An optical multicast packet switching architecture shared with limited-range multi-wavelength converter and full-range wavelength converters

Optical packet switch with multicast capability can inspire a broad range of multipoint to multipoint applications in future optical networks. An optical multicast packet switching architecture, equipped with feedback shared small number of limited-range multi-wavelength converters (LMWCs) and output shared some full-range wavelength converters (FRWCs), is proposed for a wavelength-division multiplexed optical multicast network to improve multicast performance in the paper. The FRWCs are used to overcome the performance degradation in terms of packet loss probability due to only use LMWCs. In the architecture, the two converters are shared by all the multicast packets importing to the optical multicast switch node. A maximum bipartite matching with minimum edges weights strategy was designed to employ fewer wavelength converters and avoid useless degradation of optical signal quality for the architecture to improve the node performance. The simulation results show that the proposed architecture and its wavelength converter scheduling algorithm can reduce the multicast packet loss probability with relatively lesser wavelength conversion cost.     

Polarization-independent wavelength conversion using a single semiconductor optical amplifier

Polarization-independent wavelength conversion is demonstrated by using four-wave mixing (FWM) in a single semiconductor optical amplifier (SOA). In this scheme, all the incident fields are split into two orthogonal-polarized parts by polarizing beam splitters (PBS). Each of the two parts is then transmitted into one facet of the SOA and they are counter-propagating through the same amplifier. Wavelength conversion with the polarization sensitivity less than 1.3 dB is obtained over a range from 1510 to 1620 nm.     

Ultrabroad-band wavelength converter with high flattening conversion efficiency in a semiconductor optical amplifier

The efficiency of ultrabroad-band wavelength conversion using orthogonal-pump four-wave mixing in a semiconductor optical amplifier is measured for the wavelength shifts from 1500 to 1640 nm. The variation of conversion efficiency is ＜ 0.9 dB over the wavelength range from 1530 to 1560 nm (C-band), and ＜ 4.5dB over the wavelength range from 1560 to 1610 nm (L-band). The maximum conversion efficiency is about -8.7 dB.     

NOLM-based wavelength conversion with FBG band-pass filter for optical packet switching

Nonlinear-optical-loop-mirror wavelength conversion is studied in details. A set of two-phase-shiftedBragg gratings are introduced into the coverter,serving as a narrow band-pass filter to remove newfrequencies generated by walk-off and to compensate the dispersion. Numerical simulations are performedto validate our method. The results show that the converted pulses after the filter are reshaped and,sometimes, even compressed.     

Erbium doped fiber ring laser for optical wavelength conversion

We experimentally investigate the gain saturation effect of a piece of 8 m long Erbium doped fiber (EDF), we introduce a theoretical model for the EDF ring loop, and our simulation results show very good cross-gain modulation (XGM) and wavelength conversion. We also experimentally investigate the XGM in an EDF ring loop system. Based on the study of the XGM in the EDF ring loop system, a wavelength conversion is designed with the EDF ring loop system. The EDF ring loop systems as a wavelength conversion is experimentally demonstrated by converting a sinusoidal modulated optical signal at wavelength of 1551 nm to an optical signal at wavelength of 1553.3 nm.     

Picosecond wavelength conversion using semiconductor optical amplifier integrated with microring resonator notch filter

Optical and Quantum Electronics - In this paper, we analyse the picosecond wavelength conversion using semiconductor optical amplifier (SOA) with a novel technique. For an accurate and precise...     

Characteristics of wavelength conversion of short optical pulses in quantum dot semiconductor optical amplifiers

The characteristics of short optical pulse four-wave mixing (FWM) and amplification in quantum dot semiconductor optical amplifiers (QD-SOAs) are investigated taken into account the effect of the multi-discrete QD energy levels. Different saturation and recovery response for the electron and hole states are observed, which is attributed to different energy spacing between the energy states. We found that the 3 dB saturation energy of QD-SOA depends on the pulse width for short input pulses. Also, the optimum time delay between the probe and pump pulses in QD-SOAs, which provides maximum FWM efficiency in QD-SOAs, is smaller than the optimum delay in quantum well SOA.     

集成双波导半导体光放大器光开关实现波长转换的理论研究

建立了基于集成双波导半导体光放大器的光开关(ITG-SOA-Switch)的理论分析模型.与半导体光放大器(SOA)的特性相比较表明，由于ITG-SOA-Switch合并了多种物理效应，故其静态增益饱和曲线在饱和功率点附近具有大幅度陡峭下降的独特性质.理论分析和10 Gbit/s波长转换模拟结果显示，恰当地选择输入抽运光的功率范围，ITG-SOA-Switch波长转换器输出转换光的消光比特性较之输入抽运光会有显著的改善. 关键词： 波长转换 半导体光放大器 集成双波导半导体光放大器 光开关     

基于半导体光放大器交叉偏振调制的波长转换理论研究

在半导体光放大器中,采用由张应变引起的自身双折射理论模型对交叉偏振调制型全光波长转换器的波长转换特性进行了数值研究,并对数值结果与相关实验进行了对比。结果表明:通过调节系统参量,可以实现同相或反相波长转换;同相和反相波长转换时输出的信号啁啾、消光比和眼图具有不同特性;随着数据传输速率的增加,输出信号的眼图张开度减小,啁啾变大。     

基于光纤中SRS效应的全光波长转换

提出利用光纤中非线性效应受激喇曼散射（stimulated Raman scattering, SRS）实现波长转换的原理方案和相应的理论分析模型,并进行实验验证,将经过放大后的信号光和连续探测光同时注入光纤,在光纤中进行SRS放大,实现信号之间的转换。结果表明:利用SRS可实现波长转换,可实现跨几个THz的波长之间的转换。得到最大转换效率和消光比分别为-17.3 dB和15.7 dB。通过改变探测光的波长,可实现相隔几个THz光信号的全光波长转换和可调谐波长转换。     

基于半导体光放大器和光学滤波器的同相波长转换理论研究

采用半导体光放大器(SOA)级联滤波器的方案可以实现高速全光波长转换,其中,滤波器实质上是对SOA输出信号的光谱进行优化操作.文中利用带通滤波器(BPF)和延时干涉仪(DI)组成的光谱优化器,不仅实现了80Gbit/s同相波长转换,而且基于遗传算法设计光谱优化器的参数,极大地提高了输出信号的质量.同时,也从理论上分析了SOA中超快带内效应对信号光谱的影响以及光谱优化器中BPF和DI的消光比对输出信号质量的影响.     

Continuous-wave fiber optical parametric wavelength converter with +40-dB conversion efficiency and a 3.8-dB noise figure

We have obtained 40 dB of internal (on-off) conversion gain and a sub-4-dB noise figure (NF) with a continuous-wave (cw) fiber optical parametric wavelength converter. To our knowledge, this is the lowest NF reported for any cw wavelength converter. We have also investigated the properties of NF versus signal input power and pump power.     

Simultaneous generation and wavelength conversion of a pulse train from multi-wave mixing in an optical fibre

The insertion of three continuous-wave optical frequencies in a low-dispersion optical fibre resulted in the generation of a high-repetition-rate train of ultra-short pulses and its simultaneous wavelength conversion. Two of the frequencies were spaced by ∼0.17 THz and multi-wave mixing generated a frequency comb to which is associated a train of 1.6 ps pulses. Wave-mixing between the generated comb and the third input optical frequency then converts the pulse train into different wavelengths. The Split-Step Fourier method was applied to numerically simulate the generation/wavelength conversion and results are in good agreement with experiments.     

A novel approach to all-optical wavelength conversion by utilizing a reflective semiconductor optical amplifier in a co-propagation scheme

Nonlinear optical gain modulation in an InGaAsP/InP bulk reflective semiconductor optical amplifier (RSOA) is studied. The differences of the optical properties between RSOAs and conventional SOAs are initially investigated. All-optical wavelength conversion based on nonlinear gain modulation in RSOAs is demonstrated at a bit rate of 2.488 Gbit/s. It is shown that a bit-error-rate of <10⁻⁹ can be achieved and an extinction ratio of >9 dB can be obtained at a bit rate of 2.488 Gbit/s with a 2³¹-1 non-return-to-zero (NRZ) pseudorandom bit sequence (PRBS). In comparison with conventional SOAs, wavelength conversion by RSOAs shows much improved performances in high-speed all-optical wavelength conversions.     

Towards 640 Gbit/s wavelength conversion based on nonlinear polarization rotation in a semiconductor optical amplifier

Taking into account ultra-fast carrier dynamics, this paper models 640 Gbit/s wavelength conversion scheme based on nonlinear polarization rotation （NPR） in a single semiconductor optical amplifier （SOA） and investigates the performance of this kind of wavelength conversion scheme in detail. In this model, two carrier temperature equations are introduced to substitute two energy density equations, which reduce the complexity of calculation in comparison with the previous model. The temporary gain and phase shift dynamics induced by ultra-short optical pulses are numerically simulated and the simulated results are qualitatively in good agreement with reported experimental results. Simulated results show that non-inverted and inverted 640 Gbit/s wavelength conversions based on NPR are achieved with clear open eye diagrams. To further investigate the performance of the non-inverted wavelength conversion scheme, the dependence of output extinction ratio （ER） on some key parameters used in simulation is illustrated. Furthermore, simulated analyses show that high performance non-inverted wavelength conversion based on NPR can be achieved by using a red-shifted filtering scheme.     

320 Gbit/s wavelength conversion using four-wave mixing in quantum-dot semiconductor optical amplifiers

In this study, we demonstrate error-free all-optical wavelength conversion of ultrahigh-speed intensity modulated signals by means of four-wave mixing in a quantum-dot semiconductor optical amplifier. Error-free performance at a bit rate of 320 Gbit/s is measured for the extracted 40 Gbit/s tributaries with a 3.4 dB average power penalty to the original signal.     

Double-Doppler wavelength conversion of infrared optical pulses by moving grating of refractive index in semiconductors

Optical and Quantum Electronics - A time-domain model of an excited semiconductor medium as a moving Bragg grating was used to investigate a double-Doppler wavelength conversion of an infrared...     

A method of segment protection based on p-cycle for dynamic multicast with limited-range wavelength converter in WDM network

In the optical multicast network, node and link failures have very important influence on the network survivability which may lead to multiple destinations cannot receive data. Based on the wavelength layered-graph method, a method of efficiency-score based on heuristic algorithm of pre-configured cycle (p-Cycle) based-segment protection (ESHS) for dynamic multicast with limited-range wavelength conversion was presented in this paper. By finding the multicast tree segment protection, the total available p-Cycles are constructed for the multicast. Then we calculate each p-Cycle efficiency-score, the highest efficient-score p-Cycle is selected as the multicast route protection p-Cycle. The simulation results show that the ESHS can get higher performance than the existing ESHT algorithm, in terms of multicast request blocking probability and wavelength utilization.     

Blocking in wavelength-routed all-optical WDM network with wavelength conversion

The blocking probability in wavelength-routed all optical networks is very important measure of performance of the network, which can be affected by many factors such as network topology, traffic load, number of links, algorithms employed and whether wavelength conversion is available or not. In this paper, we have proposed a mathematical model to reduce the blocking probability of the WDM optical network for wavelength-convertible networks. The model can be used to evaluate the blocking performance of any network topology also it can be useful to improve its blocking performance of the given network topology. The blocking probability variation of the network for a particular load (per link) has been studied based on the load variation and total number of wavelengths used in the network. This model gives good results for high load (per link).     

Simultaneous optical wavelength interchange with a two-dimensional second-order nonlinear photonic crystal

We present a theoretical analysis for simultaneous optical wavelength interchange and isolation of a pair of collinear input optical signals by use of two concurrent difference-frequency-generation processes in a two-dimensional second-order nonlinear photonic crystal. We have derived a set of relations, including a general nonlinear Bragg condition, that we use to determine the parameters of the nonlinear lattice, given the input wavelengths and desired exit angles of the wavelength-interchanged outputs.