"Studies on Tuning of Photonic Crystal Characteristics after Fabrication"

(1)电子束辐照二维柱状结构的位置控制及其激光作用通过干法刻蚀GaAs/A1GaAs多层结构制备具有二维柱状结构的光子晶体。通过电子束在扫描电子显微镜下的照射，观察到规则排列的晶格发生了局部变形和团簇。从库仑引力和排斥力的平衡角度分析了这一现象。结果表明，库仑力足以使直径为0.3 μm、长度为1μm的矿柱发生永久变形。利用钛蓝宝石激光器作为激发源，研究了上述二维光子晶体的激光特性。根据输出光功率与激发功率的关系，确定晶体的激发阈值为100mW。激光波长位于计算光子带隙的高能边缘，在这里砷化镓的光学增益带与光子带隙交叉。(2)光子晶体与半导体复合结构的制备与评价上述具有调谐机制的光子晶体结构有一个缺点，即虽然基础材料是半导体，但干蚀刻损伤会导致光学增益较差。为了克服这一问题，将介电光子晶体与半导体多层结构相结合。即在表面有二维波纹的半导体MOW结构上生长SiO_2/Si三维光子晶体。过度生长光子晶体的存在影响了光致发光在MQW波导中的传播，并在MOW光学增益和光子晶体周期特性的相互作用下产生了新的发光峰。除半导体衬底外，还成功地应用了铝金属阳极氧化制备的氧化铝霍尔阵列。(3)通过光子晶体光纤产生超连续光我们关注了光子晶体光纤包层中非常小的芯，这些芯是无意产生的，称为伪芯。采用特殊设计的耦合光学器件，使脉冲宽度小于1ps的钛蓝宝石脉冲激光击中特定的伪核成为可能。在450nm ~ 1400nm范围内获得了超连续光谱。由于伪核的尺寸很小，即使是亚毫米长的光纤也能产生超连续光，这是我们所知道的产生超连续光的最短长度。用硅光刻法制备了35μm长的sio2空气悬浮线，初步观察了超连续光。少

(1)Position control of 2D pillar structure by electron beam irradiation and their lasing actionPhotonic crystal with 2D pillar structure is fabricated by dry etching of GaAs/A1GaAs multi-layered structure. By irradiation of electron beam in the SEM apparatus, it observed that regularly arranged lattice was deformed and bunched locally. This phenomenon is analyzed in terms of the balance of Coulomb attractive and repulsive forces. It was found that the Coulomb force is enough strong to give permanent deformation to the pillar with the dimensions of 0.3 μm diameter and 1μm long.Lasing characteristics were investigated on the 2D photonic crystal mentioned above using Ti-Sapphire laser as an excitation source. It was confirmed that the crystal lased with the excitation threshold of 100mW based on the dependence of output light power on excitation power. The lasing wavelength was at the higher energy edge of the calculated photonic band gap, where the optical gain band of GaAs and the photo … More nic band gap cross over.(2)Fabrication and evaluation of the combined structure photonic crystal and semiconductorAbove-mentioned photonic crystal structure with tuning mechanism has a weak point that dry etched damage results in poor optical gain although basic material is semiconductor. To overcome this problem, dielectric photonic crystal was combined with semiconductor multiplayer structure. That is, SiO_2/Si 3D photonic crystal was grown on semiconductor MOW structure with 2D corrugation on their surface. Photoluminescence propagating through MQW waveguide was affected by the presence of overgrown photonic crystal and showed new luminescence peak resulted from interaction of MOW optical gain and periodical feature of the photonic crystal. In addition to the semiconductor substrate, aluminum oxide hall array fabricated by anodic oxidization of aluminum metal was successfully used.(3)Supercontinuum light generation through photonic crystal fiberWe have paid attention to the very small cores in the cladding of photonic crystal fiber, which are unintentionally generated and so-called pseudo core. Using specially designed coupling optics it became possible to hit the specific pseudo core by Ti-Sapphire pulse laser with pulse width less than 1ps. The supercontinuum light raged from 450nm to 1400nm was obtained. Since the size of the pseudo core is so small even sub-mm-long-fiber is able to produce the supercontinuum light, which is, to our knowledge, the shortest length of supercontinuum light generation. It was preliminarily observed the supercontinuum light with 35μm-long-SiO2 air suspended wire fabricated by Si photolithography. Less