Saini Sudhir Kumar, Nair Rajesh V
Laboratory for Nano-Scale Optics and Meta-Materials (LaNOM), Department of Physics, Indian Institute of Technology Ropar, Punjab 140001, India.
Chem Commun (Camb). 2022 Feb 1;58(10):1481-1494. doi: 10.1039/d1cc05787a.
The advent of photonic crystals has made possible the idea of controlling flows of light, which has revolutionized photonics-based technology. Photonic crystals are constructed based on periodic refractive index variations in one-, two-, or three-spatial dimensions on the optical-wavelength scale. Photonic crystals show inherent photonic stop gaps or band gaps depending upon the crystal symmetry and refractive index contrast. Showing ease of fabrication, polymer-based self-assembled photonic crystals with stop gaps have been widely explored. We discuss angle- and polarization-dependent stop gap creation and splitting at higher angles of incidence. The observed stop gaps in self-assembled photonic crystals often deviate from theoretical predictions due to experimental constraints, such as finite size and fabrication disorders associated with samples. We perform micro-reflectivity experiments on a single domain, showing minimal disorder, with nearly 100% reflectivity, which is in agreement with theory. We obtain more than 75% emission intensity suppression and a 30% increase in the emission lifetime at the stop gap using micro-emission experiments in a single domain. This enables us to study the role of finite-size effects in photonic crystals in modifying the emission properties. We observe the linear scaling of the emission intensity suppression and the emission rate with the finite size of the crystal. Our single-domain experimental studies reveal that the use of low index-contrast self-assembled photonic crystals is a potential platform for strategically modifying light transport and emission properties.
光子晶体的出现使控制光流的想法成为可能，这彻底改变了基于光子学的技术。光子晶体是基于光学波长尺度上一维、二维或三维空间中周期性的折射率变化构建而成的。根据晶体对称性和折射率对比度，光子晶体呈现出固有的光子禁带或带隙。由于易于制造，具有禁带的聚合物基自组装光子晶体已得到广泛研究。我们讨论了在较高入射角下与角度和偏振相关的禁带产生和分裂。由于实验限制，如与样品相关的有限尺寸和制造缺陷，自组装光子晶体中观察到的禁带往往偏离理论预测。我们在一个单畴上进行了微反射率实验，显示出最小的无序度，反射率接近100%，这与理论相符。通过在一个单畴上进行微发射实验，我们在禁带处获得了超过75%的发射强度抑制和30%的发射寿命增加。这使我们能够研究光子晶体中有限尺寸效应在改变发射特性方面的作用。我们观察到发射强度抑制和发射率与晶体的有限尺寸呈线性比例关系。我们的单畴实验研究表明，使用低折射率对比度的自组装光子晶体是战略性地改变光传输和发射特性的潜在平台。
