bandwidth would linearly increase with number of antennas if conventional fronthaul interfaces (e.g., CPRI) are used. In this paper, we propose an adaptive space-time compression technique to significantly improve bandwidth efficiency of fronthaul. The technique incorporates an adaptive spatial filter to track the signal subspace and reduce the number of spatial channels, followed by adaptive quantizers to compress bandwidth of each channel in time domain. Enabled by the technique, the required fronthaul bandwidth becomes only dependent on the number of users, which is no longer proportional to the number of antennas. Moreover, compared with traditional fronthaul compression schemes in only the time domain, the flexibility of the compressor increases, and joint space-time optimization becomes feasible. On the other hand, optical fronthaul bandwidth is usually limited by cost-effective optical and electronic components. Moreover, increased reach would limit the bandwidth of IM-DD-based fronthaul (due to chromatic dispersion) as well as the received optical power. We experimentally investigate the combined optimization of a proposed space-time compressor with an optical fronthaul link. Experimental results of uplink 256-antenna fronthaul (259.5-Gb/s CPRI-equivalent rate) show that 32 users with 20MHz (30.72MSa/s) OFDM signal with lower-than-1% EVM are supported by 10GBd PAM4 optical interface.

3.
Opt Express ; 23(20): 25747-61, 2015 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-26480089

RESUMO

This paper deals with massive number of optical code (OC) label generation and recognition for scalable optical packet switching (OPS) networks. In order to expand the system scalability of code label processing, we develop a record port count 128 x 128 optical encoder/decoder (E/D) and propose a novel three-dimensional (3-D) optical label combining code label with wavelength and polarization. In the experiment, we conduct a proof-of-concept demonstration of 4-code x 2-wavelength x 2-polarization and validate that the 3-D labeling scheme can consequently increase the available number of code label up to more than 1,000 labels. Real-time labeling performance using a field programmable gate array (FPGA)-based processor and crosstalk influence at an optical switch are also experimentally evaluated.

4.
Opt Express ; 22(23): 28719-30, 2014 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-25402112

RESUMO

Photonic analog-to-digital conversion and optical quantization are demonstrated, based on the spectral shifts of orthogonal frequency division multiplexing subcarriers and a frequency-packed arrayed waveguide grating. The system is extremely low-energy consuming since the spectral shifts are small and generated by cross-phase modulation, using a linear-slope high-speed and low-jitter pulse train generated by a mode locked laser diode. The feasibility of a 2, 3 and 4-bit optical quantization scheme is demonstrated.


Assuntos
Fótons , Processamento de Sinais Assistido por Computador , Análise Espectral , Conversão Análogo-Digital , Simulação por Computador , Dinâmica não Linear , Análise Numérica Assistida por Computador , Fibras Ópticas
5.
Opt Express ; 22(10): 12060-9, 2014 May 19.
Artigo em Inglês | MEDLINE | ID: mdl-24921325

RESUMO

A novel hybrid all-optical mode-division multiplexing and code division multiplexing architecture for flexible and scalable access networks is presented. We successfully demonstrate, for the first time, an asynchronous on-off keying modulation, 2 mode x 4 code x 10 Gbps transmission over 42-km link, using a set of single-mode and two-mode fibers, without dispersion compensation. The four phase-shift keyed optical codes are generated at a single wavelength, by a multiport encoder/decoder, and we use an optical mode multiplexer/demultiplexer in the remote node and at the central office. We also experimentally evaluate the mode crosstalk tolerance considering different access span distances for the LP(01) and LP(11) modes.

6.
Opt Lett ; 39(2): 355-8, 2014 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-24562145

RESUMO

We propose for the first time (to the best of our knowledge) and demonstrate a tunable multiple optical code (OC) converter for flexible networks that allows dynamic code (bandwidth) allocation in a way similar to a tunable laser. With respect to other OC converters, this scheme can convert both specific and multiple OCs by changing only the amplifier gain. The proposed scheme uses cross-phase modulation (XPM) and two linear-slope control pulse streams generated by fiber Bragg gratings (FBGs) in the C-band. The OC converter can be used to avoid collisions in optical packet switching networks, and we analyze the corresponding packet loss probability performance.

7.
Opt Express ; 21(10): 12282-301, 2013 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-23736447

RESUMO

This paper proposes a novel bandwidth-elastic and energy-efficient passive optical network (PON) based on the coherent interleaved frequency division multiple access (IFDMA) scheme. We experimentally demonstrate the coherent IFDMA-PON uplink transmission up-to 30 Gbps over a 30 km standard single-mode fiber with 2 × optical network units (ONUs). A low-complexity digital carrier synchronization technique enables multiple access of the ONUs on the basis of 78.1 MHz narrow band orthogonal subcarriers without any guard-bands.


Assuntos
Redes de Comunicação de Computadores/instrumentação , Tecnologia de Fibra Óptica/instrumentação , Armazenamento e Recuperação da Informação/métodos , Dispositivos Ópticos , Processamento de Sinais Assistido por Computador/instrumentação , Transferência de Energia , Desenho de Equipamento , Análise de Falha de Equipamento
8.
Opt Express ; 20(24): 27311-21, 2012 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-23187586

RESUMO

All-optical technique for modulation format conversion from 4 channels non-return-to-zero on-off-keying (OOK) to return-to-zero 16 quadrature amplitude modulation (16QAM) employing nonlinear optical loop mirror with 1:2 coupler configuration is proposed and experimentally demonstrated at 10Gs/s. The experimentally converted 16QAM signal was distorted in its phase by cross-phase modulation induced amplitude-to-phase noise conversion. The effect of amplified spontaneous emission noise in the amplified OOK signals to the converted 16QAM's phase was theoretically discussed.


Assuntos
Lasers , Fibras Ópticas , Refratometria/instrumentação , Processamento de Sinais Assistido por Computador/instrumentação , Telecomunicações/instrumentação , Transdutores , Desenho Assistido por Computador , Desenho de Equipamento , Semicondutores
9.
Opt Express ; 20(9): 10320-9, 2012 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-22535121

RESUMO

We propose a novel receiver configuration using an extreme narrow band-optical band pass filter (ENB-OBPF) to reduce the multiple access interference (MAI) and beat noises in an optical code division multiplexing (OCDM) transmission. We numerically and experimentally demonstrate an enhancement of the code detectability, that allows us to increase the number of users in a passive optical network (PON) from 4 to 8 without any forward error correction (FEC).


Assuntos
Algoritmos , Artefatos , Filtração/instrumentação , Dispositivos Ópticos , Processamento de Sinais Assistido por Computador/instrumentação , Telecomunicações/instrumentação , Desenho de Equipamento , Análise de Falha de Equipamento
10.
Opt Express ; 20(28): 29395-403, 2012 Dec 31.
Artigo em Inglês | MEDLINE | ID: mdl-23388767

RESUMO

Multi-input multi-output (MIMO) transmission of two millimeter-wave radio signals seamlessly converted from polarization-division-multiplexed quadrature-phase-shift-keying optical signals is successfully demonstrated, where a radio access unit basically consisting of only optical-to-electrical converters and a radio receiver performs total signal equalization of both the optical and the radio paths and demodulation with digital signal processing (DSP). Orthogonally polarized optical components that are directly converted to two-channel radio components can be demultiplexed and demodulated with high-speed DSP as in optical digital coherent detection. 20-Gbaud optical and radio seamless MIMO transmission provides a total capacity of 74.4 Gb/s with a forward error correction overhead of 7%.

11.
Opt Express ; 19(26): B56-63, 2011 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-22274070

RESUMO

The generation of a 40-Gb/s 16-QAM radio-over-fiber (RoF) signal and its demodulation of the wireless signal transmitted over free space of 30 mm in W-band (75-110 GHz) is demonstrated. The 16-QAM signal is generated by a coherent polarization synthesis method using a dual-polarization QPSK modulator. A combination of the simple RoF generation and the versatile digital receiver technique is suitable for the proposed coherent optical/wireless seamless network.

12.
Opt Express ; 19(26): B965-70, 2011 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-22274127

RESUMO

We have developed a new 8-chip, 320 Gchip/s encoder/decoder with eight input/output ports, that can be used in 40-Gb/s PON networks. The device has been to multiplex four asynchronous 40 Gb/s users, using DPSK modulation. The transmission over 50 km has been successfully demonstrated for the first time.

13.
Opt Express ; 19(27): 26872-82, 2011 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-22274270

RESUMO

Optical flow switching (OFS) has been proposed as a simple and cost-effective transport technology for users with large transactions (>1 second). In previous studies, a fast wavelength reservation method was deployed for flow transmission in OFS-based networks. However, reserving a single wavelength for users with small transactions encounters a very common problem: inefficient wavelength utilization. In this paper, a flow transmission cycle is introduced to each wavelength, and each cycle consists of multiple slots, so that flows of different transactions can be multiplexed onto a single wavelength. It is assumed that inter-metropolitan area network (MAN) traffic is transported over wide area network (WAN). A global time-shift scheduling methodology taking into account propagation delays in MAN is designed to avoid potential contentions occurring among different flows which are carried by the same wavelength in WAN. The contributions of this paper are, first it provides a new OFS network architecture which can achieve better throughput and average wavelength utilization performance without losing the feature of simple transport structure provided by OFS; second, it is the first time that issues of how OFS networks are managed and controlled are addressed from a system point of view.


Assuntos
Redes de Comunicação de Computadores/instrumentação , Desenho Assistido por Computador , Dispositivos Ópticos , Processamento de Sinais Assistido por Computador/instrumentação , Desenho de Equipamento , Análise de Falha de Equipamento
14.
Opt Express ; 18(20): 21376-85, 2010 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-20941034

RESUMO

A block-ciphered (M-ary) optical code division multiplexing (OCDM) can provide larger security than a conventional OCDM system based on bit ciphering. We propose a polarization multiplexed (POL-MUX) M-ary OCDM system and demonstrated 2.5 Gbps, POL-MUX 256 ( = 16X16)-ary OCDM transmission using a single multi-port optical encoder/decoder (E/D). We show that this architecture reduces the number of required optical codes and enhances the system confidentiality.

15.
J Nanosci Nanotechnol ; 10(3): 1626-34, 2010 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-20355549

RESUMO

Highly integrated optical device technology based on square-lattice Si-pillar photonic-crystal-(PC) waveguides is described. The Si-pillar PC waveguides are now ready to use, since efficient optical coupling structures to Si-wire waveguides have been devised. Nanophotonic switches using the Si-pillar-PC waveguides were experimentally demonstrated. The nanophotonic switches make use of two of the features of Si-pillar photonic crystal waveguides. One is the property of slow-light and the other is the usability of zero-radius 90 degrees bends, both of which enable waveguide-based optical devices to be greatly miniaturized. Even apart from the cut-off wavelength, the group index of the pillar-PC waveguides was about 7.8, which was about twice that of a Si-wire waveguide for the entire C-band of telecommunications wavelengths. The 3-dB couplers we fabricated were only 3.2-microm long thanks to the 90 degrees sharp bends, and they operated throughout the entire C-band. Waveguide-cross operation was also demonstrated in the entire C-band. Asymmetric Mach-Zehnder interferometers (MZIs) were configured by using the 3-dB couplers in an area of 13.2 x 37.2 microm. An MZI with a Si-wire heater successfully operated with an extinction ratio of about 20 dB at a heating power of 17 mW. It is strongly suggested that Si-pillar PC photonic-waveguide technology should help us to achieve densely integrated optical-matrix switches demanded for future photonic-telecommunication systems.

16.
Opt Express ; 17(26): 23380-8, 2009 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-20052045

RESUMO

Multimode interference (MMI) waveguide switches show promise for switch in optical packet switching (OPS). In this work, we fabricated 1 x 4 InGaAsP/InP MMI waveguide switch device which consists of a 1 x 4 MMI splitter, 4 equally spaced single-mode waveguides with phase shifters, and a 4 x 4 MMI combiner. Good crosstalk and extinction ratio of -14.47 dB and 23.39 dB, respectively, are obtained. In addition, we experimentally demonstrate dynamic switching, and the rise and fall time of 1.4 ns and 1.2 ns, respectively, are obtained.


Assuntos
Arsenicais/química , Índio/química , Dispositivos Ópticos , Fosfinas/química , Refratometria/instrumentação , Processamento de Sinais Assistido por Computador/instrumentação , Desenho Assistido por Computador , Desenho de Equipamento , Análise de Falha de Equipamento
17.
Opt Lett ; 33(21): 2461-3, 2008 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-18978887

RESUMO

A novel implementation of quantum-noise optical cryptography is proposed, which is based on a simplified architecture that allows long-haul, high-speed transmission in a fiber optical network. By using a single multiport encoder/decoder and 16 phase shifters, this new approach can provide the same confidentiality as other implementations of Yuen's encryption protocol, which use a larger number of phase or polarization coherent states. Data confidentiality and error probability for authorized and unauthorized receivers are carefully analyzed.

18.
Opt Express ; 16(15): 11487-95, 2008 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-18648469

RESUMO

We demonstrated, for the first time, a field trial of 160 (16 lambda x 10) Gbit/s, fine granularity, DWDM-based optical packet switching and transmission by newly-developed burst-mode EDFAs and an optical packet switch prototype with multiple all-optical label processors. We achieved 64 km field transmission and switching of 160 (16 lambda x 10) Gbit/s DWDM-based optical packets encapsulating almost 10 Gbit/s IP packets with error-free operation (IP-packet-loss-rate <10(-6) and bit-error-rate <10(-9)).


Assuntos
Desenho Assistido por Computador , Modelos Teóricos , Óptica e Fotônica/instrumentação , Processamento de Sinais Assistido por Computador/instrumentação , Telecomunicações/instrumentação , Simulação por Computador , Desenho de Equipamento , Análise de Falha de Equipamento , Luz , Projetos Piloto , Espalhamento de Radiação
19.
Opt Express ; 16(4): 2570-7, 2008 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-18542338

RESUMO

A complete set of all-optical logic gate operations using a nonlinear-optical-loop-mirror-based multi-periodic transfer function is proposed. This scheme can operate all of sixteen two-input logic operations without changing configuration. We experimentally demonstrate AND, NAND, OR, NOR, XOR, and XNOR operations at 40 Gbit/s in a single configuration. We investigate the limitation of processing speed, and numerical simulation will show the feasibility of the processing speed up to 350 Gbit/s.

20.
Opt Express ; 16(6): 3566-76, 2008 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-18542449

RESUMO

The emerging transparent optical networks, employing spectrally-efficient modulation formats require new methods for supervision of signal quality in the optical domain. In this paper we demonstrate the optical performance monitoring (OPM) of optical signal-to-noise ratio (OSNR) and chromatic dispersion (CD) in return-to-zero differential phase-shift keying (RZ-DPSK) signals using asynchronous delay-tap sampling and pattern recognition algorithms. We experimentally show noise measurement of OSNR from 8.7 dB to 32 dB with low optical input power requirement. Moreover, residual CD can be evaluated in the range from -600 to +600 ps/nm. The results indicate that careful adjustment of delay is necessary in order to ensure accurate measurement.


Assuntos
Algoritmos , Comunicação , Redes de Comunicação de Computadores , Tecnologia de Fibra Óptica/instrumentação , Reconhecimento Automatizado de Padrão/métodos , Processamento de Sinais Assistido por Computador/instrumentação , Desenho de Equipamento , Análise de Falha de Equipamento
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