A new scheme for bidirectional WDM-PON using upstream and downstream channels generated by optical carrier suppression and separation technique

We propose a new bidirectional dense wavelength-division-multiplexing (DWDM)-based passive optical network using optical carrier suppression and separation technique to generate both upstream and downstream wavelength channels from a single laser. Thirty-two DWDM channels have been generated, and symmetric 10-Gb/s data transmission of a wavelength pair has been demonstrated.     

1.25 Gbit/s millimetre-wave band wired/wireless radio-over-fibre system based on RSOA using injection-locking effect

A new architecture for a millimetre-wave band radio-over-fibre system is proposed. Both optical carrier suppression and injection locking effect are used to simultaneously generate a 1.25 Gbit/s wired signal and a 63 GHz wireless one. Error-free transmissions (bit error rate of 10^-11) of downlink and uplink data are achieved to verify the proposed scheme. No impact of a downlink data transmission on an uplink one owing to the wavelength reuse is observed. It is checked that there is only the 2 dB power penalty of the uplink owing to the Rayleigh backscattering noise.     

A CMOS burst-mode optical transmitter for 1.25-Gb/s ethernet PON applications

This brief presents a CMOS burst-mode optical transmitter suitable for use in 1.25-Gb/s Ethernet passive optical network applications. Based on feedback from the monitoring photodiode, in order to control consecutive burst data the proposed transmitter in this brief uses a reset mechanism, which allows fast responses from the beginning of a high-speed input burst. The chip is fabricated in mixed-mode 0.18-/spl mu/m CMOS technology and measurements are implemented in a chip-on-board configuration using a pig-tailed type Fabry-Perot laser. Under burst-mode operation of 1.25-Gb/s pseudorandom binary sequences, measurements show about 1-dBm averaged transmitted optical power with an over 12-dB extinction ratio over a wide temperature range.     

An AWG-based 10 Gbit/s colorless WDM-PON system using a chirp-managed directly modulated laser

We propose an arrayed waveguide grating(AWG)-based 10 Gbit/s per channel full duplex wavelength division multiplexing passive optical network(WDM-PON).A chirp managed directly modulated laser with return-to-zero(RZ) differential phase shift keying(DPSK) modulation technique is utilized for downlink(DL) direction,and then the downlink signal is re-modulated for the uplink(UL) direction using intensity modulation technique with the data rate of 10 Gbit/s per channel.A successful WDM-PON transmission operation with the data rate of 10 Gbit/s per channel over a distance of 25 km without any optical amplification or dispersion compensation is demonstrated with low power penalty.     

560 Mbit/s optical PSK heterodyne detection using carrier recovery

An optical PSK heterodyne synchronous detection experiment was performed at a bit rate of 560 Mbit/s using carrier recovery in the IF stage. A receiver sensitivity of -51.6 dBm was achieved, and the power penalty due to the phase noise of the laser diodes was suppressed to less than that of DPSK.<>     

Bidirectional colorless gigabit WDM-passive optical networks by use of injection locking and optical carrier suppression

A new bidirectional wavelength division multiplexed-passive optical network architecture for colorless optical line terminal and optical network unit was proposed by the use of injection locking of Fabry–Perot laser diode and optical carrier suppression. Error free transmissions (bit error rate of 10^?9) of both 1.25-Gb/s downstream signal and upstream signal were experimentally demonstrated at three representative wavelengths (1530.364, 1540.14, and 1556.713 nm). Accordingly, both optical line terminal and optical network unit were colorlessly operated within 25-nm range. Also, there was little impact of leaked channel on adjacent main one.     

Mitigation of interferometric crosstalk by using a single mode laser with optical feedback in a loop-back WDM-PON based on RSOA

To alleviate the back-reflection induced interferometric crosstalk in a loop-back WDM-PON based on RSOA, we propose the use of off-the-shelf single mode operated laser with intentional optical feedback as a seeding source. For adjusting the external optical feedback quantity, we could effectively broaden the spectral linewidth of single mode operated laser output. We also experimentally demonstrated that our proposed method could enhance the up- and down-stream transmission performances under relatively lower signal to crosstalk ratio.     

A 1-Gb/s bidirectional I/O buffer using the current-mode scheme

A current-mode bidirectional I/O buffer was designed, and the maximum effective bandwidth of 1.0 Gb/s per wire was obtained from measurements. To enhance the operating speed, the voltage swing on the transmission line was reduced to 0.5 V and the internal nodes of the buffer were designed to be low impedance nodes using the current-mode scheme. An automatic impedance-matching scheme was used to generate bias voltages, which adjust output resistance of the buffer to be equal to the characteristic impedance of the transmission line in spite of process variations. The chip was fabricated by using a 0.8-μm CMOS technology. The chip size was 500×330 μm², and the power consumption was 50 mW at a supply voltage of 3 V     

10-Gb/s upgrade of bidirectional CWDM systems using electronic equalization and FEC

We discuss options for upgrading coarse wavelength-division multiplexed (CWDM) optical access links over standard single-mode fiber (SSMF) by increasing per-channel data rates from 2.5 to 10 Gb/s. We identify electronic equalization and forward error correction (FEC) as the enabling technologies to overcome the dispersion limit of SSMF. In addition, we show how FEC enhances the tolerance to in-band crosstalk, and paves the way toward fully bidirectional CWDM transmission. Due to the lack of CWDM sources rated for 10-Gb/s operation, we demonstrate full-spectrum (1310 to 1610 nm) 10-Gb/s CWDM transmission over standard-dispersion fiber using uncooled, directly modulated lasers specified for 2.5 Gb/s. All 16 CWDM channels could be transmitted over more than 40 km, yielding a capacity-times-distance product of 6.4 Tb/s/km. The longest transmission distance (80 km) was achieved at 1610 nm, equivalent to 1600 ps/nm of chromatic dispersion.     

5-Gb/s XOR optical gate based on cross-polarization modulation insemiconductor optical amplifiers

We demonstrate a new design for a XOR optical gate operating in the GHz regime using the cross-polarization modulation effect in a semiconductor optical amplifier. Dynamic and optically controlled polarization rotation in the devices is used to control the output power of the device. Static extinction ratio of the order of 20 dB can be obtained. Bit rate doubling at rate of 1.2 and 2.5 Gb/s have been demonstrated     

WDM PON using 10-Gb/s DPSK downstream and re-modulated 10-Gb/s OOK upstream based on SOA

A signal remodulation scheme of 10-Gb/s differential phase-shift keying(DPSK) downstream and 10-Gb/s on-off keying(OOK) upstream using a semiconductor optical amplifier(SOA) and a Mach-Zehnder intensity modulator(MZ-IM) at the optical networking unit(ONU) side for wavelength division multiplexed passive optical network(WDM PON) is proposed.Simulation results indicate that error-free operation can be achieved in a 20-km transmission,and the receiver sensitivity of return-to-zero differential phase-shift keying(RZ-DPSK) is higher than nonreturn-to-zero differential phase-shift keying(NRZ-DPSK) in the proposed scheme.     

40-Gb/s optical 3R regenerator using electroabsorption modulatorsfor optical networks

A 40-Gb/s optical retiming, reshaping, and retransmitting (3R) regenerator was proposed and demonstrated using wavelength converters based on electroabsorption (EA) modulators for effectively implementing 40-Gb/s-based or higher bit rate wavelength division multiplexing (WDM) optical networks. The proposed optical 3R regenerator is configured in a very simple architecture, consisting of two wavelength converters, a clock recovery section, and an optical clock generator section. Furthermore, the stable and polarization-insensitive operation, as well as simple adjustment of an optimal operation condition of our proposed optical 3R regenerator, were confirmed by conducting transmission experiments. To investigate the applicability of optical 3R regenerators to optical networks, it was evaluated by insertion between two 500-km-long segments of transmission line. A Q-factor improvement of about 1.5 dB was obtained after transmission over 1000 km, compared to evaluation without the regenerator. This type of optical 3R regenerator proves extremely useful in future high-speed and scaleable all-optical networks     

Radiometric Millimeter-wave detection via optical upconversion and carrier suppression

We report a novel technique for radiometric detection of radiation in the millimeter-wave regime based on optical modulation. Millimeter-wave energy modulated onto an optical carrier is detected using a low-bandwidth photodetector with optical filtering to suppress the carrier. Using this technique, we have achieved noise-equivalent powers as low as 20 pW/spl radic/Hz for a 44-GHz narrow-band signal using chopping techniques. Such detection was implemented using commercially available components and without RF or optical amplification. Further improvements in sensitivity are expected as the setup is optimized for operation in the frequency band of interest.     

Rayleigh Backscattering Noise-Eliminated 115-km Long-Reach Bidirectional Centralized WDM-PON With 10-Gb/s DPSK Downstream and Remodulated 2.5-Gb/s OCS-SCM Upstream Signal

We propose a novel scheme of Rayleigh backscattering noise-eliminated, long-reach, single-fiber, full-duplex, centralized wavelength-division multiplexed passive optical network with differential quadrature phase-shift keying (DPSK) downstream and remodulated upstream using an optical carrier-suppressed subcarrier-modulation (OCS-SCM) technique and optical interleaver. The error-free transmissions of 10-Gb/s downstream and 2.5-Gb/s upstream signals are experimentally demonstrated over 115-km single-fiber bidirectional SMF-28 with less than 0.5 and 1.9 dB power penalties, respectively.      

基于光载波抑制的光标记交换新技术

介绍一种新的光标记交换技术,它是利用光载波的抑制来产生具有固定频率间隔的双波长光波,并对这两路光波分别进行调制,以加载光标记和光数据载荷.在网络的节点处使用波长变换技术进行标记交换.该技术结构简单,易于实现,克服了现有的光标记交换技术中的一些不足之处.     

一种基于光载波抑制的ROF双工系统

为克服远距离光纤传输系统中色散效应的影响,研究了一种基于光载波抑制的单工ROF(光纤无线电)系统,并提出改进的双工ROF系统传输方案。在中心站,采用20GHz的射频信号将下行链路信号耦合至光载波抑制频段处,通过单模光纤传输50km至基站,并重复利用未调制边带传输上行链路信号。通过仿真得到的系统光谱图和误码率曲线表明:加入上行链路信号传输后,下行链路的光纤能量损耗降低,上、下行链路同时具有较好的抗色散能力。     

80-Gb/s wavelength conversion based on cross-phase modulation inhigh-nonlinearity dispersion-shifted fiber and optical filtering

Using cross-phase modulation in a 1-km high-nonlinearity dispersion-shifted fiber with subsequent filtering by a tunable optical filter, 80-Gb/s pulsewidth maintained wavelength conversion is realized. Penalty-free transmission over 80-km conventional single-mode fiber and 12-km dispersion-compensating fiber for 80-Gb/s converted signal is realized     

Extended-reach WDM-PON based on CW supercontinuum light source for colorless FP-LD based OLT and RSOA-based ONUs

We investigate the benefits of using our proposed continuous-wave supercontinuum (CW SC) as a broadband wavelength-locking source for the implementation of extended-reach, colorless, wavelength division-multiplexed passive optical networks (WDM-PONs). More specifically, first, an extended reach WDM-PON architecture based on both the CW SC and our devised C-/L-band beam combiner is proposed, in which the optical line terminal (OLT) is based on Fabry–Pérot laser diodes (FP-LDs), whereas the optical network units (ONUs) are reflective semiconductor optical amplifiers (RSOAs). Second, a theoretical investigation on the maximum reach achievable with the proposed architecture is carried out considering Rayleigh backscattering noise and injection power limits. Only upstream signal performance is compared for the following four cases: (1) superluminescent diode (SLD) broadband source and FP-LD ONU, (2) SLD and RSOA, (3) CW SC and FP-LD, and (4) CW SC and RSOA. The combination of a CW SC injection source and RSOA-based ONUs is found to allow for the longest distance coverage. Finally, the feasibility of the proposed architecture is experimentally analyzed over a 60-km transmission fiber at 622 Mbit/s.     

基于RSOA再调技术40Gb/s传输系统研究

下一代接入网的发展趋势是WDM-PON(波分复用无源光网络),基于反射式半导体光放大器(RSOA)再调制的无色ONU技术降低WDM-PON成本与结构简化,因而具有较强的市场潜力。DPSK具有恒功率特性且抗干扰性能显著,常优先选作系统调制方式。在不断追求高速率、大容量的时代,单信道40Gb/s的光传输系统的研究就极具有意义。利用OptiSystem软件,仿真了基于RSOA的40Gb/s传输系统,分析了RSOA的增益特性与系统性能,最后验证了DPSK在基于RSOA的高速PON中应用的可行性。     

A full-duplex radio-over-fiber system based on optical carrier suppression and reuse

We have experimentally demonstrated a full-duplex radio-over-fiber system using a single light source at central station (CS). Optical carrier suppression modulation scheme was employed to generate 40-GHz optical millimeter wave and up-convert the baseband signal simultaneously at CS for downlink transmission while the same optical carrier was reused at base station for uplink connection. The bidirectional full-duplex 2.5-Gb/s data was successfully transmitted over 40-km standard single-mode fiber (SMF-28) for both upstream and downstream channels with less than 2-dB power penalty. This system shows simple cost-efficient configuration and good performance over long-distance delivery.