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Materials|11 Article(s)
Antimonene: a long-term stable two-dimensional saturable absorption material under ambient conditions for the mid-infrared spectral region
Hongyu Luo, Xiangling Tian, Ying Gao, Rongfei Wei, Jianfeng Li, Jianrong Qiu, and Yong Liu
We experimentally demonstrate a long-term stable two-dimensional saturable absorption material under ambient conditions—multi-layer antimonene feasible for the mid-infrared spectral region—for the first time to our knowledge. The multi-layer antimonene material prepared using a liquid-phase exfoliation method was coated on a quartz/CaF2 for characterizations and an Au mirror as a reflection-type saturable absorber (SA) device. It has a modulation depth of 10.5%, a saturation peak intensity of 0.26 GW/cm2, and a non-saturation loss of 19.1% measured at 2868.0 nm using the typical power-dependent method. By introducing the SA device into a linear-cavity Ho3+/Pr3+-codoped fluoride fiber laser at 2865.0 nm, stable Q-switched pulses were obtained. It generated a maximum output power of 112.3 mW and pulse energy of 0.72 μJ, while the shortest pulse duration and largest repetition rate were 1.74 μs and 156.2 kHz, respectively. The long-term stability of the SA device was also checked using the same laser setup within 28 days. The results indicate that multi-layer antimonene is a type of promising long-term stable SA material under ambient conditions that can be applied in the mid-infrared spectral region. We experimentally demonstrate a long-term stable two-dimensional saturable absorption material under ambient conditions—multi-layer antimonene feasible for the mid-infrared spectral region—for the first time to our knowledge. The multi-layer antimonene material prepared using a liquid-phase exfoliation method was coated on a quartz/CaF2 for characterizations and an Au mirror as a reflection-type saturable absorber (SA) device. It has a modulation depth of 10.5%, a saturation peak intensity of 0.26 GW/cm2, and a non-saturation loss of 19.1% measured at 2868.0 nm using the typical power-dependent method. By introducing the SA device into a linear-cavity Ho3+/Pr3+-codoped fluoride fiber laser at 2865.0 nm, stable Q-switched pulses were obtained. It generated a maximum output power of 112.3 mW and pulse energy of 0.72 μJ, while the shortest pulse duration and largest repetition rate were 1.74 μs and 156.2 kHz, respectively. The long-term stability of the SA device was also checked using the same laser setup within 28 days. The results indicate that multi-layer antimonene is a type of promising long-term stable SA material under ambient conditions that can be applied in the mid-infrared spectral region.
Photonics Research
- Publication Date: Aug. 23, 2018
- Vol. 6, Issue 9, 09000900 (2018)
Vertically standing PtSe2 film: a saturable absorber for a passively mode-locked Nd:LuVO4 laser
Lili Tao, Xiaowen Huang, Junshan He, Yajun Lou, Longhui Zeng, Yonghui Li, Hui Long, Jingbo Li, Ling Zhang, and Yuen Hong Tsang
The novel vertically standing PtSe2 film on transparent quartz was prepared by selenization of platinum film deposited by the magnetron sputtering method, and an Nd:LuVO4 passively mode-locked solid-state laser was realized by using the fabricated PtSe2 film as a saturable absorber. The X-ray diffraction pattern and Raman spectrum of the film indicate its good crystallinity with a layered structure. The thickness of PtSe2 film is measured to be 24 nm according to the cross-section height profile of the atomic force microscope image. High-resolution transmission electron microscopy images clearly demonstrate its vertically standing structure with an interlayer distance of 0.54 nm along the c-axis direction. The modulation depth (ΔT) and saturation fluence ( s) of PtSe2 film are measured to be 12.6% and 17.1 μJ/cm2, respectively. The obtained mode-locked laser spectrum has a central wavelength of 1066.573 nm, with a 3 dB bandwidth of 0.106 nm. The transform limited pulse width of the mode-locked laser was calculated to be 15.8 ps. A maximum average output power of 180 mW with a working repetition rate of 61.3 MHz is obtained. To the best of our knowledge, this is the first report of the generation of ultrafast mode-locked laser pulses by using layered PtSe2 as a saturable absorber. The novel vertically standing PtSe2 film on transparent quartz was prepared by selenization of platinum film deposited by the magnetron sputtering method, and an Nd:LuVO4 passively mode-locked solid-state laser was realized by using the fabricated PtSe2 film as a saturable absorber. The X-ray diffraction pattern and Raman spectrum of the film indicate its good crystallinity with a layered structure. The thickness of PtSe2 film is measured to be 24 nm according to the cross-section height profile of the atomic force microscope image. High-resolution transmission electron microscopy images clearly demonstrate its vertically standing structure with an interlayer distance of 0.54 nm along the c-axis direction. The modulation depth (ΔT) and saturation fluence ( s) of PtSe2 film are measured to be 12.6% and 17.1 μJ/cm2, respectively. The obtained mode-locked laser spectrum has a central wavelength of 1066.573 nm, with a 3 dB bandwidth of 0.106 nm. The transform limited pulse width of the mode-locked laser was calculated to be 15.8 ps. A maximum average output power of 180 mW with a working repetition rate of 61.3 MHz is obtained. To the best of our knowledge, this is the first report of the generation of ultrafast mode-locked laser pulses by using layered PtSe2 as a saturable absorber.
Photonics Research
- Publication Date: Jun. 29, 2018
- Vol. 6, Issue 7, 07000750 (2018)
Graphene-enabled electrically controlled terahertz meta-lens
Weiguang Liu, Bin Hu, Zongduo Huang, Hongyu Guan, Heting Li, Xinke Wang, Yan Zhang, Hongxing Yin, Xiaolu Xiong, Juan Liu, and Yongtian Wang
Metasurfaces have become a new photonic structure for providing potential applications to develop integrated devices with small thickness, because they can introduce an abrupt phase change by arrays of scatterers. To be applied more widely, active metasurface devices are highly desired. Here, a tunable terahertz meta-lens whose focal length is able to be electrically tuned by ～4.45λ is demonstrated experimentally. The lens consists of a metallic metasurface and a monolayer graphene. Due to the dependence of the abrupt phase change of the metasurface on the graphene chemical potential, which can be modulated using an applied gate voltage, the focal length is changed from 10.46 to 12.24 mm when the gate voltage increases from 0 to 2.0 V. Experimental results are in good agreement with the theoretical hypothesis. This type of electrically controlled meta-lens could widen the application of terahertz technology. Metasurfaces have become a new photonic structure for providing potential applications to develop integrated devices with small thickness, because they can introduce an abrupt phase change by arrays of scatterers. To be applied more widely, active metasurface devices are highly desired. Here, a tunable terahertz meta-lens whose focal length is able to be electrically tuned by ～4.45λ is demonstrated experimentally. The lens consists of a metallic metasurface and a monolayer graphene. Due to the dependence of the abrupt phase change of the metasurface on the graphene chemical potential, which can be modulated using an applied gate voltage, the focal length is changed from 10.46 to 12.24 mm when the gate voltage increases from 0 to 2.0 V. Experimental results are in good agreement with the theoretical hypothesis. This type of electrically controlled meta-lens could widen the application of terahertz technology.
Photonics Research
- Publication Date: Jun. 20, 2018
- Vol. 6, Issue 7, 07000703 (2018)
Multifunctional metasurface: from extraordinary optical transmission to extraordinary optical diffraction in a single structure
Zi-Lan Deng, Yaoyu Cao, Xiangping Li, and Guo Ping Wang
We show that a metasurface composed of a subwavelength metallic slit array embedded in an asymmetric dielectric environment can exhibit either extraordinary optical transmission (EOT) or extraordinary optical diffraction (EOD). The cascaded refractive indices of the dielectrics can leverage multiple decaying passages into variant subsections with different diffraction order combinations according to the diffraction order chart in the k-vector space, providing a flexible mean to tailor resonance decaying pathways of the metallic slit cavity mode by changing the wavevector of the incident light. As a result, either the zeroth transmission or 1st reflection efficiencies can be enhanced to near unity by the excitation of the localized slit cavity mode, leading to either EOT or EOD in a single structure, depending on the illumination angle. Based on this appealing feature, a multifunctional metasurface that can switch its functionality between transmission filter, mirror, and off-axis lens is demonstrated. Our findings provide a convenient way to construct multifunctional miniaturized optical components on a single planar device. We show that a metasurface composed of a subwavelength metallic slit array embedded in an asymmetric dielectric environment can exhibit either extraordinary optical transmission (EOT) or extraordinary optical diffraction (EOD). The cascaded refractive indices of the dielectrics can leverage multiple decaying passages into variant subsections with different diffraction order combinations according to the diffraction order chart in the k-vector space, providing a flexible mean to tailor resonance decaying pathways of the metallic slit cavity mode by changing the wavevector of the incident light. As a result, either the zeroth transmission or 1st reflection efficiencies can be enhanced to near unity by the excitation of the localized slit cavity mode, leading to either EOT or EOD in a single structure, depending on the illumination angle. Based on this appealing feature, a multifunctional metasurface that can switch its functionality between transmission filter, mirror, and off-axis lens is demonstrated. Our findings provide a convenient way to construct multifunctional miniaturized optical components on a single planar device.
Photonics Research
- Publication Date: Apr. 23, 2018
- Vol. 6, Issue 5, 05000443 (2018)
Broadening and enhancing 2.7 μm emission spectra in Er/Ho co-doped oxyfluoride germanosilicate glass ceramics by imparting multiple local structures to rare earth ions
Qunhuo Liu, Ying Tian, Wenhua Tang, Feifei Huang, Xufeng Jing, Junjie Zhang, and Shiqing Xu
Er/Ho co-doped oxyfluoride germanosilicate glass and glass ceramics are prepared and compared. The results indicate that the glass consists of SiO4 and GeO4 structural units, while the network of the glass ceramics consists of SiO4, GeO4, and GeO6 units together with NaYF4 nanocrystals. The presence of multiple local structures in glass ceramics creates a range of dipole environments, which is beneficial to the broadening of 2.7 μm emission. Two other reasons are attributed to the broadening of 2.7 μm emission in glass ceramics: the energy-level splitting of Er3+ and the enhancement of the Ho3+:I65→I75 transition in NaYF4 nanocrystals. Er/Ho co-doped oxyfluoride germanosilicate glass and glass ceramics are prepared and compared. The results indicate that the glass consists of SiO4 and GeO4 structural units, while the network of the glass ceramics consists of SiO4, GeO4, and GeO6 units together with NaYF4 nanocrystals. The presence of multiple local structures in glass ceramics creates a range of dipole environments, which is beneficial to the broadening of 2.7 μm emission. Two other reasons are attributed to the broadening of 2.7 μm emission in glass ceramics: the energy-level splitting of Er3+ and the enhancement of the Ho3+:I65→I75 transition in NaYF4 nanocrystals.
Photonics Research
- Publication Date: Mar. 29, 2018
- Vol. 6, Issue 4, 04000339 (2018)
Optical properties and applications for MoS2-Sb2Te3-MoS2 heterostructure materials
Wenjun Liu, Ya-Nan Zhu, Mengli Liu, Bo Wen, Shaobo Fang, Hao Teng, Ming Lei, Li-Min Liu, and Zhiyi Wei
Two-dimensional (2D) materials with potential applications in photonic and optoelectronic devices have attracted increasing attention due to their unique structures and captivating properties. However, generation of stable high-energy ultrashort pulses requires further boosting of these materials’ optical properties, such as higher damage threshold and larger modulation depth. Here we investigate a new type of heterostructure material with uniformity by employing the magnetron sputtering technique. Heterostructure materials are synthesized with van der Waals heterostructures consisting of MoS2 and Sb2Te3. The bandgap, carrier mobility, and carrier concentration of the MoS2-Sb2Te3-MoS2 heterostructure materials are calculated theoretically. By using these materials as saturable absorbers (SAs), applications in fiber lasers with Q-switching and mode-locking states are demonstrated experimentally. The modulation depth and damage threshold of SAs are measured to be 64.17% and 14.13 J/cm2, respectively. Both theoretical and experimental results indicate that MoS2-Sb2Te3-MoS2 heterostructure materials have large modulation depth, and can resist high power during the generation of ultrashort pulses. The MoS2-Sb2Te3-MoS2 heterostructure materials have the advantages of low cost, high reliability, and suitability for mass production, and provide a promising solution for the development of 2D-material-based devices with desirable electronic and optoelectronic properties. Two-dimensional (2D) materials with potential applications in photonic and optoelectronic devices have attracted increasing attention due to their unique structures and captivating properties. However, generation of stable high-energy ultrashort pulses requires further boosting of these materials’ optical properties, such as higher damage threshold and larger modulation depth. Here we investigate a new type of heterostructure material with uniformity by employing the magnetron sputtering technique. Heterostructure materials are synthesized with van der Waals heterostructures consisting of MoS2 and Sb2Te3. The bandgap, carrier mobility, and carrier concentration of the MoS2-Sb2Te3-MoS2 heterostructure materials are calculated theoretically. By using these materials as saturable absorbers (SAs), applications in fiber lasers with Q-switching and mode-locking states are demonstrated experimentally. The modulation depth and damage threshold of SAs are measured to be 64.17% and 14.13 J/cm2, respectively. Both theoretical and experimental results indicate that MoS2-Sb2Te3-MoS2 heterostructure materials have large modulation depth, and can resist high power during the generation of ultrashort pulses. The MoS2-Sb2Te3-MoS2 heterostructure materials have the advantages of low cost, high reliability, and suitability for mass production, and provide a promising solution for the development of 2D-material-based devices with desirable electronic and optoelectronic properties.
Photonics Research
- Publication Date: Feb. 28, 2018
- Vol. 6, Issue 3, 03000220 (2018)
Anomalous transport of light at the phase transition to localization: strong dependence with incident angle
Ernesto Jimenez-Villar, M. C. S. Xavier, Niklaus U. Wetter, Valdeci Mestre, Weliton S. Martins, Gabriel F. Basso, V. A. Ermakov, F. C. Marques, and Gilberto F. de Sá
There has been a growing interest in disordered optical media in recent years due to their potential applications in solar collectors, random lasers, light confinement, and other advanced photonic functions. This paper studies the transport of light for different incidence angles in a strongly disordered optical medium composed of core-shell TiO2@Silica nanoparticles suspended in an ethanol solution. A decrease of optical conductance and an increase of absorption near the input border are reported when the incidence angle increases. The specular reflection, measured for the photons that enter the sample, is lower than the effective internal reflection undergone by the coherently backscattered photons in the exact opposite direction, indicating a nonreciprocal propagation of light. This study represents a novel approach in order to understand the complex physics involved at the phase transition to localization. There has been a growing interest in disordered optical media in recent years due to their potential applications in solar collectors, random lasers, light confinement, and other advanced photonic functions. This paper studies the transport of light for different incidence angles in a strongly disordered optical medium composed of core-shell TiO2@Silica nanoparticles suspended in an ethanol solution. A decrease of optical conductance and an increase of absorption near the input border are reported when the incidence angle increases. The specular reflection, measured for the photons that enter the sample, is lower than the effective internal reflection undergone by the coherently backscattered photons in the exact opposite direction, indicating a nonreciprocal propagation of light. This study represents a novel approach in order to understand the complex physics involved at the phase transition to localization.
Photonics Research
- Publication Date: Sep. 07, 2018
- Vol. 6, Issue 10, 10000929 (2018)
1.54 μm photoluminescence enhancenment of Er3+-doped ZnO films containing nc-Ge: joint effect from Er3+ local environment changing and energy transfer of nc-Ge
Ranran Fan, Fei Lu, and Kaikai Li
ZnO films containing Er and Ge nanocrystals (nc-Ge) were synthesized and their photoluminescence (PL) properties were studied. Visible and near-infrared PL intensities are found to be greatly increased in nc-Ge-containing film. Er-related 1.54 μm emission has been investigated under several excitation conditions upon different kinds of Ge, Er codoped ZnO thin films. 1.54 μm PL enhancement accompanied by the appearance of nc-Ge implies a significant correlation between nc-Ge and PL emission of Er3+. The increased intensity of 1.54 μm in Ge:Er:ZnO film is considered to come from the joint effect of the local potential distortion around Er3+ and the possible energy transfer from nc-Ge to Er3+. ZnO films containing Er and Ge nanocrystals (nc-Ge) were synthesized and their photoluminescence (PL) properties were studied. Visible and near-infrared PL intensities are found to be greatly increased in nc-Ge-containing film. Er-related 1.54 μm emission has been investigated under several excitation conditions upon different kinds of Ge, Er codoped ZnO thin films. 1.54 μm PL enhancement accompanied by the appearance of nc-Ge implies a significant correlation between nc-Ge and PL emission of Er3+. The increased intensity of 1.54 μm in Ge:Er:ZnO film is considered to come from the joint effect of the local potential distortion around Er3+ and the possible energy transfer from nc-Ge to Er3+.
Photonics Research
- Publication Date: Sep. 11, 2017
- Vol. 5, Issue 6, 06000567 (2017)
Tunable luminescent CsPb2Br5 nanoplatelets: applications in light-emitting diodes and photodetectors
Ceng Han, Cunlong Li, Zhigang Zang, Ming Wang, Kuan Sun, Xiaosheng Tang, and Jihe Du
Unlike organic–inorganic hybrid perovskites, all-inorganic cesium lead halide perovskites hold great promise for developing high-performance optoelectronic devices, owing to their improved stability. Herein, we investigate the perovskite-related CsPb2Br5 nanoplatelets (NPLs) with tunable emission wavelengths via changing the reaction temperatures to 100°C, 120°C, and 140°C. Reaction temperature plays a key role in determining the shapes and thicknesses of the resulting CsPb2Br5 NPLs. A higher temperature is in favor of the formation of smaller and thicker NPLs. To develop their potential applications in optoelectronic devices, green light emitting diodes (LEDs) and photodetectors based on CsPb2Br5 NPLs are fabricated. The green LEDs based on CsPb2Br5 NPLs synthesized at 140°C exhibit an excellent pure green emission (full width at half-maximum of <20 nm) and display a luminous efficiency of 34.49 lm/W under an operation current of 10 mA. Moreover, the photodetector based on CsPb2Br5 NPLs synthesized at 100°C has better performance with a rise time of 0.426 s, a decay time of 0.422 s, and a ratio of the current (with and without irradiation) of 364%. Unlike organic–inorganic hybrid perovskites, all-inorganic cesium lead halide perovskites hold great promise for developing high-performance optoelectronic devices, owing to their improved stability. Herein, we investigate the perovskite-related CsPb2Br5 nanoplatelets (NPLs) with tunable emission wavelengths via changing the reaction temperatures to 100°C, 120°C, and 140°C. Reaction temperature plays a key role in determining the shapes and thicknesses of the resulting CsPb2Br5 NPLs. A higher temperature is in favor of the formation of smaller and thicker NPLs. To develop their potential applications in optoelectronic devices, green light emitting diodes (LEDs) and photodetectors based on CsPb2Br5 NPLs are fabricated. The green LEDs based on CsPb2Br5 NPLs synthesized at 140°C exhibit an excellent pure green emission (full width at half-maximum of <20 nm) and display a luminous efficiency of 34.49 lm/W under an operation current of 10 mA. Moreover, the photodetector based on CsPb2Br5 NPLs synthesized at 100°C has better performance with a rise time of 0.426 s, a decay time of 0.422 s, and a ratio of the current (with and without irradiation) of 364%.
Photonics Research
- Publication Date: Aug. 20, 2017
- Vol. 5, Issue 5, 05000473 (2017)
Thermal and luminescent properties of 2 μm emission in thulium-sensitized holmium-doped silicate-germanate glass
Rong Chen, Ying Tian, Bingpeng Li, Xufeng Jing, Junjie Zhang, Shiqing Xu, Hellmut Eckert, and Xianghua Zhang
In this paper, we present the luminescent properties of Tm3+∕Ho3+ co-doped new glass. A series of silicategermanate glass was prepared by the conventional melt-quenching method. In the Tm3+∕Ho3+ co-doped silicategermanate glass, a strong emission of 2 μm originating from the Ho3+:5I7 → 5I8 transition can be observed under conventional 808 nm pumping. The characteristic temperatures, structure, and absorption spectra have been measured. The radiative properties of Ho33+ in the prepared glass were calculated. The emission cross section of Ho33+ ions transition can reach 4.78 × 10?21 cm2 around 2 μm, and the FWHM is as high as 153 nm. The energy transfer efficiency between Ho3+ and Tm3+ has a large value (52%), which indicates the Tm3+∕Ho3+ co-doped silicategermanate glass is a suitable candidate for the 2 μm laser. Moreover, the energy transfer mechanism between Tm3+ and Ho3+ ions was investigated.(61370049, 61308090, 61405182, 51172252, 51372235, 51472225); International Science & Technology Cooperation Program of China (2013DFE63070); Public TechnicalInternational Cooperation Project of the Science Technology Department of Zhejiang Province (2015c340009). In this paper, we present the luminescent properties of Tm3+∕Ho3+ co-doped new glass. A series of silicategermanate glass was prepared by the conventional melt-quenching method. In the Tm3+∕Ho3+ co-doped silicategermanate glass, a strong emission of 2 μm originating from the Ho3+:5I7 → 5I8 transition can be observed under conventional 808 nm pumping. The characteristic temperatures, structure, and absorption spectra have been measured. The radiative properties of Ho33+ in the prepared glass were calculated. The emission cross section of Ho33+ ions transition can reach 4.78 × 10?21 cm2 around 2 μm, and the FWHM is as high as 153 nm. The energy transfer efficiency between Ho3+ and Tm3+ has a large value (52%), which indicates the Tm3+∕Ho3+ co-doped silicategermanate glass is a suitable candidate for the 2 μm laser. Moreover, the energy transfer mechanism between Tm3+ and Ho3+ ions was investigated.(61370049, 61308090, 61405182, 51172252, 51372235, 51472225); International Science & Technology Cooperation Program of China (2013DFE63070); Public TechnicalInternational Cooperation Project of the Science Technology Department of Zhejiang Province (2015c340009).
Photonics Research
- Publication Date: Jan. 01, 2016
- Vol. 4, Issue 6, 06000214 (2016)
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