基于氧化限制型内腔接触垂直腔面发射激光器(VCSEL)结构设计,研究了VCSEL的多横模分布及其模式波长分裂特性与氧化孔径尺寸、形状的关系.在实验基础上,通过建立有效折射率模型,并利用标量亥姆霍兹方程的迭代算法理论,分别对椭圆形氧化孔径和圆形氧化孔径VCSEL的横向模式特性进行模拟研究,计算得到不同形状孔径的多横模光场分布情况,同时测量得到高阶横模多频输出光谱.研究发现,椭圆氧化孔形状不仅影响横模分布特性,还会导致每个模式的波长产生分裂,分裂值可达0.037nm.同时,随着氧化孔径的增大,波长分裂影响会逐渐减小,直至趋近于圆形氧化孔径的分布特性.研究结果为进一步实现氧化限制型VCSEL的多横模锁定提供了有益参考和借鉴.
We study the multi-transverse mode distributions and the wavelength splittings with different designed oxide aper- tures of the oxide-confined VCSEL. By developing the effective index model and BPM algorithm theory, the charac- teristics of transverse optical field distribution are calculated with circular aperture and ellipsoid aperture, which are compared with our experimental results of multi-wavelength spectra of high-order transverse modes. The results show that the orthogonality of the different crystal orientation modes will be broken by the oxidation-induced ellipsoid aper- ture, and the maximum wavelength spitting of the degenerated high-order mode is 0.037 nrn, which can be reduced as the diameter of aperture increases. The results in this paper will provide a useful reference for multi-transverse mode locking of oxide-confined VCSELs.