Białek Ewelina, Włodarski Maksymilian, Norek Małgorzata
Institute of Materials Science and Engineering, Faculty of Advanced Technologies and Chemistry, Military University of Technology, Str. gen Sylwestra Kaliskiego 2, 00-908 Warsaw, Poland.
Institute of Optoelectronics, Military University of Technology, Str. gen. Sylwestra Kaliskiego 2, 00-908 Warsaw, Poland.
Nanotechnology. 2023 Jan 13;34(12). doi: 10.1088/1361-6528/aca546.
The mid-infrared region (MIR) is crucial for many applications in security and industry, in chemical and biomolecular sensing, since it contains strong characteristic vibrational transitions of many important molecules and gases (e.g. CO, CH, CO). Despite its great potential, the optical systems operating in this spectral domain are still under development. The situation is caused mainly by the lack of inexpensive and adequate optical materials which show no absorption in the MIR. In this work, we present an easy and affordable way to develop 1D photonic crystals (PCs) based on porous anodic alumina for MIR region. The porous PCs were produced by the pulse anodization of aluminum using charge-controlled mode. The first order photonic stopbands () were located within ca. 3.5-6.5m. Annealing of the material at 1100 °C for an hour has allowed to recover the wavelength range from around 5.8 to 7.5m owing to the decomposition of the absorption centers (oxalate anions) present in the anodic oxide framework while maintaining the PC structural stability. The spectral position and the shape of the resonances were regulated by the charge passing under high () and low () voltage pulses, porosity of the correspondingandsegments, and dura tion of the process (). The thickness of theandlayers was proportional to the charge passing under respective pulses, with the proportionality coefficient increasing with the applied voltage. Despite the constant charge (2500 mC cm) applied during the anodization, the thickness of anodic alumina (d) increased with applied voltage (10-60 V) and anodizing temperature (5 °C-30 °C). This behavior was ascribed to the different kinetics of the anodic alumina formation prompted by the variable electrochemical conditions. The photonic material can be used in portable nondispersive gas sensors as an enhancement layer operating up to around 9m.
中红外区域（MIR）对于安全和工业、化学及生物分子传感等诸多应用至关重要，因为它包含许多重要分子和气体（如CO、CH、CO）的强特征振动跃迁。尽管具有巨大潜力，但在此光谱域运行的光学系统仍在开发中。这种情况主要是由于缺乏在中红外区域无吸收的廉价且合适的光学材料。在这项工作中，我们提出了一种简单且经济实惠的方法来开发基于多孔阳极氧化铝的用于中红外区域的一维光子晶体（PCs）。多孔PCs是通过采用电荷控制模式对铝进行脉冲阳极氧化制备的。一阶光子禁带位于约3.5 - 6.5μm范围内。在1100℃下对材料进行一小时退火，由于阳极氧化物框架中存在的吸收中心（草酸根阴离子）分解，使得波长范围从约5.8μm恢复到7.5μm左右，同时保持了PC结构的稳定性。共振的光谱位置和形状由高（）和低（）电压脉冲下通过的电荷、相应和段的孔隙率以及过程的持续时间（）调节。和层的厚度与各自脉冲下通过的电荷成正比，比例系数随施加电压增加。尽管在阳极氧化过程中施加的电荷恒定（2500 mC/cm²），但阳极氧化铝的厚度（d）随施加电压（10 - 60 V）和阳极氧化温度（5℃ - 30℃）增加。这种行为归因于可变电化学条件促使的阳极氧化铝形成的不同动力学。这种光子材料可用于便携式非色散气体传感器，作为工作至约9μm的增强层。
