大面積方形面射型雷射偏振動態之研究

Abstract

邊長為55微米的大面積方形面射型雷射，近場圖騰可觀察到角落有亮點產生，這些亮點是由電流區域集中效應(current crowding effect)所造成的，屬於縱向的低發散模態，本文針對這些低發散模態做一系列的研究，首先探討亮點的基本特性。接著研究低發散模態的偏振動態行為，發現互相垂直正交的偏振模態彼此競爭，會導致隨時間震盪之波形有趣的變化，分析隨時間震盪之波形強度的駐留時間(dwell time)與傅立葉轉換(Fourier transform)結果。最後，與高發散模態的特性做比較。

For broad-area square VCSELs with aperture size of 55 μm, light spots are usually generated in the near-field patterns. These light spots are caused by the current crowding effect and propagate with very low divergent angle. In this paper, we experimentally investigate the characters of these low divergent modes. First, the basic physical properties of light spots are presented. Then we study the polarization dynamics of the low divergent modes. It is found that the competition between polarized modes will lead to interesting features in the time trace oscillations. Moreover, we analyze the time traces of polarization-resolved intensities, including the results of dwell time and Fourier transform. Finally, we present the properties of the high divergent modes.