Replica symmetry breaking (RSB) has been widely recognized as a statistical analysis approach to understand the disorder and nonlinear interactions in complex systems ranging from atoms to the cosmic scale. However, it is challenging to analyze the nonlinear optical characteristics of random laser (RL) in disordered gain medium via RSB due to the lack of a general RSB‐based statistical analysis framework. In this work, we report the tunable RSB in polymer fiber RL, where the effects of temperature and different structures on RSB are investigated experimentally and theoretically. It experimentally proves that RSB in RL is not robust, and disorder and temperature are responsible for tunable RSB in RL, which contributes to the improvement of the statistical analysis framework for investigating the optical principles of RL using RSB. And the finding of the tunable RSB allows to investigate the dynamical differences for various RL systems, which broadens the directions for the use of spin‐glass theory to explore the physical mechanism of RL.

Monitoring glucose levels is one of the main diagnostic methods for preventing and treating diabetes. Conventionally monitoring of blood glucose through a finger-stick procedure brings pain. It is essential to develop biosensors for low concentration glucose detection in non-invasive samples. In this paper, a tilted fiber grating based localized surface plasmon resonance (LSPR) biosensor for ultrasensitive glucose detection has been demonstrated. The glucose biosensor was fabricated by immobilization of Au nanoparticles (AuNPs) onto an excessively tilted fiber grating (Ex-TFG) and subsequent biofunctionalization by coating polydopamine and concanavalin A onto the AuNPs/Ex-TFG surface. The biosensor has the response regions covering low, middle and high glucose concentrations. The resonance peak indicates a redshift of 0.24 nm, 0.06 nm and 0.48 nm in the concentration ranges of 1.0 nM $- 1.0\,\, \boldsymbol {\mu }\text{M}$ , $1.0\,\, \boldsymbol {\mu }\text{M}- 50.0\,\, \boldsymbol {\mu }\text{M}$ and $50.0\,\, \boldsymbol {\mu }\text{M}-5.0$ mM, respectively. The limit of detection (LOD) of the biosensor in pure phosphate buffered saline is 2.5 nM. The high sensitivity and specific selectivity for D-glucose detection are attributed to strong coupling between the evanescent fields from transverse magnetic (TM) cladding modes of the Ex-TFG and the localized electric fields from LSPR of the AuNPs and their biofunctionalization, and resulting in remarkable enhancement of localized effective refractive index with slightly increased D-glucose concentration. Especially, the glucose biosensor based on the Ex-TFG coupled with the biofunctionalized AuNPs, has been demonstrated to be of practical utility to detect the glucose in artificial urine, which has potential applications in non-invasive glucose monitoring for early diagnosis and better management of diabetes.

By filling the liquid crystal (LC) in the air holes of a photonic crystal fiber (PCF) with 8 mm length, a compact multi-band thermal optical switch is proposed here including two important telecommunication band, i.e., 1265 to 1317 nm and 1508 to 1568 nm. Within the bandwidth, the extinction ratio can be as high as 30 dB. Under the combined action of the bandgap-guiding mechanism and the interference effect, a temperature change of only 1 °C after clearing temperature (T _c ) of the LC induces multi-band thermal optical switch of the LC-filled PCF. It is also noted that the transmission spectrum of the LC-filled PCF is quite sensitive to the ambient temperature. The consequent thermal sensitive is 3.9 nm/°C, making it a very good candidate for monitoring the temperature herein.

Eu2+-activated phosphors are widely applied in lighting and display areas because of their good optical performance. In this paper, an excellent green-emitting zeolite-3A: 1.3 wt% Eu phosphor is prepared by a green and eco-friendly high-thermal reaction method without any reducing atmosphere or agents. Meanwhile, the reducing mechanism from Eu3+ ions to Eu2+ ions is investigated. The experiment results show that the morphology, crystal structure, and luminescent property are affected by sintering temperature. The resulting sample shows the broad excitation band is in the range of 310–450 nm and the peak of the broad emission band is located at 523 nm. Furthermore, zeolite-3A: 1.3 wt% Eu phosphor is encapsulated on a commercial UV-emitting chip to fabricate a purity green light-emitting diode (LED) with the Commission Internationale de L’Eclairage (CIE) color coordinates at (0.295, 0.537).