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1.
基于自旋反向模型(SFM),数值研究了基于光反馈的单向耦合注入垂直腔表面发射激光器的矢量混沌同步特性,研究结果表明:当外部光反馈时间等于光从发射系统到接收系统传输时间时, x偏振模和y偏振模都能接收最好的完全混沌同步质量.若外部光反馈时间不等于传输时间且注入电流接近阈值电流时,占主导的y偏振模能暂时实现较好的完全混沌同步质量.相比较而言,占主导地位的x偏振模至始至终获得很差的同步质量,另外,当系统输出为混合偏振模时,混合偏振模中的每一个线性偏振模获得很差完全同步质量.然而,当注入电流远大于阈值电流时,系统输出仅为y偏振模,这时y偏振模能稳定地实现最好的完全混沌同步质量.最后,当接收激光器受到线性偏振模的强注入时,每一个注入线性偏振模能与接收激光器输出的对应的线性偏振模实现很好的注入锁定同步.然而,每一个占主导的线性偏振模比另一被抑制的线性偏振模获得更差注入锁定同步质量、如果有相等的能量的两个线性偏振模同时存在,这两个线性偏振模获得差不多一致的注入锁定混同步质量, 换句话说,能量较少的线性偏振能获得较高的注入锁定同步质量.
关键词:
线性偏振态
垂直腔表面发射激光器
完全矢量混沌同步
强注入锁定矢量混沌同步 相似文献
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基于扩展的自旋反转模型,对光反馈诱发下长波长垂直腔面发射激光器中的低功耗偏振开关进行了理论研究.研究表明:长波长垂直腔面发射激光器在自由运行下未能获得的偏振开关现象,可以通过引入中等强度的偏振旋转光反馈来实现.对比强弱两种不同的线性色散效应,发现了一些有趣的现象:弱线性色散条件下更易于在低注入电流下获得偏振开关,并且产生偏振开关所需的反馈强度具有更大的调控范围;强色散效应中未能始终获得偏振开关,会出现两模共存区,并且偏振开关出现的注入电流值较高.同时,观察到的偏振模跳变和多偏振开关现象类似于短波长垂直腔面发射激光器,因而证实这两类激光器在偏振开关的本质规律上是相似的.此外,还对长波长垂直腔面发射激光器不易在低注入电流下获得偏振开关的原因进行了分析,并给出了合理的解释. 相似文献
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基于扩展的自旋反转模型, 对光电负反馈下垂直腔表面发射激光器的偏振开关特性进行了数值仿真和理论分析. 研究结果表明: 对于不同的自旋反转率, 反馈强度和延迟时间对激光器偏振开关特性产生较大影响.在慢自旋反转率下运行时, 随着反馈强度的增加, 开关点电流呈线性增加, 导致X偏振模被压缩, 这与报道的基于各向同性光反馈的情景相反, 产生这一现象的原因是由于光电负反馈提高了X偏振模的阈值; 延迟时间对开关点电流的影响随反馈强度的变化而不同.在快自旋反转率下运行时, 反馈强度对开关点电流的影响与慢自旋反转率时的情形不同, 开关点电流经历先增加后减小的过程, 开关点电流受反馈强度的影响更加敏感; 而延迟时间的影响规律和慢自旋反转率时相似. 此外, 还发现自发辐射噪声对激光器偏振开关特性有较大影响.
关键词:
垂直腔表面发射激光器
偏振开关
光电负反馈
自发辐射噪声 相似文献
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提出将正交互耦1550 nm垂直腔面发射激光器(1550 nm-VCSEL)在优化条件下输出的多路平均功率可比拟、延时特征(TDS)得到有效抑制的混沌信号作为混沌熵源,经8位模数转换器(ADC)量化和最低有效位(m-LSB)后续处理获取多路物理随机数的方案,并研究了系统参量对最终获取的比特序列随机性的影响.首先,基于VCSEL的自旋反转模型分析耦合强度和频率失谐对两个正交互耦合1550 nm-VCSEL输出动力学的影响,初步确定利用该系统产生四路平均功率可比拟、TDS得到抑制的混沌信号所需的耦合强度和频率失谐优化范围;在此基础上,选择一个耦合强度值,利用处于优化范围内的不同频率失谐下获取的四路混沌信号作为熵源,经8位ADC量化和m-LSB后续处理得到最终的比特序列;最后,采用NIST Special Publication800-22统计测试套件对获取的最终比特序列的随机性能进行测试,确定了同时获取四路高质量随机数所需的参数范围. 相似文献
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Based on the SFM model [M. San Miguel, Q. Feng, J.V. Moloney, Phys. Rev. A. 52 (1995) 1728.], complete chaotic synchronization characteristics of linear-polarization (LP) Mode of the vertical-cavity surface-emitting semiconductor lasers (VCSELs) with isotropic optical feedback are numerically investigated. When the propagation time τc of light from the transmitter to the receiver equals to the external cavity round-trip time τ, and the central frequency of the T_VCSEL matches that of the R_VCSEL, in large scale region of the feedback coefficient and the injection current where the x-polarization mode as well as the y-polarization mode obtains high synchronization quality at the same time. However, in the central frequency mismatch regions where the x- and y-polarization mode can obtain inferior synchronization quality at same time. But for τc ≠ τ, each LP mode of the mixed polarization modes achieved inferior synchronization quality at the same time. Besides, with big enough injection current, the output of the system with the same central frequency in two lasers is entirely governed by the y-polarization mode when the feedback coefficient and Δτ(=τc − τ) fixed at a certain value. So the system can realize steadily good synchronization of the completely dominant y-polarization mode. But the synchronization quality of the completely dominated y-polarization mode can be deteriorated by increasing absolute frequency detuning value. Besides, in positive frequency mismatch regions where the influence of the same frequency detuning value on the synchronization quality of the entirely governed y-polarization mode becomes smaller than in negative frequency detuning regions. At last, when τ is given and the central frequency of the T_VCSEL matches that of the R_VCSEL, the influence of the τc is not a simple time-shift in the time-evolution of the receiver VCSEL, which has serious influence on the complete synchronization quality of each LP mode. 相似文献
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利用两个电流偏置在不同值的半导体激光器(SL)构建一个延时互耦系统,实验研究了两个SL的非对称偏置电流和频率失谐Δf(=f1-f2,f1,f2分别对应SL1和SL2的自由振荡频率)对系统混沌同步性能的影响.研究结果表明:对于两个振荡频率一致的SL,当两个SL的偏置电流差异较大时系统能实现较好的混沌同步;通过调节两个SL的温度,使两个SL的振荡频率失谐,对于SL1电流远大于SL2电流的情形,正频率失谐
关键词:
半导体激光器
非对称电流偏置
互耦
混沌同步 相似文献
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通过在互耦合垂直腔面发射激光器(VCSELs)系统中增加外光注入, 建立了一种基于偏振可调光反馈VCSEL驱动互耦合VCSELs混沌系统模型, 分析了增加外光驱动对互耦合激光器随机特性的影响. 以不可预测度作为随机特性的评价指标, 采用信息论中的排列熵作为相应量化工具, 对系统输出混沌信号的不可预测性进行定量分析.数值研究了光强度、时延、偏振旋转角度以及驱动激光器与耦合激光器间的频率失谐对输出信号随机特性的影响.结果表明: 外光注入能够增大互耦合VCSELs输出混沌信号的排列熵, 即外光注入能够有效提高耦合系统的随机特性; 驱动激光器可调偏振片偏转角度调节到45° 附近, 注入强度适中, 满足耦合强度大于驱动激光器自反馈强度条件, 系统输出信号的排列熵较大; 在耦合时延与驱动激光器反馈时延不相等的同时, 增加驱动激光器与耦合激光器频率失谐, 外光注入互耦合VCSELs的随机特性能够得到进一步提高. 相似文献
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通过在互耦合外腔半导体激光器之间增加中继激光器,建立了一种链式互耦合半导体激光器混沌同步系统模型.理论分析了系统的实时混沌同步条件,数值研究了注入电流、互耦合条件、反馈条件等对系统实时混沌同步品质的影响,揭示了同步质量在反馈强度和互耦合强度二维参数空间的分布规律.结果表明:注入电流较大时,满足互耦合强度和反馈强度相同,互耦合延时和反馈延时相等,系统中所有激光器之间可同时实现稳定高品质实时混沌同步;中心激光器和边激光器之间的稳定实时混沌同步分布在在互耦合强度和反馈强度较小的区域以及互耦合强度和反馈强度相近的区域;边激光器之间由于同时接收到中心激光器实施的相同注入,能够较容易的实现稳定高品质的实时混沌同步.该系统可进一步扩展成为实现远距离的双向实时混沌同步或阵列激光器系统的实时混沌同步. 相似文献
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依据导电介质的稳态电场理论建立了一种对增益导波型垂直腔半导体激光器注入电流矢量分析的三维解析模型. 计算研究了电流密度空间分布及其与顶面电注入环参量之间的相互关联性. 结果显示在两极之间存在一个载流子径向分布中心极大的区域. 由于激光功率与注入电流之间存在线性关系,因此,要使器件能够获得基模或中心均匀的光强输出以及尽可能低的阈值,应使激光有源层与载流子均匀分布的临界层重合. 计算结果对顶发射与底发射结构以及不同环参数下的载流子分布情况及对近场模式形成的影响进行了分析和讨论.
关键词:
垂直谐振腔激光器
注入电流
激光模式 相似文献
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K. Panajotov M. Sciamanna I. Gatare M. Arizaleta Arteaga H. Thienpont 《Opto-Electronics Review》2008,16(4):337-346
In this paper we summarize the recent results on nonlinear dynamics of vertical-cavity surface-emitting lasers (VCSELs) which
are bearing the fingerprints of the particular polarization properties of VCSELs. Due to the surface emission and cylindrical
symmetry, VCSELs lack strong polarization anisotropy and may undergo polarization switching and polarization mode-hopping.
This provides new specificities to the rich nonlinear dynamics induced in VCSELs by an external perturbation. We unveil both
experimentally and theoretically these new specificities for the case of optical feedback, optical injection, and unidirectional
synchronization between VCSELs. 相似文献
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Two vertical-cavity surface-emitting lasers(VCSELs) are mutually coupled through a partially transparent mirror (PTM) placed in the pathway. The PTM plays the role of external mirror,which controls the feedback strength and coupling strength.We numerically simulate this system by establishing a visible SIMULINK model.The results demonstrate that the anticipation synchronization is achieved and it can tolerate some extent frequency detuning.Moreover,the system shows similar chaos-pass filtering effect on unidirectionally coupled system even both VCSELs are modulated.This system allows simultaneously bidirectional secure message transmission on public channels. 相似文献
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垂直腔面发射激光器(VCSEL)中的载流子聚集效应使注入到有源区的工作电流只是通过边缘环形区域很窄的通道,激光功率密度分布不均匀;尤其当器件尺寸较大时,激射光斑呈现环状,环中间光强很弱.这是研制电抽运高功率大尺寸VCSEL尤为突出的技术难题.采用新型结构成功研制出808 nm波段高功率大孔径VCSEL,在注入电流为1A时,室温下连续输出功率达0.3 W.
关键词:
半导体激光器
垂直腔面发射激光器
高功率
大孔径 相似文献
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A multi-hole vertical-cavity surface-emitting laser (VCSEL) operating in stable single mode with a low threshold current was produced by introducing multi-leaf scallop holes on the top distributed Bragg-reflector of an oxidation-confined 850 nm VCSEL. The single-mode output power of 2.6 mW, threshold current of 0.6 mA, full width of half maximum lasing spectrum of less than 0.1 nm, side mode suppression ratio of 28.4 dB, and far-field divergence angle of about 10° are obtained. The effects of different hole depths on the optical characteristics are simulated and analysed, including far-field divergence, spectrum and lateral cavity mode. The single-mode performance of this multi-hole device is attributed to the large radiation loss from the inter-hole spacing and the scattering loss at the bottom of the holes, particularly for higher order modes. 相似文献
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We report the study on a short wavelength-tunable vertical-cavity
surface-emitting laser utilizing a monolithically integrated bridge tuning
microelectromechanical system. A deformable-bridge top mirror
suspended above an active region is utilized. Applied bridge-substrate bias
produces an electrostatic force which reduces the spacing of
air-gap and tunes the resonant wavelength toward a shorter wavelength
(blue-shift). Good laser characteristics are obtained: such as continuous tuning
ranges over 11 nm near 940 nm for 0--9 V tuning bias, the peak output power
near 1 mW and the full-width-half-maximum limited to approximately
3.2--6.8 nm. A detailed simulation of the micromechanical and optical
characteristics of these devices is performed, and the ratio of
bridge displacement to wavelength shift has been found to be 3:1. 相似文献
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