•XRD results showed improved crystallinity of ZnO after doping indium.•All InZnO thin films possess high optical transmittance in visible region.•Photoluminescence (PL) spectra revealed that oxygen vacancy defects dominate in InZnO thin films.•Third order nonlinear optical properties of thin films are found to be enhanced after incorporating indium in ZnO.We proposed the photoluminescence and third order nonlinear optical properties of indium doped zinc oxide (InZnO) thin films with various dopant concentrations. InZnO thin films were grown by simultaneous RF/DC magnetron sputtering technique with different DC power 2 W, 6 W, 8 W and 10 W respectively. The structural characterization and surface morphology of obtained thin films are characterized by XRD and SEM techniques. XRD results revealed that thin film quality is enhanced after doping indium in ZnO. The observed enhanced crystallite size from SEM images agreed with XRD results. In linear optical properties analysis, all ZnO thin films possess high optical transmittance in visible region. The resulted room temperature photoluminescence (RTPL) provided the deeply understanding of optical properties and defect states characteristics. Third order nonlinear optical properties of ZnO thin films were detected using femtosecond Z-scan technique. The domination of oxygen defects (Vo) from RTPL results prohibited direct photon transition in ZnO thin films. But, it leads to observed indirect two photon transition via intermediate defect levels. The self focusing to self defocusing transition when dopant concentration heavily increased also could be interesting result of indium heavily doped ZnO thin film. However, the magnitude of third order nonlinear optical absorption as well as refraction of all ZnO thin films is found to be relatively enhanced with dopant concentration.Download high-res image (130KB)Download full-size image

•β-NaLuF4:Yb3+/Tm3+ nanocrystals with a uniform morphology and hexagonal structure have been prepared by the solvothermal method.•SiO2 hollow capillary enhances the chemical and thermal stability of β-NaLuF4:Yb3+/Tm3+ nanocrystals.•The device can achieve higher sensitivity and accuracy as a high-temperature sensor.Rare earth co-doped nanocrystals of β-NaLuF4: Yb3+/Tm3+ with a uniform morphology and hexagonal structure were synthesized by a solvothermal route. The structure of the synthesized material was investigated with X-ray diffraction, scanning electron microscope and transmission electron microscope techniques. The micro-tube structure including rare earth nanocrystals was achieved by drawing the SiO2 capillary under the flame. The fluorescence intensity ratio of non-thermal coupling levels of 1D2→3F4 and 1G4→3H6 were studied as a function of temperature around the range of 300–550 K. The maximum sensitivity was estimated to be 0.0047 K−1 at 525 K. These results indicated that the device may have great potential applications in optical temperature sensor.

•Crystal quality of ZnO thin films is improved after doping Al in ZnO.•All thin films show high optical transmittance in visible region.•Ultrafast and fast decay processes are dominated in AZO.•Nonlinear optical coefficients are relatively enhanced with Al concentration.Aluminum doped zinc oxide (AZO) thin films were fabricated by simultaneous RF/DC magnetron sputtering technique on sapphire (Al2O3) substrate with different DC sputtering power 2, 6, 8 and 10 W respectively. The sputtered thin films were annealed at 350 °C in order to improve the crystal quality. AZO thin films are systematically analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-VIS spectrometer for structural and optical properties. XRD patterns show that all sputtered thin films are well crystallized with hexagonal wurtzite structure. SEM images reveal the average crystallite sizes are increased after doping Al in ZnO which agreed with the calculated values from XRD. All thin films possess high optical transmittance in visible region and optical band gap values are relatively increased with Al concentration. The ultrafast transient absorption (TA) of AZO was analyzed by femtosecond pump-probe spectroscopy. The kinetic TA curves were fitted by tri-exponential decay function and obtained decay time constants are found to be in few picosecond and nanosecond range for ultrafast and slow processes respectively. Third order nonlinear optical absorption and refraction coefficients were investigated by using Z-scan technique. The observed nonlinear coefficients are enhanced with Al concentration in ZnO.Download high-res image (100KB)Download full-size image

•XRD results of ZnO and InZnO thin films are amorphous and polycrystalline characteristics.•The particle sizes of InZnO are smaller than ZnO thin film.•The linear optical transmittances and bandgap increased after In doping.•Both ZnO and InZnO thin films show positive nonlinear absorption behaviors.•Nonlinar refraction of ZnO thin film is positive.We report the investigation of third order nonlinear optical properties of undoped zinc oxide and indium doped zinc oxide thin films using nanosecond (6 ns, 18 μJ at 532 nm) Z-scan technique. Undoped (ZnO) and indium doped zinc oxide (InZnO) thin films were synthesized on quart silica substrate by using radio frequency (RF) magnetron sputtering technique. The structural and characterization of deposited thin films were analyzed by X-ray diffraction (XRD). In XRD results show different behaviors as amorphous oxide semiconductor and polycrystalline oxide semiconductor for ZnO and InZnO thin films respectively. Elemental compositions of thin films were analyzed by energy dispersive spectrometer (EDS). Surface morphology of ZnO and InZnO films were measured by using scanning electron microscopy (SEM), which show uniform and regular surface with small grain size distribution. Linear optical transmission and reflection thin films were analyzed by UV–VIS spectrometer. The UV–VIS results reveal that the optical transmittances of deposited thin films were increased after doping indium. The third order nonlinear optical properties of ZnO and InZnO thin films were carried out using nanosecond (6 ns) laser Z-scan technique at 532 nm wavelength. In open aperture case, both ZnO and InZnO thin films are show reverse saturable absorption (RSA) behaviors. For close-aperture Z-scan, the transmittance curve of ZnO thin film occurs as valley-peak (positive nonlinear refraction) characteristic, which indicates self-focusing behavior.

A fundamental structure of a passive interleaver based on microring resonator coupled Mach–Zehnder interferometer is proposed in this paper. The most conspicuous advantage is the simplicity, compactness of the structure and the flatness of the passband top. Then we propose two methods of realizing a bandwidth tunability in this structure. A further analysis shows that both methods have their own strengths. We expect the compact and flexible interleaver can provide some potential and important implications for upgrading a hybrid Dense Wavelength Division Multiplexing (DWDM) system.

•We report a novel mild coordination method to synthesize Pc1 and Pc2.•The all-optical switching of Pc2 and Pc1 for the same light intensity is studied.•Pc1 and Pc2 exhibit strong optical limiting effect at nanosecond laser pulses.The nonlinear optical properties of 2,9,16,23-phenoxy-phthalocyanine (Pc1) and 2,9,16,23-phenoxy-phthalocyanine-zinc (Pc2) in solution were investigated under excitation with nanosecond laser pulses at 532 nm. Based on five-level model, the nonlinear absorption in nanosecond regime was theoretically analyzed. The A-OS and OL behavior of Pc1 and Pc2 were further investigated with the pump–probe technique and transmission measurement technique. The results show that the A-OS response time is determined by the lifetime of the first triplet excited state of molecule, and Pc1 and Pc2 exhibit strong optical limiting effect at nanosecond laser pulses. These studies make the samples a promising possibility for device realization.

The all-optical switching (A-OS) response time characteristics of the C60/toluene solution are investigated. Experimental measurement results show that the lifetime of the first triplet excited state of the particle C60 is about 280 ns (the A-OS response time), when the intensity of the pump light reaches to I0=1.34×105 W/cm2. Moreover, analysis of modulation characteristics of A-OS shows that the stronger the light intensity of the pump light is, the smaller the normalized transmittance is, and the lower the A-OS response time is. Under the modulation excitation of the pump, the C60/toluene solutions have great modulation characteristic of A-OS.

The pump–probe technique and transmission measurement technique were used to study the all-optical switching (A-OS) and optical limiting (OL) behavior of 2, 9, 16, 23-phenoxy-phthalocyanine (Pc1) and 2, 9, 16, 23-phenoxy-phthalocyanine-zinc (Pc2) in predominantly the monomeric solution form. The results show that the A-OS response time of Pc2 is longer than that of Pc1, and switch-off and -on times of A-OS for Pc2 are 1.2 and 11.6 μs and for Pc1 are 2.3 and 7.8 μs at the same intensity. Moreover, the results of OL experiments reveal that Pc1 and Pc2 exhibit strong OL effect at nanosecond laser pulses. These studies make the samples a promising possibility for device realization.Highlights► The A-OS response time for Pc2 are 1.2 and 11.6 μs and Pc1 are 2.3 and 7.8 μs. ► The results reveal that Pc1 and Pc2 exhibit strong optical limiting effect. ► The A-OS response time is determined by the lifetime T1 of molecule. ► The results reveal that the OL efficiency is dependent on the concentration.

We investigate the propagation properties in microspheres coupled with a fiber taper system. The resonant properties display the properties of coupled resonator induced transparency and coupled resonator induced absorption. The transmission amplitudes for the various cases are compared and analyzed in the complex plane. Our results indicate that the switch between superluminal and subluminal light propagation can be realized by doping the gain medium in the multiple microspheric resonators.Highlights► We investigate the propagation properties in microspheres coupled with a fiber taper system. ► The resonant properties display the properties of coupled resonator induced transparency and coupled resonator induced absorption. ► The transmission amplitudes for the various cases are compared and analyzed in the complex plane. ► Our results indicate the switch between fast and slow light can be realized by doping the gain medium in multiple microspheric resonators.