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We have demonstrated the realization of a coherent vesicle random lasing (VRL) from the dye doped azobenzene polymer vesicles self-assembled in the tetrahydrofuran-water system, which contains a double-walled structure: a hydrophilic and hydrophobic part. The effect of the dye and azobenzene polymer concentration on the threshold of random laser has been researched. The threshold of random laser decreases with an increase in the concentration of the pyrromethene 597 (PM597) laser and azobenzene polymer. Moreover, the scattering of small size group vesicles is attributed to providing a loop to boost the coherent random laser through the Fourier transform analysis. Due to the vesicles having the similar structure with the cell, the generation of coherent random lasers from vesicles expand random lasers to the biomedicine filed.

To realize multiparameter simultaneous sensing measurement and eliminate cross-sensitivity, we cascade three micro-tapered long-period fiber grating (TLPG) sensors and analyze the transmission characteristics and sensing capabilities of cascaded micro-TLPGs (CTLPGs) in detail. Based on the modulation of the resonant wavelength of the sensor by the change of the surrounding environment, the synchronous real-time detection of refractive index (RI), temperature, and liquid level is realized. The CTLPG sensor not only inherits the advantages of TLPG sensors and reduces the influence of cross-sensitivity when measuring multiparameters but also improves the sensitivity and accuracy of the sensor. The experimental results show that the maximum RI sensitivity is 693 nm/RIU, the maximum temperature sensitivity is −93 pm/°C, and the maximum liquid-level sensitivity is 12 nm/mm. The sensor has a simple structure, low manufacturing cost, high sensitivity, and potential applications in monitoring ocean temperature, salinity, and depth.

A high-performance InGaN/GaN multiple quantum well (MQW) p-i-n photodetector (PD) is fabricated on patterned sapphire substrates (PSSs). The fabricated PD exhibits a low dark current density of $ < 2.0\times 10^{-{10}}$ A/cm2 under a bias voltage of −2 V, with a high photocurrent to dark current contrast ratio of over $10^{{6}}$ . Furthermore, the peak responsivity at the wavelength of 395 nm reaches 0.18 A/W at −10 V, corresponding to a maximum quantum efficiency of approximately 56%. In addition, the noise equivalent power (NEP) and normalized detectivity were found to be $1.14\times 10^{-{11}}$ W and $2.77\times 10^{{11}}$ cm $\cdot $ Hz $^{{0.5}}\,\,\cdot \,\,\text{W}^{-{1}}$ , respectively. The high-performance PD achieved is believed to be related to the high crystalline quality of the InGaN epilayer.

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.

A type of Christiansen filter that takes the form of a smooth cylindrical lens of even symmetry is proposed. By varying the shape of the lens, the filter can be made to realize many common filtering responses, including the polynomial function response, the Gaussian function response, and the sinc function response. A systematic design technique based on inverse scattering is established, and a desired, prescribed response can be tailored by properly shaping the lens of the filter. Three prototypical Christiansen filters, namely, a second-order all-real-roots filter, a second-order sinc filter, and a Gaussian filter, are synthesized using the proposed method. A prescribed response at 545 nm with a FWHM of 2 nm is achieved systematically by all of the three Christiansen filters.

In waveguided nematic liquid crystal random lasers (NLCRLs), we realize polarized random laser (RL) emission and discover that the waveguide effect reduces the transmission loss of the RL whose polarization is parallel to the liquid crystal molecules (LCMs). Compared with the traditional liquid crystal random lasers, the waveguide NLCRLs can achieve the regulation of RLs strength, polarization, and wavelength in the same structure. The electric field can drive the rotation of LCMs to control the RL polarization and intensity. The drop of horizontal polarization laser and the increase of vertical polarization laser prove the role of the waveguide effect. In addition, the disorder of the waveguided NLCRLs is highly sensitive to temperature, which makes it easy to control the wavelength and intensity of the RL. As the temperature rises, the waveguide effect is weakened, resulting in a weakening of the restriction along liquid crystal (LC) cell normal direction. The reduced laser intensity verifies the role of the waveguide effect.

The theoretical basis and experimental realization of an all-fiber self-mixing laser Doppler velocimetry based on frequency-shifted feedback in a distributed feedback (DFB) fiber laser are presented, which employs a pair of fiber-coupled acousto-optic modulators to adjust the modulation intensity and frequency of the laser self-mixing effect. Moreover, the minimum optical feedback intensity for the velocity signal successfully measured by the interferometer is 5.12 fW, corresponding to 0.16 photons per Doppler cycle. The results demonstrate that the proposed scheme can adapt to the non-contact measurement requirements of the wide-range speed and weak feedback level in the complex environment.

This paper systematically demonstrated a variety of experimental phenomena of random lasers (RLs) of N,N′-di-(3-(isobutyl polyhedral oligomeric silsesquioxanes)propyl) perylene diimide (DPP) organic/inorganic hybrid laser dye, which is composed of perylene diimide (PDI) as gain media and polyhedral oligomeric silsesquioxanes (POSS) as scattering media at a mole ratio of 1:2. In this work, we observe the transition from incoherent RL in the DPP-doped solutions and polymer membrane systems using dip-coating method to coherent RL in the polymer membrane system with defect waveguide using semi-polymerization (SP) coating method. Meanwhile, we found that the hybrid dye-DPP has a long lasing lifetime compared with the traditional laser dyes, which indicates that the POSS group can suppress the photo-bleaching effect to extend the working life of laser dyes.

This work presents the synthesis of corrosion inhibitor [1H-benzotriazole (BTA)]-loaded hollow silica nanocapsules with magnesium hydroxide precipitate in the shells (HSNs-M/BTA) through inverse microemulsion (W/O) polymerization. TEM and Brunauer–Emmett–Teller (BET) measurements indicate that the silica nanocapsules possess voids in the inner part and mesoporous on the surface. The actual loading capacity of BTA is 287.17 mg (BTA)/1 g (HSNs-M/BTA). The results of UV absorption spectra show that the release of BTA can be triggered by the changing of pH in the corrosion solution. The anticorrosive SiOx/ZrOxcoatings embedded with hydrophobically modified HSNs-M have a better waterproof performance since the water contact angle can reach 140°. In comparison to the passive SiOx/ZrOxcoatings with or without BTA, the enhanced corrosion protection performance of this developed anticorrosive system was observed by both electrochemical impedance spectroscopy and Tafel analysis. The fabrication of nanocapsules with corrosion inhibitors is promising as an intelligent element in protective coatings in the future.

The large absolute photonic bandgaps of two-dimensional (2D) anisotropic magnetic plasma photonic crystals with hexagonal and square lattices are obtained by introducing tellurium dielectric rods using the modified plane wave expansion method. Equations for calculating the band structures in the irreducible part of the first Brillouin zone are theoretically deduced. The modulation properties indicate that the location and bandwidth of the absolute photonic bandgaps (PBGs) could be tuned by filling factor, plasma frequency, and magnetic field. The effective tunable ranges and critical values of these parameters are found. These results could be helpful in designing 2D anisotropic PPCs with large absolute PBGs.

We demonstrate the realization of a polarized random polymer fiber laser (RPFL) in the different disordered gain media doped polymer optical fibers (POFs). Multiple scattering of disordered media in the orientated POF was experimentally verified to account for polarized lasing observed in our RPFL system. This Letter presents a new avenue for fabricating polarized RPFLs in a large scale. Meanwhile, the polarization-maintaining property of random lasing for different disorder POF are researched, which will open a window to designing a polarization-maintaining random fiber laser.

Optical cavities and waveguides are critical parts of modern optical devices. Traditionally, optical cavities and waveguides rely on photonic bandgaps, or total internal reflection, to achieve light trapping. It has been reported that a novel light trapping, which exists in triangular and honeycomb lattices, is attributed to the so-called Dirac point. Our analysis reveals that 2D triangular Archimedean-like lattice photonic crystals also can support this Dirac mode with similar characteristics. This is a new type of localized mode with a different algebraic field profile at a different specified Dirac frequency, which is also beyond any complete photonic bandgap. The new wave localization has different features and can be applied to the design of new optical devices.

There are many kinds of materials or methods used to make optical microcavities, and they have many different geometric structures. And electrospinning technique has become a very convenient and easy one to prepare polymer fiber. Based on this situation, PM597-doped polymer solution was prepared into high-performance fibers with different diameters by electrospinning technology in our work. In order to better study the temperature sensing of polymer fiber whispering gallery mode, we have placed it on two different substrates with gold and aluminum. A 532 nm pulsed laser beam was used to excite a single fiber in the radial direction, then the whispering gallery mode (WGM) laser was observed and the distribution of WGM was determined by theoretical calculations. The threshold of samples on aluminum substrate is 0.4 μJ. In addition, it is found that the samples on aluminum substrate performed better in temperature sensing, and the value is 0.13 nm/°C. As a result, WGM polymer fiber microcavities on aluminum substrate made by electrospinning technology have very broad development prospects in biosensing, optical pump lasers and other applications.

We demonstrate the realization of two different kinds of random polymer optical fiber lasers to control the random lasing wavelength by changing the disorder of polymer optical fibers (POFs). One is a long-range disorder POF based on copolymer refractive-index inhomogeneity, and the other is a short-range disorder POF based on polyhedral oligomeric silsesquioxanes scattering. By end pumped both disorder POFs, the coherent random lasing for both is observed. Meanwhile, the random lasing wavelength of the short-range disorder POF because of a small scattering mean-free path has been found to be blue shifted with respect to the long-range disorder POF, which will give a way to control the random lasing wavelength.

We have demonstrated the realization of a random polymer fiber laser (RPFL) based on laser dye Pyrromethene 597-doped one-dimensional disordered polymer optical fiber (POF). The stabilized coherent laser action for the disordered POF has been obtained by the weak optical multiple scattering of the polyhedral oligomeric silsesquioxanes nanoparticles in the core of the POF in situ formed during polymerization, which was enhanced by the waveguide confinement effect. Meanwhile, the threshold of our RPFL system is almost one order of magnitude lower than that of the liquid core random fiber laser reported previously, which promotes the development of random lasers.

A liquid core optical fiber (LCOF) composed of hollow fiber and a solution of Eu(TTA)_3Phen (TTA=2-thenoyltrifluoroacetone, Phen=1, 10-phenanthroline) in dimethyl sulfoxide (DMSO) has been fabricated, in which the concentration of Eu(TTA)_3Phen in DMSO is 0.8?wt.%, the core diameter of the LCOF is 10?μm, and the fiber length is 8.1?cm. By the end pumping with a diode-pumped solid-state laser at 355?nm, a small optical signal at 613?nm was amplified with a gain of 8.2?dB at a pump power of 203?mW. Based on this experimental result, a liquid core optical fiber amplifier can be realized by the LCOF, which has wide potential applications in many optical devices.