Identifying self-trapped excitons in 2D perovskites by Raman spectroscopy [Invited]
Junze Li, Junchao Hu, Jiaqi Ma, Xinglin Wen, and Dehui Li
Two-dimensional (2D) perovskites exhibit broadband emission due to strong exciton–phonon coupling-induced self-trapped excitons and thus would find important applications in the field of white-light emitting devices. However, the available identifying methods for self-trapped excitons are currently rather limited and complex. Here, we identify the existence of self-trapped excitons by Raman spectroscopy in both excited and non-excited states. Under excited states, the shifting of the Raman peak indicates the presence of the lattice distortion, which together with the extra Raman scattering peak reveals the presence of self-trapped excitons. Our work provides an alternative simple method to study self-trapped excitons in 2D perovskites.
  • Jul. 23, 2021
  • Chinese Optics Letters
  • Vol.19 Issue, 10 103001 (2021)
  • DOI:10.3788/COL202119.103001
Multi-focused droplet lens array inspired by movable-type printing technology
Bo Dai, Zhengmeng Zhou, Yan Long, Mingliang Pan, Zeyuan Song, and Dawei Zhang
  • Jul. 23, 2021
  • Chinese Optics Letters
  • Vol.19 Issue, 10 102201 (2021)
  • DOI:10.3788/COL202119.102201
High sensitivity cascaded helical-core fiber SPR sensors
Xianbin Wang, Hongchang Deng, and Libo Yuan
The distributed optical fiber surface plasmon resonance (SPR) sensors have attracted wide attention in biosensing and chemical sensing applications. However, due to the limitation of their sensing structure, it is difficult to adjust their resonant wavelength and sensitivity. Here, novel and flexible cascaded helical-core fiber (HCF) SPR sensors are proposed theoretically and experimentally for distributed sensing applications. It is shown that the resonant wavelength and sensitivity of the sensors can be conveniently controlled by adjusting the twist pitch of the helical core. A high sensitivity of 11,180 nm/RIU for refractive-index measurement ranging from 1.355 to 1.365 is realized experimentally when the twist pitch of the helical core is 1.5 mm. It is worth noting that the sensitivity can be further improved by reducing the twist pitch. For example, the sensitivity of the sensor with a twist pitch of 1.4 mm can theoretically exceed 20,000 nm/RIU. This work opens up a new way to implement multi-parameter or distributed measurement, especially to establish sensing networks integrated in a single-core fiber or a multi-core fiber.
  • Jul. 08, 2021
  • Chinese Optics Letters
  • Vol.19 Issue, 9 091201 (2021)
  • DOI:10.3788/COL202119.091201
Liquid crystal integrated metamaterial for multi-band terahertz linear polarization conversion
Shitong Xu, Fei Fan, Hongzhong Cao, Yinghua Wang, and Shengjiang Chang
  • Jun. 15, 2021
  • Chinese Optics Letters
  • Vol.19 Issue, 9 093701 (2021)
  • DOI:10.3788/COL202119.093701