The ongoing quest for higher data storage density has led to a plethora of innovations in the field of optical data storage. This review paper provides a comprehensive overview of recent advancements in next-generation optical data storage, offering insights into various technological roadmaps. We pay particular attention to multidimensional and superresolution approaches, each of which uniquely addresses the challenge of dense storage. The multidimensional approach exploits multiple parameters of light, allowing for the storage of multiple bits of information within a single voxel while still adhering to diffraction limitation. Alternatively, superresolution approaches leverage the photoexcitation and photoinhibition properties of materials to create diffraction-unlimited data voxels. We conclude by summarizing the immense opportunities these approaches present, while also outlining the formidable challenges they face in the transition to industrial applications.

分子的多形态(多晶型)是指化学组成相同但存在不止一种晶体形式的物质。 这些多形态广泛存在于自然界中, 其中药物的多形态尤其普遍。 这些药物多形态虽然具有相同的化学分子组成, 但其理化性质却存在差异, 最终会导致药物作用功能的不同。 近年来, 随着太赫兹(THz)辐射源的产生方式成为一种常规技术后, 太赫兹时域光谱技术(THz-TDS)的应用领域逐渐被拓宽。 因为THz波不仅与分子内作用模式有关, 更与氢键和范德华力等弱相互作用模式密切相关; THz辐射可以诱发低频键振动、 晶体声子振动、 氢键拉伸和扭转振动, 许多有机分子的集体振动模式处于该波段, 尤其是药物分子。 基于此, 采用THz-TDS技术, 研究了马来酰肼药物分子两种多形态(MH2和MH3)在0.25~2.25 THz波段的THz吸收谱。 通过实验测试, 发现MH2和MH3的THz特征吸收峰完全不同, MH2获取到了三个特征吸收峰, 分别位于0.34, 1.41和1.76 THz; MH3晶型获取两个特征吸收峰, 分别位于0.75和1.86 THz处; 此结果表明马来酰肼多形态可以通过其THz特征吸收峰进行辨别表征。 接着, 为了对THz实验吸收峰进行解析, 采用固态密度泛函理论(DFT)模拟了马来酰肼的红外吸收模式; 在实验和理论频谱数据匹配的情况下, 分析讨论了特征吸收峰的来源, 发现MH2和MH3的THz吸收峰对其三维空间结构非常敏感, 吸收峰均来源于分子间相互作用力。 最后, 为使药物研究能够与实际应用结合, 对马来酰肼的商用药品青鲜素进行了THz光谱测试, 通过其与马来酰肼多形态的THz吸收峰比较, 发现人们日常使用的青鲜素是MH3晶型。 此研究结果表明, THz-TDS技术是一种很有潜力的药物多形态检测工具, 此研究有望解决马来酰肼多形态在工业生产及临床应用上检测难的问题。

In this paper, we design a one-dimensional (1D) parity-time-symmetric periodic ring optical waveguide network (PTSPROWN) and investigate its extraordinary optical characteristics. It is found that quite different from traditional vacuum/dielectric optical waveguide networks, 1D PTSPROWN cannot produce a photonic ordinary propagation mode, but can generate simultaneously two kinds of photonic nonpropagation modes: attenuation propagation mode and gain propagation mode. It creates neither passband nor stopband and possesses no photonic band structure. This makes 1D PTSPROWN possess richer spontaneous PT-symmetric breaking points and causes interesting extremum spontaneous PT-symmetric breaking points to appear, where electromagnetic waves can create ultrastrong extraordinary transmission, reflection, and localization, and the maximum can arrive at 6.6556×1012 and is more than 7 orders of magnitude larger than the results reported previously. 1D PTSPROWN may possess potential in designing high-efficiency optical energy saver devices, optical amplifiers, optical switches with ultrahigh monochromaticity, and so on.