A terahertz optical asymmetric demultiplexer (TOAD)

A device capable of demultiplexing Tb/s pulse trains that requires less than 1 pJ of switching energy and can be integrated on a chip is presented. The device consists of an optical nonlinear element asymmetrically placed in a short fiber loop. Its switching time is determined by the off-center position of the nonlinear element within the loop, and therefore it can use the strong, slow optical nonlinearities found in semiconductors, which all other fast demultiplexers seek to avoid. The switch's operation at 50 Gb/s is demonstrated, using 600-fJ control pulses     

Monolithically integrated 40-gb/s switchable wavelength converter

An all-optical switchable wavelength-converting module at 40 Gb/s line rate is demonstrated in a fully integrated InP chip. The device combines a semiconductor optical amplifier-based wavelength converter and a fast-tunable multifrequency laser. Sub-nanosecond switching among the eight channels of the integrated laser is shown, and error-free operation of the wavelength conversion process at 40 Gb/s for each wavelength is demonstrated. The applications of fast switching wavelength conversion for optical switching and packet routing are discussed.     

Semiconductor monolithic wavelength selective router using agrating switch integrated with a directional coupler

A semiconductor monolithic wavelength selective router is proposed. An electrically tunable grating switch is monolithically integrated with a directional coupler. The effect of sidelobe on the demultiplexing characteristics of the router is investigated, and it is shown that the sidelobes degrade the wavelength crosstalk and introduce a power penalty for demultiplexing characteristics. A phase-synchronized sampled grating is introduced to suppress the sidelobes, and wavelength router switching is observed in this structure. The extinction ratio is over 10 dB at a current injection of 25 mA. Using this structure, power-penalty-free wavelength selective routing at a 2.5 Gb/s wavelength-division-multiplexed NRZ random pattern is demonstrated     

基于非线性极化旋转技术的640G全光解复用

考虑超快载流子动态特性,文章通过仿真详细分析了基于半导体光放大器的非线性极化旋转效应实现640Gb/s到80Gb/s的解复用方案.结果表明:开关窗口的上升沿随时钟脉冲能量的变化不是很明显,而FWHM和下降沿则随时钟脉冲能量的增加而增加.此外,在相同条件下,当输入的时钟信号为TE模式时,输出的解复用信号具有最高的信道压制比.     

160-Gb/s all-optical demultiplexing using a gain-transparentultrafast-nonlinear interferometer (GT-UNI)

We report on an all-optical demultiplexer based on gain-transparent operation of a semiconductor optical amplifier (SOA) in an ultrafast-nonlinear interferometer (GT-UNI). The GT-UNI comprises a robust fiber-chip setup in a folded geometry. For switching window widths of 5.2 ps and 6.0 ps, error-free demultiplexing of 160-10 Gb/s is demonstrated     

Comparison of gain clamped and conventional semiconductor optical amplifiers for fast all-optical switching

This paper reports computer simulation results to compare a Mach-Zehnder interferometer (MZI) when the two arms of it operate with gain-clamped and conventional semiconductor optical amplifiers (gcSOA and convSOA, respectively) for fast all-optical switching. The comparison is for demultiplexing optical pulses from 160 Gb/s to the base rate of 10 Gb/s or 40 Gb/s. The gain dynamics of the gcSOA is presented, the switching windows at the drop port of the MZI for both cases that were referred before and finally an evaluation of them is discussed.     

Optical demultiplexing at 6 Gb/s using a semiconductor laser amplifier as an optical gate

A semiconductor laser amplifier (SLA) has been employed successfully for optical demultiplexing in two-channel optical time division multiplexed system experiments at 6 and 2 Gb/s. Demultiplexing of 6-Gb/s (2-Gb/s) signals was demonstrated with a power penalty of 1.6 dB (3.0 dB) at bit error rates of 10/sup -9/. It is also shown that a reduction of the generated amplified spontaneous emission can be obtained by optical gating/demultiplexing for systems incorporating inline amplifiers. A 0.5-dB improvement in sensitivity was achieved as a result of using an SLA for demultiplexing from 2.0 to 1.0 Gb/s in a system with one inline Er/sup 3+/-doped fiber amplifier.<>     

SLALOM: semiconductor laser amplifier in a loop mirror

The processing of optical signals in the optical domain is an important issue resulting from the desire to take advantage of the full bandwidth of the optical fiber. In this paper, we present detailed investigations on a device, which utilizes a semiconductor laser amplifier in a loop mirror configuration (SLALOM). Different modes of operation are reported like nonlinear single pulse switching and two-pulse switching at different operation speeds (1-100 Gb/s). Furthermore, a number of applications of the SLALOM in photonic systems, like pulse shaping, decoding, retiming and time-division demultiplexing, are presented. In addition, the SLALOM can be used for an estimate of the linewidth enhancement factor α and the carrier lifetime τ _e in an SLA     

Nonlinear Sagnac interferometer switch and its applications

Ultrafast all-optical switching based on the optical Kerr effect in a Sagnac interferometer which consists of a dichroic polarization-maintaining fiber coupler and dispersion-shifted polarization-maintaining fiber loop is reported. This nonlinear Sagnac interferometer switch has the advantage of high stability originating from completely balanced interfering arms. In addition, because dispersion-shifted fibers were used, increases in switching power and switching time were prevented. Moreover, polarization fluctuation was completely suppressed due to the all-polarization maintaining fiber configuration. The required switching power for complete switching was measured to be 1.8 W for a 200-m-long fiber. All-optical time division demultiplexing and logic operations, including inversion and operation, using the nonlinear Sagnac interferometer switch were successfully demonstrated at 5 Gb/s     

All-optical TDM data demultiplexing at 80 Gb/s with significant timing jitter tolerance using a fiber Bragg grating based rectangular pulse switching technology

We demonstrate the use of fiber Bragg grating based pulse-shaping technology to provide timing jitter tolerant data demultiplexing in an 80 Gb/s all-optical time division multiplexing (OTDM) system. Error-free demultiplexing operation is achieved with /spl sim/6 ps timing jitter tolerance using superstructured fiber Bragg grating based 1.7 ps soliton to 10 ps rectangular pulse conversion at the switching pulse input to a nonlinear optical loop mirror (NOLM) demultiplexer comprising highly nonlinear dispersion shifted fiber (HNLF). A 2-dB power-penalty improvement is obtained compared to demultiplexing without the pulse-shaping grating.     

Optical signal processing for optical packet switching networks

Optical packet switching promises to bring the flexibility and efficiency of the Internet to transparent optical networking with bit rates extending beyond that currently available with electronic router technologies. New optical signal processing techniques have been demonstrated that enable routing at bit rates from 10 Gb/s to beyond 40 Gb/s. We review these signal processing techniques and how all-optical-wavelength converter technology can be used to implement packet switching functions. Specific approaches that utilize-ultra-fast all-optical nonlinear fiber wavelength converters and monolithically integrated optical wavelength converters are discussed and research results presented.     

Ultrafast time-division demultiplexer based on electrooptic on/offgates

Electrooptic on/off gate-based demultiplexers for high-bit-rate optical transmission systems are reported. The electrooptic demultiplexing of a TDM 49.6 Gb/s fixed pattern data stream is demonstrated, using two cascaded Ti:LiNbO₃ electroabsorptive multi-quantum-well intensity modulators driven at 6.2 GHz. Error-free 10 Gb/s demultiplexing to 5 Gb/s is achieved using cascaded Mach-Zehnder (MZ) modulators driven at 1.25 GHz. The power penalty due to the interchannel crosstalk is 0.3 dB at the bit error rate of 10^-9     

160 Gb/s variable length packet/10 Gb/s-label all-optical label switching with wavelength conversion and unicast/multicast operation

We report on the first demonstration of all-optical label switching (AOLS) with 160 Gb/s variable length packets and 10 Gb/s optical labels. This result demonstrates the transparency of AOLS techniques from previously demonstrated 2.5 Gb/s to this 160 Gb/s demonstration using a common routing and packet lookup framework. Packet forwarding/conversion, optical label erasure/re-write and signal regeneration at 160 Gb/s is achieved using a WDM Raman enhanced all-optical fiber cross-phase modulation wavelength converter. It is also experimentally shown that this technique enables packet unicast and multicast operation at 160 Gb/s. The packet bit-error-rate is measured for all optical label switched 16 /spl times/ 10 Gb/s channels and error free operation is demonstrated after both label swapping and packet forwarding.     

20 Gb/s optical soliton data transmission over 70 km usingdistributed fiber amplifiers

20 Gb/s optical soliton data transmission is demonstrated over 70 km. Highly efficient distributed Raman amplifiers for fiber-loss compensation are realized by using high Δn dispersion-shifted single-mode fibers pumped by laser diodes. To achieve high bit rate transmission, optical multiplexing and demultiplexing techniques are also employed. The bit error rate (BER) performance dependence on the input peak power of the optical pulse is measured. No power penalty can be seen at the input peak power required for transmitting optical solitons while the BER performance degrades when decreasing the input peak power     

Signal-to-noise ratio analysis of 100 Gb/s demultiplexing usingnonlinear optical loop mirror

This paper investigates experimentally and theoretically the signal-to-noise ratio (SNR) characteristics of 100 Gb/s all-optical demultiplexing using a nonlinear optical loop mirror (NOLM). The analysis takes into account two effects that degrade the SNR associated with NOLM demultiplexing. First is channel crosstalk originating from the leakage of nontarget channels. Second is the intensity fluctuations of demultiplexed signals caused by the combined effects of timing jitter and a profile of the switching window. Considering these two effects, power penalties associated with NOLM. Demultiplexing are theoretically evaluated using the conventional noise theory of an optical receiver followed by an optical preamplifier. Experimental results of bit error rate measurements for 100 Gb/s demultiplexing using three different NOLMs with different intrinsic crosstalk values, defined by signal transmittance in the absence of control pulses, show that the power penalties are in good agreement with the evaluation based upon our proposed analysis. It can be found from our investigation in demultiplexing from 100 to 10 Gb/s that intrinsic crosstalk of less than -25 dB, corresponding to a coupling ratio, K, of |K-0.5|⩽0.03, is required for the power penalty of less than 1 dB. The root-mean-square (rms) value of the relative timing jitter necessary for obtaining a sufficient timing tolerance width for combining control and signal pulses is determined     

Photonic access concentrator for ATM gigabit switching fabrics

In future broadband communication networks the interest for purely photonic switches is due to the bandwidth mismatch between optical transmission networks and electronic switching nodes. Photonic ATM switching fabrics mainly based on wavelength-switching stages are therefore being studied, to implement high capacity switches with also concentration, multiplexing and demultiplexing functions, using state-of-the-art photonic technology. The architecture of an ATM photonic access concentrator is described in this paper, illustrating the design and implementation of its basic subsystems, the traffic concentrator and the cell multiplexer. The design guidelines are outlined in detail referring to an example, where 128 user lines at 622 Mb/s are given access to 4 outlets at 2.488 Gb/s. The corresponding implementation, based on the systematic use of cell wavelength encoding, makes use either of well-known photonic components, such as Fabry-Perot filters, fiber delay lines, splitters and combiners, either of recently developed devices, like high-speed optical gates and tunable filters and lasers. Finally, the system feasibility is demonstrated presenting the results obtained on a reduced size and speed experimental setup of the cell multiplexer     

Two-stage Sagnac demultiplexer

Cascading a semiconductor optical amplifier (SOA)-based Sagnac interferometer with a second Sagnac stage allows significant improvement in the overall demultiplexer performance. A theoretical analysis and simulations show that the exploitation of a two-stage architecture results in a demultiplexing window sharpness and time compression. Eye-diagram and Q-factor experimental characterization at 2.5 Gb/s of the demultiplexer is presented, showing a 25% compression in time of the two-stage switching window and a 4.7 Q-factor improvement.     

Effects of group velocity dispersion on self/cross phase modulationin a nonlinear Sagnac interferometer switch

Time-resolved numerical analysis of a nonlinear Sagnac interferometer switch (NSIS) reveals that the combined effects of group velocity dispersion (GVD), self phase modulation, cross phase modulation, and pump-probe walk-off seriously degrade switching performance when the soliton number N of the pump pulse is under 5. This means that the peak power of short pump pulses cannot be reduced to less than the critical value at N>5 to prevent the effect of GVD. This restriction is more severe for pump pulses in the anomalous dispersion region than for those in the normal dispersion region because of higher-order soliton compression. System designs for time-division demultiplexers that use NSISs and picosecond pump pulses generated by a laser-diode coupled to erbium-doped fiber amplifiers are discussed. It is found that 1:32 demultiplexing from 160 to 5 Gb/s and 1:8 demultiplexing from 80 to 10 Gb/s with a switching contrast of more than 60 are possible using diode-laser-pumped 1- and 2-ps pump pulses, respectively     

基于三波长SLA的全光解复用器

工作在三波长状态下的SLA作为非线性元件,在光环形镜中实现OTDM信号的解复用,模拟计算表明,在保持光束功率为1W时,SLA恢复时间小于10ps,可从OTDM复用信号中提取出任一路信号,在控制脉冲功率为900mW时,带宽可达100GHz。     

A Hybrid OTDM Scheme With Enhanced Demultiplexing Performance

We propose a novel hybrid optical time-division multiplexing (OTDM) approach, which contains hybrid modulation formats of return-to-zero on-off keying and return-to-zero differential-phase-shift keying, and investigate its demultiplexing performance. Compared with conventional OTDM with homogenous modulation format, the target demultiplexed channel in a hybrid OTDM signal suffers from much less degradation due to the possible crosstalk from the adjacent channels. We experimentally demonstrate 84.88- to 10.61-Gb/s hybrid OTDM demultiplexing and achieve a relatively wide switching window, which cannot be realized by using the conventional OTDM. Moreover, experimental results at 42.44 Gb/s show a much larger tolerance against timing misalignment in demultiplexing, which further validates the improved demultiplexing performance by using the hybrid OTDM scheme.