基于耦合光栅微腔的全偏振模式锁定可调谐垂直腔面发射激光器及阵列集成研究

Nowadays, the optical Internet networking based on the vertical-cavity surface-emitting lasers (VCSELs) has been widely used in the warehouse scale data centers and high-performance supercomputers. As the light sources, the traditional VCSELs with low integration, limited modulation rate, unstable polarization, and single length become more and more difficult to satisfy the needs for high-speed parallel, small size, high integration, low-cost manufacturability, and high-bandwidth applications in the coming of large data era. VCSEL arrays with multi-wavelength have become a vital candidate for replacing the traditional light source. However, there are several limitations of multi-wavelength VCSELs such as narrow bandwidth range, poor thermal wavelength shift, and lack of methods to adjust polarization mode and wavelength mode independently. In the project, high speed and superior performance VCSEL arrays has been designed for wide modulation bandwidth, whole polarization, and mode locking. The key concept of our new device is the manipulation of the temperature dependence of wavelength using the electrostatic force actuation of the micro-machined mirror to reduce the thermal wavelength drift. At the same time, sub-wavelength grating was embedded into the active region to be the quantum phase diffractive optical elements with near-field enhancement, which effectively separate and control the polarization mode of TE and TM in aspect of polarization gain anisotropy. The physical mechanism of interaction between the internal cavity coupling and the dynamic tuning behavior of the polarization wavelength is also studied. Furthermore, the new methods and the technology of novel tunable VCSEL devices are developed.

基于垂直腔面发射激光器（VCSEL）的光互联网络现已广泛应用于超规模数据存储中心和高性能计算机中。随着大数据时代的来临，低集成度、低调制速度、偏振不稳定和单一波长的传统VCSEL光源将越来越不能满足大数据信息系统对高速并行、小尺寸、高集成、低成本和高带宽的要求。采用多波长阵列集成的VCSEL将成为取代传统光源的重要选择。但目前多波长VCSEL阵列工作频带窄、波长温漂严重，偏振和波长模式不能独立调节。本课题以高速高性能可调谐VCSEL阵列为研究对象，以宽调谐频带、全偏振、模式锁定为主要目标，以合成技术为主线，采用耦合光栅微腔近场增强相位控制技术，以微机械调谐为主和动态反馈补偿VCSEL阵列波长温漂为辅展开研究。从理论和实验上阐明新型可调谐VCSEL阵列的波长偏振稳定调谐机理，深入研究、表征微结构与偏振控制和波长动态调谐行为间的相互作用物理机制，探索出基于多微腔光子近场耦合的新物理效应和理论。

随着信息化时代科学技术的高速发展，高性能垂直腔面发射激光器已成为面向高速高密度集成的光互联核心器件。其具有自身独特的圆形对称光斑、小体积、低功耗和高相干度阵列集成等特点，并且与传统边发射激光器相比，无需解理封装可直接在片测试分析，大大降低了制造成本。因此，具有重要的商业和军事价值并被大量生产，被广泛地应用到光交换、光互连、光计算和生物医疗等领域中。因此，宽范围可调谐VCSEL偏振控制技术的研究成为高性能半导体光源领域中的研究热点和难点。为解决这些难题，我们基于微纳光栅结构，发展可调谐VCSEL多光腔耦合理论，提出耦合光栅微腔激光器结构；以及在此基础上实现全偏振控制的可调谐VCSEL技术，重点开展了可调谐窄线宽VCSEL激光器的研究工作，并基于共振耦合微腔理论，动态调节补偿相位匹配，在光波偏振控制过程中，利用光栅强衍射效应对正交偏振态进行调制的方法，设计并优化内腔亚波长光栅波长可调谐VCSEL，理论分析了亚波长光栅参数对TE/TM偏振波长调谐范围的影响关系，并获得最大TE/TM偏振调谐范围的光栅参数，从而得出TE/TM单偏振最大波长调谐范围，在TE偏振稳定下实现18nm波长调谐范围，而对于TM偏振可实现21nm的波长调谐范围。并在实验基础上，对可调谐VCSEL调谐系统进行了分析，开展调谐过程中调谐范围、输出功率等变化特性的理论研究，成功设计制备出了新型亚波长可调谐VCSEL，实现波长调谐范围达到11nm，调谐电压为3V。成功制备了液晶可调谐VCSEL阵列激光器，并从VCSEL阵列的特征温度、单管阈值电流温漂率、斜率效率、热阻和阵列温度分布多个参数分析激光器阵列热稳定的影响。1×1、2×2、3×3三种阵列的特征温度最大提高了54%，斜率效率最高可达0.717，出光孔与注入电极外侧的温差由原来的2.6℃下降至0.5℃以下，阵列温度分布更加均匀。相关成果在《Advanced Materials》，《Optics and Laser Technology》、《Chinese Physics》、《Chinese Physics Letters》、《物理学报》等国内外学术期刊发表论文14篇,申请国家发明专利9项。为实现高光束质量的单偏振波长可控VCSEL激光器阵列打下了良好的理论和实验基础。