Optical time-division multiplexed transmission system experiment at 8 Gbit/s

We describe the design and performance of an experimental two-channel optical time-division multiplexed fibre transmission system operating at a wavelength of 1.3 ?m and a bit rate of 8 Gbit/s. Transmission over 8 km of single-mode fibre with low crosstalk and transmission error rates as low as 10?10 is demonstrated.     

Straight-line soliton data transmission at 20 Gbit/s beyondGordon-Haus limit

Soliton data signals at 20 Gbit/s have been successfully transmitted over 3000 km with the use of soliton control by synchronous modulation and optical filters. The installation of only one simple modulator makes it possible to extend the maximum transmission distance from 2300 km (without soliton control) to 3000 km which is clearly beyond the Gordon-Haus limit     

Simultaneous 45.2 Gbit/s 4-PAM data and 8 GHz reference frequency clock signal transmission over DWDM VCSEL channels for optical interconnects

In this paper, we propose and experimentally demonstrate a vertical cavity surface emitting laser (VCSEL)-based simultaneous 45.2 Gbit/s (2×22.6 Gbit/s) 4-PAM data and 8 GHz (2×4 GHz) phase modulated reference frequency (RF) clock signal transmission dense wavelength division multiplexing (DWDM) system for optical interconnects. Two low-cost power-efficient 10 G VCSEL channels with central wavelengths at 1 550.71 nm and 1 551.11 nm are separately modulated with 22.6 Gbit/s 4-PAM data, therefore doubling the channel bit rate. Carrier spectral efficiency per channel is further maximized by exploiting the phase attribute in transmission of a 4 Hz RF clock signal. To further maximize the network capacity, the two VCSEL channels are densely multiplexed at 0.4 nm spacing. We therefore experimentally achieve the network data rate of 45.2 Gbit/s with 8 GHz phase modulated RF clock signal. The results show that receiver sensitivities of ?11.02 dBm and ?9.98 dBm are experimentally achieved for VCSEL channels of 1 550.71 nm and 1 551.11 nm respectively without the phase modulated RF clock signal. However, the introduction of a phase modulated clock signal contributes to a maximum interference penalty of 0.57 dBm and 0.41 dBm for the considered channels respectively. Simultaneous distribution of transmission data and reference clock signal over shared network structure maximizes the carrier spectral efficiency and network capacity with low cost.     

160 Gbit/s soliton data transmission over 200 km

Polarisation- and time-domain-multiplexed 160 Gbit/s soliton signals have been successfully transmitted over 200 km for the first time. The soliton source was a 10 GHz regeneratively modelocked fibre laser and a planar lightwave circuit was used for optical multiplexing. The soliton pulse width was ~1.5 ps. A polariser and a nonlinear loop mirror were used for demultiplexing from 160 to 10 Gbit/s     

8 Gbit/s transmission over 30 km of optical fibre

We demonstrate, for the first time, 8 Gbit/s digital transmission over single-mode optical fibre. A 30 km link was achieved using a directly modulated 1.31 ?m multilongitudinal-mode laser and an avalanche photodiode receiver.     

FSK heterodyne transmission experiments at 560 Mbit/s and 1 Gbit/s

Optical frequency-shift-keying (FSK) signals are obtained from directly modulated distributed feedback (DFB) semiconductor lasers. Experimental studies of the direct frequency modulation (FM) characteristics of the DFB lasers show a nonuniform FM response due to the competing effects of thermal modulation of the laser active region and carrier density modulation. Equalization of the signal current to the laser is employed to produce a flat FM response from 30 kHz to 1 GHz. Optical FSK transmission and heterodyne detection experiments at 560-Mbit/s and 1-Gbit/s are conducted at a wavelength of 1497 nm. Receiver sensitivities of -39 dBm at 560 Mbit/s and -37 dBm at 1 Gbit/s are obtained. Transmission through 100 km of single-mode fiber at 1 Gbit/s is achieved with no degradation in receiver sensitivity.     

10‐Gbit/s Wireless Communication System at 300 GHz

A 10‐Gbit/s wireless communication system operating at a carrier frequency of 300 GHz is presented. The modulation scheme is amplitude shift keying in incoherent mode with a high intermediate frequency (IF) of 30 GHz and a bandwidth of 20 GHz for transmitting a 10‐Gbit/s baseband (BB) data signal. A single sideband transmission is implemented using a waveguide‐tapered 270‐GHz highpass filter with a lower sideband rejection of around 60 dB. This paper presents an all‐electronic design of a terahertz communication system, including the major modules of the BB and IF band as well as the RF modules. The wireless link shows that, aided by a clock and data recovery circuit, it can receive 2⁷?1 pseudorandom binary sequence data without error at up to 10 Gbit/s for over 1.2 m using collimating lenses, where the transmitted power is 10 μW.     

10 Gbit/s pseudorandom dark soliton data transmission over 1200 km

A 10 Gbit/s pseudorandom (PR) dark soliton data signal has been successfully transmitted over 1200 km for the first time. The dark soliton source was a 1.53 μm DFB LD and was modulated with a push-pull Mach-Zehnder LiNbO₃ intensity modulator. A T-flip-flop circuit was used to generate the PR dark soliton. A one-bit-shifting scheme with a Mach-Zehnder interferometer was used to convert the dark soliton train into a conventional NRZ signal     

NTT ultra-fast,large-capacity optical transmission at 400 Gbit/s

By combining optical time-division-multiplexing (TDM) and wavelength division-multiplexing (WDM) with a single super-continuum light source NTT Corp. has successfully conducted an ultra-fast, large-capacity optical transmission experiment at 400 Gbit/s (equivalent to sending 100 years of newspapers in a second) over a distance of 100 km. Having already confirmed that the PLL timing extraction circuit and all optical time-division demultiplexer are able to function at 400 Gbit/s and 200 Gbit/s, respectively, NTT plans to continue R&D efforts to develop an optical transmission system exceeding 1 T bit/s.     

1 Tbit/s km transmission experiment at 16 Gbit/s using conventional fibre

Describes a single-channel optical transmission experiment that achieved a bit rate-distance product of 1 Tbit/s km over conventional (non-dispersion-shifted) fibre. The transmitter was a directly modulated, 1.3 mu m-wavelength, distributed feedback laser. The receiver employed a semiconductor optical preamplifier and a high-impedance pinHEMT front-end.<>     

Bipolar optical FSK transmission experiments at 150 Mbit/s and 1Gbit/s

Bipolar direct modulation has been used to overcome the nonuniform low-frequency modulation response of distributed-feedback laser transmitter in optical FSK transmission experiments at 150 Mb/s and 1 Gb/s. The heterodyne receiver sensitivity was -48 dBm for 150 Mb/s and -39 dBm for Gb/s, independently of the pseudorandom pattern length. There was no degradation in receiver sensitivity with transmission through more than 100 km of fiber     

Optical time-division multiplexed transmission at 8 Gbit/s using single laser and semiconductor optical power amplifier

The authors report transmission over 57 km of single-mode fibre in a two-channel, 8 Gbit/s optical time-division multiplexed system experiment using a transmitter with a single laser and a semiconductor optical power amplifier at the transmitter output. The amplifier operates with a net gain of 11.5 dB, which corresponds to 0.8 dB gain compression, and a fibre coupled output power of +6 dBm. The amplifier facet output power for which the gain is compressed by 3 dB is +13 dBm. The experimental system uses neither an isolator nor an optical filter.<>     

An APD/FET optical receiver operating at 8 Gbit/s

A high-sensitivity optical receiver has been designed for a bit rate of 8 Gbit/s and wavelengths of1.3-1.55mum. The receiver uses a 60-GHz gain-bandwidth-product InGaAs/InGaAsP/InP avalanche photodiode followed by a high-impedance hybrid GaAs MESFET preamplifier. A bandwidth of 6.9 GHz was measured, with flat frequency response ±2 dB being obtained through the use of a 3-tap transversal equalizer. A sensitivitybar{P}as high as -25.8 dBm was measured for 10^-9bit-error rate.     

40 Gbit/s straight-line RZ data transmission over 240 km ofstandard fibre

The authors report straight-line single-channel 40 Gbit/s RZ data transmission over 240 km of standard fibre with periodic dispersion compensation. To the authors' knowledge, this is the longest transmission distance reported in a straight-line transmission experiment, at 40 Gbit/s without any precoding. The back-to-back receiver sensitivity of the system was 18.9 dBm for a BER of 10^-9 . Transmitting data over 240 km of fibre induced a sensitivity penalty of 0.4 dB for a BER of 10^-9     

Dispersion-supported transmission at 20 Gbit/s over 53 km standardsinglemode fibre

The optical transmission of 20 Gbit/s signals over a record distance of 53 km standard nondispersion-shifted singlemode fibre (SMF) without optical dispersion compensation has been demonstrated successfully using a directly modulated MQW DFB laser operating at 1544 nm     

Unrepeatered 2.4 Gbit/s transmission experiment over 250 km of step-index fibre using erbium power amplifier

An erbium power amplifier is used to give a system launch power in excess of +20 dBm. In conjunction with an FSK modulation technique this allows unrepeatered transmission over 250 km of step-index fibre with a loss of 50 dB and a total dispersion of 3930 ps nm/sup -1/.<>     

360 m 20 Gbit/s的W波段无线通信系统

为了满足未来空间高速通信的迫切需求,进行了W波段(75~110 GHz)无线高速通信的研究。通信系统中采用光子上变频技术产生传输速率为20 Gbit/s的W波段QPSK信号,解决了电子器件带宽受限的瓶颈问题。在接收机端采用模拟下变频和先进数字信号处理技术,实现了无线传输360 m距离后信号的离线解调。最终系统的误码率小于硬判决前向纠错(FEC)门限3.8×10?3。     

Gbit/s lossless data compression hardware

This paper presents the X-MatchPRO high-speed lossless data compression algorithm and its hardware implementation, which enables data independent throughputs of 1.6 Gbit/s compression and decompression using contemporary low-cost reprogrammable field-programmable gate array technology. A full-duplex implementation is presented that allows a combined compression and decompression performance of 3.2 Gbit/s. The features of the compression algorithm and architecture that have enabled the high throughputs are described in detail. A comparison between this device and other commercially available data compressors is made in terms of technology, compression ratio, and throughput. X-MatchPRO is a fully synchronous design proven in silicon specially targeted to improve the performance of Gbit/s storage and communication applications.     

10 Gbit/s transmission over air-guiding photonic bandgap fibre at 1550 nm

The first data transmission over air-guiding photonic bandgap (PBG) fibre is demonstrated. A 10 Gbit/s signal was successfully transmitted at 1550 nm over 150 m of singlemode PBG fibre, thus demonstrating their applicability to optical communications. Furthermore, the impact of the polarisation properties of PBG fibres is highlighted experimentally.     

Demonstration of sliding-filter-controlled soliton transmission at20 Gbit/s over 14 Mm

Soliton transmission of a 20 Gbit/s time/polarisation multiplexed signal over 14 Mm path in a recirculating loop with 46.3 km amplification span has been demonstrated using the sliding-filter soliton control technique. Demultiplexing was achieved by using a polarisation-insensitive electroabsorption modulator