An 8-Connected Chiral Lanthanide Metal-organic Framework Constructed from Naturally Camphoric Acid:Crystal Structure,Vibrational Circular Dichroism Spectroscopy and Second-order Nonlinear Optical Effect

A chiral lanthanide metal-organic framework based on enantiopure camphoric acid （D-H2cam）, [Nd3（D-cam）8（H2O）4Cl]n （1）, has been synthesized and characterized by single-crystal X-ray structural analysis, elemental analysis, IR, thermal gravimetric, and X-ray powder diffraction. Crystal data for the title compound are as follows： orthorhombic system, space group P212121 with a = 13.8287（7）, b = 14.0715（7）, c = 25.7403（12） A^°, V = 5008.8（4） A^°3, Mr = 1333.08, Z = 4, F（000） = 2644, Dc = 1.768 g/cm^3, μ（MoKα） = 3.189 mm^-1, the final R = 0.0351 and wR = 0.0814 （I 〉 2σ（I））. Compound 1 displays an 8-connected bcu topology 3D framework and hydrogen-bonding interactions stabilize the solid-state structure. The vibrational circular dichroism （VCD） spectrum and second-order nonlinear optical effect of compound 1 have been studied in the solid state.

Bioapplications Manipulated by AIEgens with Nonlinear Optical Effect

The modern medicine requires precise diagnostic techniques while the fluorescent imaging shows great potential in such applications due to its excellent sensitivity and high resolution.However,conducting fluorescent imaging in deep-tissue is not so easy because most luminogens show short-wavelength excitation,which may undergo severe light scattering by the bio-tissue.The marriage of fluorescent imaging with nonlinear optical(NLO)effect can alleviate such adverse effects by utilizing NIR laser to reduce light scattering.On the other hand,scientists are enthusiastic in pursuing luminescent materials,which can match well with NLO application.Aggregation-induced emission(AIE)materials exhibit huge advantages in such aspect not only because of its high luminescent efficiency in aggregate state but also due to its excellent photo-stability(a key factor to meet laser application because of its ultrahigh energy density).Inspired by this,many interesting and meaningful works have sprung up based on AIE luminogens with NLO effect in recent years,and for such reason,it motivates us to summarize them to give a systematic presentation.Here,we first give a brief introduction of the principle of NLO effect.Secondly,the strategies for improving the NLO effect of AIE materials,such as increasing molecular conjugation,introduction of donor-acceptor effect,induction of centrally asymmetric array of AIE molecules in crystals and introduction of intermolecular interactions are clarified.In the final part,we also present the multiple applications of AIEgens with NLO effect in cell imaging,deep-tissue tumor and brain blood vessel imaging and photodynamic therapy.We believe,with this review,the topic will attract more attention from the scientists in multi-science field to accelerate the development of AIE materials in biomedical applications.

Incoherently coupled soliton pairs in nonlocal nonlinear media

We show that incoherently coupled soliton pairs can exist in nonlocal Kerr-type nonlinear media. Such solitons can propagate in bright--bright, dark--dark, and gray--gray configurations. When the nonlocal nonlinearity is absent, these bright--bright and dark--dark soliton pairs are those observed previously in local Kerr-type nonlinear media. Our analysis indicates that for a self-focusing nonlinearity the intensity full width half maximum （FWHM） of the bright--bright pair components increases with the degree of nonlocality of the nonlinear response, whereas for a self-defocusing nonlinearity the intensity FWHM of the dark--dark and gray--gray pair components decreases with the increase in the degree of nonlocality of the nonlinear response. The stability of these soliton pairs has been investigated numerically and it has been found that they are stable.

Optical super-resolution effect induced by nonlinear characteristics of graphene oxide films

In this work, we focus on the optical super-resolution effect induced by strong nonlinear saturation absorption(NSA) of graphene oxide(GO) membranes. The third-order optical nonlinearities are characterized by the canonical Z-scan technique under femtosecond laser(wavelength: 800 nm, pulse width: 100 fs) excitation. Through controlling the applied femtosecond laser energy, NSA of the GO films can be tuned continuously. The GO film is placed at the focal plane as a unique amplitude filter to improve the resolution of the focused field. A multi-layer system model is proposed to present the generation of a deep sub-wavelength spot associated with the nonlinearity of GO films. Moreover, the parameter conditions to achieve the best resolution(~λ/6) are determined entirely. The demonstrated results here are useful for high density optical recoding and storage, nanolithography, and super-resolution optical imaging.

Intra-Channel Nonlinear Effect on Optical PPM Pulse Transmission

PPM encoded Gaussian pulse sequence shows more immunity than non-PPM schemes on optical fiber intra-channel nonlinearity and demonstrated by a numerical study of IXPM and IFWM effects deploying on 100Gb/s single channelsystem.

Recent Issues on Nonlinear Effects in Optical Fibers

This talk will discuss the types of optical signal degradation due to fiber nonlinearity and review recently invented fibers for suppressing the effects. It also introduces efficiency of highly nonlinear fibers and their applications to nonlinear signal processing.

Effects of gain nonlinearities in an optically injected gain lever semiconductor laser

The effects of gain compression on the modulation dynamics of an optically injected gain lever semiconductor laser are studied. Calculations reveal that the gain compression is not necessarily a drawback affecting the laser dynamics. With a practical injection strength, a high gain lever effect and a moderate compression value allow us to theoretically predict a modulation bandwidth four times higher than the free-running one without a gain lever,which is of paramount importance for the development of directly modulated broadband optical sources compatible with short-reach communication links.

Correction of walk-off-induced wavefront distortion for continuous-wave laser

We theoretically and experimentally investigate the wave front distortion in critically phase-matched continuouswave（CW） second harmonic generation（SHG）.Due to the walk-off effect in the nonlinear crystal,the generated second harmonic is extremely elliptical and quite non-Gaussian,which causes a very low matching and coupling efficiency in experiment.Cylindrical lenses and walk-off compensating crystals are adopted to correct distorted wave fronts,and obtain a good TEM00 mode efficiently.Theoretically,we simulate the correction effect of 266-nm laser generated with SHG.The experiment results accord well with the theoretical simulation and an above 80% TEM_（00） component is obtained for 266-nm continuous-wave laser with a 4.8？-walk-off angle in beta barium borate（BBO） crystal.

Monolayer-molybdenum-disulfide-based nano-optomechanical transistor and tunable nonlinear responses

Atomically thin two-dimensional semiconductor nanomaterials have attained considerable attention currently. Here, we present a nano-optomechanical system based on a suspended monolayer molybdenum disulfide （MoS2）. The linear and nonlinear coherent optical properties of this system, and the phenomenon ofphonon-induced transparency are demonstrated. The transmission of the probe field can be manipulated by the power of a second ‘gating＇ （pump） field, which indicates a promising candidate for an optical transistor. We further study the nonlinear effect of the system, and the optical Kerr effect of the monolayer MoS2 resonator can be regulated under different parameter regimes. This scheme proposed here may indicate potential chip-scale applications of monolayer MoS2 resonator in quantum information with the currently popular pump-probe technology.

等离激元异质纳米结构的可控制备及其应用

近年来,具有独特光学性质的等离激元纳米材料研究得到了广泛关注.等离激元光学材料与其他功能材料(金属材料或半导体材料)的结合会产生远胜于单组分材料的性质,因此在许多光学应用中展现出优异的性能.本文综述了具有特定成分、形貌、大小和结构对称性的等离激元异质纳米结构可控生长的最新进展,并介绍了其中等离激元增强的性质和应用性能.等离激元异质纳米结构的可控制备和优异性能使其在等离激元增强的非线性光学、光谱学、光催化、光伏等应用中具有巨大的应用前景.