高消光比超短脉冲产生的实验研究

实验研究了一种高消光比短脉冲的产生技术。利用色散补偿光纤线性压缩由增益开关分布反馈激光器出射的光脉冲。而后利用电吸收调制器的非线性吸收特性同步调制光脉冲。利用这种方法在实验上产生了重复频率为10GHz，脉宽为10．4ps，抖动小，高消光比，无基座的短脉冲。此种技术可以应用于40Gbit／s的光时分复用系统中，同时也说明电吸收调制器具有同号脉冲整形功能。     

200 Gbit/s, 100 km time-division-multiplexed optical transmissionusing supercontinuum pulses with prescaled PLL timing extraction andall-optical demultiplexing

A single channel, single polarisation 200 Gbit/s time-division-multiplexed optical transmission experiment is successfully demonstrated using optical short pulses generated by supercontinuum. A prescaled clock is recovered directly from the 200 Gbit/s signal to drive an all-optical demultiplexer     

Pulse-width tunable, self-frequency conversion of short opticalpulses over 200 nm based on supercontinuum generation

Self-frequency conversion of ultrashort optical pulses into arbitrary multiwavelength components without the use of a pump is achieved by using supercontinuum generation. Frequency conversion of a randomly-modulated 1.535-1.560 μm, 2.5 ps pulse stream at 6.3 Gbit/s into 1.41-1.64 μm, 0.29-1.0 ps pulse streams is demonstrated for the first time. The method features ultrawide tunability of over 200 nm, and multiwavelength, pulsewidth-tunable output for flexible WDM distribution networks     

Applications of single and dual gate GaAs MESFETs for Gbit/s optical data transfer systems

Intrinsic large signal rise and fall times of less than 30 ps without charge storage demonstrate the potential of single and dual gate GaAs MESFETs for Gbit/s optical communication systems. The applications as signal regenerator, bit synchronizer, laser modulator, multiplexer, and demultiplexer are shown. Using only one dual gate GaAs MESFET clock and pulse shape regeneration as well as 1 Gbit/s laser modulation is performed. Bit synchronization is demonstrated up to 4 Gbit/s. 1 to 2 Gbit/s and 2 to 4 Gbit/s multiplexing as well as 2 to 1 Gbit/s demultiplexing with additional clock and pulse shape regeneration is shown using dual gate FETs. 2 to 4 Gbit/s multiplexing without clock regeneration is also accomplished using single gate GaAs MESFETs.     

Multi-WDM-channel, Gbit/s pulse generation from a single lasersource utilizing LD-pumped supercontinuum in optical fibers

More than 40 wavelength-division-multiplexed (WDM) channels of 5-10 ps pulse streams are generated over 1530-1570 nm at 6.3 Gbit/s from a single laser source utilizing laser-diode (LD)-pumped supercontinuum in optical fibers for the first time. The time-bandwidth products of the generated pulses are within the range of 0.3-0.6, and it has been verified that the generated WDM picosecond pulses are capable of being interleaved to produce up to 40 WDM channels, each consisting of 50 Gbit/s time-division-multiplexed (TDM) pulse streams, in one optical fiber     

100 Gbit/s optical signal generation by time-divisionmultiplication of modulated and compressed pulses from gain-switcheddistributed feedback (DFB) laser diode

An all-optical spatial time-division multiplexer is demonstrated using fibre-type 2×2 couplers and fibre delay lines. 100 Gbit/s modulated optical signals are successfully generated by 32-times multiplication of 3.125 Gbit/s, 6 ps compressed pulses, from a gain-switched DFB laser diode     

Transmission experiment at 3 Gbit/s with close-spaced wavelength-division-multiplexed single-frequency lasers at 1.5 ?m

We report the first fibre-optic transmission experiment employing close-spaced wavelength division multiplexing and high-bit-rate modulation. Experimental results from transmission at 3 Gbit/s over 60 km of single-mode fibre using two wavelength-multiplexed single-frequency distri-buted-feedback lasers are described. The lasers, operating at 1.55 ?m and with a wavelength separation of only 2.9 nm, are each modulated at 1.5 Gbit/s giving a total system capacity of 180 Gbitkm/s.     

Integrated tandem traveling-wave electroabsorption modulators for >100 Gbit/s OTDM applications

Integrated tandem traveling-wave electroabsorption modulators are demonstrated as high-speed optical short pulse generators and demultiplexers for >100 Gbit/s optical time-division-multiplexed systems. The tandem significantly increases the extinction ratio and further compresses the optical pulses in comparison to a single modulator. An extinction ratio of /spl sim/50 dB is achieved while optical pulses of 4-6 ps width at 30-40 GHz are generated.     

Analysis of reduced chirping of semiconductor lasers for improved single-mode-fibre transmission capacity

It is shown that direct modulation of semiconductor lasers yielding optical pulses with an exponential shape corresponds to a nearly chirp-free operation. With such pulses the maximum transmission capacity at ? = 1.55 ?m is about 55 Gbit/s ?km for a nondispersion-shifted single-mode fibre.     

14 Gbit/s optical signal encoding for ? = 1.32 ?m with double pulse drive of a Ti:LiNbO3 waveguide modulator

Optical pulses with time separation corresponding to bit rates of ~ 14 Gbit/s (NRZ) have been produced at ? = 1.32 ?m with a Ti: LiNbO3 broadband travelling-wave directional coupler modulator driven by closely spaced, narrow electrical drive pulses. Resolvable optical pulses with as little as 100 ps separation have been generated.     

Key technologies and system design for various radio over fiber applications

Key technologies and new system designs for various radio over fiber (RoF) applications are proposed and demonstrated. For ultrawideband (UWB) over fiber applications, several UWB pulses generation and distribution methods are carried out. Different kinds of UWB pulses are generated based on cross-polarization modulation methods. For millimeter-wave (mm-wave) wireless applications, a 32 GHz RoF system is demonstrated with microwave frequency sextupling by optical methods. After 20 km SMF transmission, the power penalty of 2.5 Gbit/s downlink service is less than 0.15 dB. It is also suitable to apply dense wavelength division multiplexing (DWDM) technology to RoF system to support numerous base stations (BSs).     

Noise caused by semiconductor lasers in high-speed fiber-opticlinks

Theoretical and experimental results are presented for the signal-to-noise (S/N) ratio caused by mode partition noise, intensity noise, and reflection-induced noise in optical data links. Under given conditions an additional noise source with a S /N ratio of 20 dB will cause a power penalty of 1 dB in order to maintain a 10^-9 bit error rate. From numerical simulations the authors predict the maximum allowable dispersion in the presence of mode partition noise to be approximately 40% of a clock period. This figure is almost independent of bit rate and laser structure and agrees well with the measurements and with results of other workers. Numerical simulations of a buried-heterostructure and a TJS laser were carried out at four bit rates from 565 Mbit/s to 4.5 Gbit/s and the measurements were done at 2.2 Gbit/s using a TJS laser     

Distortion-free amplification of high-speed test patterns up to 100 Gbit/s with erbium-doped fibre amplifiers

A report is made on the first distortion-free optical amplification of high-speed signals up to 100 Gbit/s in an erbium-doped fibre amplifier. The amplifier's high-speed temporal characteristics are measured and compared with those of a semiconductor optical amplifier. The high-speed optical test patterns (repetitive or modulated) were generated from a gain-switched DFB laser using optical spectral filtering, chirp compression and optical time-division multiplexing.<>     

Wired and single sideband wireless service based on a single optical modulator

In order to provide more flexible and convenient service for users in the hybrid transmission network,a novel system using a single optical modulator to provide wired and single side band (SSB) wireless signal was proposed.By combining the application of dual-polarization binary phase shift keying modulator (DP-BPSK),phase shifter and other devices,wired and SSB wireless signals were directly generated to suppress the walk-off effect caused by dispersion,and the effective transmission of 5 Gbit/s SSB wireless signal carried on 40 GHz millimeter wave and 10 Gbit/s wired signal over 65 km single-mode fiber (SMF) were successfully achieved.The experiments show that the application of polarization multiplexing technology and optical subcarrier multiplexing technology can make the signal have a greater improvement in transmission rate and performance,and play an important role in the future broadband communication network.     

啁啾管理调制格式在高速接入网中传输分析

物联网、虚拟现实及人工智能等技术的发展加大了对光纤接入无源光网络带宽的需求,其中调制器成为制约无源光网络带宽的关键因素。结合了直接调制激光器和外调制器各自优势的啁啾管理激光器以产生结构简单、便于集成等特点受到了广泛关注。采用耦合速率方程理论研究了啁啾管理激光器的动力学特性,分析了40 Gbit/s啁啾管理调制格式的产生原理及时频域特性,并在高速无色散补偿接入网中与由外调制器产生的40 Gbit/s非归零调制格式进行了性能对比。结果表明,带宽为48.5 GHz的40 Gbit/s啁啾管理调制格式在1 dB灵敏度代价下所对应的色散容限为215 ps/nm,与非归零调制格式相比其无色散补偿传输距离增加了1.6倍,表现出了强的抗色散能力,在高速接入网中也体现了较高的应用价值。相关结果可为实际系统设计提供理论参考。     

Picosecond pulses (2 ps) from hybrid mode-locked AlGaAs QW lasers with integrated active waveguide cavities

Single ultrashort optical pulses (2 ps with 17.6 GHz repetition rate) have been generated with hybrid mode-locked monolithic GaAs/AlGaAs lasers at lambda =856 nm. Instead of an external cavity, long active waveguides were used as resonators with a roundtrip frequency of 5.9 GHz. Increasing the pump current in the waveguide far above transparency led to 10 ps pulses with a high peak power of 110 mW.<>     

New method for generation of coherent ultrashort optical pulses

A new method for generating coherent ultrashort optical pulses from semiconductor lasers with GRIN short external coupled cavity (GSCCL) by means of sinusoidal direct modulation is proposed. 20 ps coherent ultrashort optical pulses have been obtained; the repetition rate is 730 MHz, and the side mode suppression ratio is more than 35 dB.<>     

Picosecond laser pulses

The broad bandwidth and long storage lifetimes of Nd³⁺: glass and ruby lasers have made possible the generation of picosecond laser pulses having peak powers it excess of one gigawatt and repetition rates in the microwave range. The numerous application areas of these pulses include research in nonlinear optics, transient response of atomic and molecular systems, optically generated plasmas, spectroscopy, ranging, optical information processing, and high-speed photography. This paper reviews several experimental techniques for generating, measuring, and utilizing these ultrashort laser pulses.     

High-speed large-signal digital modulation of a 1.3 ?m InGaAsP constricted mesa laser at a simulated bit rate of 16 Gbit/s

Recently, high-frequency 1.3?m InGaAsP constricted mesa lasers have shown a small-signal ?3 dB bandwidth of more than 15 GHz at 15°C, and have been modulated with pseudorandom pulses at 8 Gbit/s (NRZ format). The letter reports large-signal digital modulation of such a constricted mesa laser using time-multiplexed electrical pulses 80 Ps in duration and 125 Ps apart which demonstrates the high-speed modulation capability of this laser at a simulated bit rate of 16 Gbit/s (NRZ).     

40-Gbit/s TDM transmission technologies based on ultra-high-speedICs

This paper presents 40-Gbit/s time division multiplexing (TDM) transmission technologies based on 0.1-μm-gate-length InP high electron mobility transistor IC's and a scheme for upgrading toward a terabit-per-second capacity system. A 40-Gbit/s, 300-km, in-line transmission experiment and a dispersion-tolerant 40-Gbit/s duobinary transmission experiment are described as 40-Gbit/s single carrier system applications on dispersion-shifted fiber. An ultra-high-speed receiver configuration using a high-output-power photodiode is introduced to realize fully electrical receiver operation beyond 40 Gbit/s. The high-sensitivity operation of the optical receiver (-27.6 dBm@BER=10^-9) is demonstrated at a data bit rate of 50 Gbit/s for the first time using a unitraveling carrier photodiode. A dense wavelength division multiplexing (DWDM) system operating up to terabits per second can be easily realized on a zero-dispersion flattened transmission line using ultra-high speed TDM channels of 40 Gbit/s and beyond. An experiment demonstrates 1.04-Tbit/s DWDM transmission based on 40-Gbit/s TDM channels with high optical spectrum density (0.4 bit/s/Hz) without dispersion compensation