双偏振光注入下1550 nm VCSEL的偏振开关特性研究

发布时间：2018-07-04 17:16

本文选题：1550 + nm垂直腔面发射激光器(1550　；参考：《西南大学》2017年硕士论文

【摘要】：垂直腔面发射激光器(VCSELs)作为新型的光电器件,因具有低阈值电流、单纵模输出、较大的调制带宽、发散角小、与光纤的耦合性好、易于实现二维阵列等独特的优势而备受关注。特别地,由于VCSELs的特殊结构和有源区增益介质的二向色性和双折射效应,自由运行的VCSELs可输出两个正交的偏振分量。当偏置电流、温度等条件变化或引入光反馈、光注入等外部扰动时,两偏振分量之间可发生能量的相互转换,即偏振开关(polarization switching,PS)。其中,光注入是研究VCSELs PS特性的常用方式,目前的相关研究主要集中在连续光注入方式,而对于脉冲光注入,尤其是双偏振脉冲光注入下VCSELs PS特性的研究相对缺乏。特别地,PS时间涉及信息处理速率及系统的运行稳定性,因此,研究VCSELs的PS特性对未来基于VCSELs的全光信息处理系统的发展具有重要的意义。本文基于自旋反转模型(SFM),理论研究了1550nm VCSEL在双偏振脉冲光注入(DPPI)下输出两个偏振分量的PS特性。研究结果表明,与1550nm VCSEL同时受到一个正交偏振脉冲光和一个平行偏振连续光注入(脉冲正交偏振双光注入(DIPOP))的情况相比,在合适的参数条件下,DPPI方式能使PS时间更短,且其消光比更大。对于50 MHz的脉冲注入信号,在DPPI方式下,1550nm VCSEL输出的PS特性会受到两个注入脉冲的切换时间差值Δt的影响,每一个偏置电流对应一个最佳的Δt值,且这个值随偏置电流增加而呈现逐渐减小的趋势。对于固定的偏置电流、最佳Δt值及频率失谐,X(Y)偏振输出的开关时间主要取决于偏振脉冲注入强度Einj,x(Einj,y),且X(Y)偏振输出的开关时间随Einj,x(Einj,y)的增加而变短;对于固定的注入强度,负频率失谐有利于减小X和Y偏振输出的开关时间。因此,通过改变注入强度以及频率失谐,两个偏振输出的PS开关时间都能够得到有效调控。此外,我们也给出了1550 nm VCSEL在受到两个2.5 Gb/s NRZ信号注入时的系统响应。
[Abstract]:As a new type of optoelectronic device, Vertical cavity Surface emitting Laser (VCSELs) has attracted much attention because of its advantages such as low threshold current, single longitudinal mode output, large modulation bandwidth, small divergence angle, good coupling with fiber and easy to realize two-dimensional array. In particular, due to the special structure of VCSELs and the dichroism and birefringence of the gain medium in the active region, the free-running VCSELs can output two orthogonal polarization components. When the bias current, temperature and other conditions are changed or the external disturbances such as optical feedback and optical injection are introduced, the energy conversion between the two polarization components can occur, that is, the polarization switching switch (PS). Among them, optical injection is a common way to study the characteristics of VCSELs PS. At present, the related research is mainly focused on the continuous optical injection mode, but the study on the characteristics of pulsed light injection, especially under the dual polarization pulsed light injection, is relatively scarce. In particular, PS time is related to the information processing rate and the stability of the system. Therefore, it is of great significance to study the PS characteristics of VCSELs for the development of all-optical information processing systems based on VCSELs in the future. Based on the spin inversion model (SFM), the PS characteristics of 1550nm VCSEL with two polarization components output under double polarization pulse injection (DPPI) are studied theoretically. The results show that the PS time is shorter under the suitable parameters than that when 1550nm is simultaneously injected by an orthogonal polarized pulse and a parallel polarized continuous optical injection (DIPOP). And its extinction ratio is larger. For 50 MHz pulse injection signal, the PS characteristics of 1550nm VCSEL output in DPPI mode are affected by the switching time difference 螖 t of two injection pulses, and each bias current corresponds to an optimum 螖 t value. And the value decreases gradually with the increase of bias current. For a fixed bias current, the best 螖 t value and the switching time of polarization output of frequency detuning X (Y) mainly depend on the polarization pulse injection intensity Einjx (Einjy), and the switching time of X (Y) polarization output becomes shorter with the increase of EinjX (Einjy). The negative frequency detuning can reduce the switching time of X and Y polarization output. Therefore, by changing the injection intensity and frequency detuning, the PS switching time of both polarization outputs can be effectively regulated. In addition, we also give the system response of 1550 nm VCSEL when injected by two 2.5 GB / s NRZ signals.
【学位授予单位】：西南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN248

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