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Waterproof Cesium Lead Bromide Perovskite Lasers and Their Applications in Solution
摘要： The many advantageous optoelectronic properties of lead halide perovskites have made them promising materials in both solar cells and light source applications. However, lead halide perovskites are soluble in polar solvents, which hinders their practical applications. Thus, the effective protection of perovskite against polar solvents is of great significance. Herein, we report waterproof CsPbBr3 nanoplate (NP) laser protected by large-scale on-chip micro process compatible atomic layer deposition (ALD) Al2O3. 50 nm Al2O3 coated CsPbBr3 NPs can continuously lase in water for over an hour, and can still lase after being immersed in water for a month. Moreover, the lasing behaviors of the 20 nm Al2O3 coated CsPbBr3 NP, in the mixed solution of water and glycerine with the refractive index ranging from 1.33 to 1.47, are also studied. As the environmental refractive index increases, the NP laser goes through a mode selection process, showing single-mode (540.3 nm) to dual-mode and to single-mode (533.9 nm) lasing behavior, which is caused by mode competition resulting from the decrease of quality factor (Q factor) and the blue-shift of the material’s gain spectra. Besides, lasing thresholds of the CsPbBr3 NP increase with the environmental refractive index, which can be utilized for sensing with a measured sensitivity of 129.7 μJ cm?2 RIU?1 (per refractive index unit) (388.2 μJ cm?2 RIU?1) for the long (short) wavelength lasing mode. Our work demonstrates that the ALD Al2O3 protection method can effectively protect CsPbBr3 against polar solvents, enhance the material’s stability, and enable perovskite’s practical applications in both on-chip integration and solvent systems.
关键词： cesium lead bromide,waterproof,nanolaser,refractive index sensor,perovskite
更新于2025-09-12 10:27:22
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1.5?μm spectral band laser power modulation multilayer graphene refractive index
摘要： Multilayer graphene refractive index (RI) modulation over laser power between 0.6 and 14.3 mW at 1500 nm to 1620 nm wavelength band is performed based on a half graphene cladding fiber Bragg grating (FBG), coming from an FBG, which half is cladding etched and coated with graphene, and another half of the FBG is remained. By measuring the wavelength difference between these two parts of the FBG, the temperature cross sensitivity can be removed. With the in-fiber laser power increase, RI of the multilayer graphene exhibits linearly increasing modulation process. The RI modulation can be deduced by the modulation efficiency of Bragg wavelength shift versus power. The modulation efficiency of different wavelength laser is slightly different, which is mainly due to the different interaction area between light field and coating graphene. The maximum modulation efficiency can get 59.3 pm/mW corresponding to 0.0545RIU (refractive index unit)/W RI modulation efficiency and 7.446 × 10?4 RI increment of the multilayer graphene.
关键词： Laser modulation,Refractive index,Graphene,Optical fiber Bragg grating
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Optical Repetition Rate Stabilization Techniques of Ultrafast Yb Doped All Fiber Oscillator
摘要： High intensity lasers usually based on OPCPA technology [1] require stable and precisely controlled repetition rate of the oscillator. Common method of repetition rate control is based on movable mirrors mounted on piezoelectric stages in free space [2]. This method has some disadvantages such as sensitivity to changes of ambient conditions and requirement for high voltage driving of piezo actuators. Different approach of fiber laser repetition rate control, which helps to overcome these shortcomings, is based on refractive index modification [3] instead of geometrical oscillator length change. In this work we demonstrate all-fiber concept of precise repetition rate control of an ultrafast ytterbium oscillator passively mode-locked using semiconductor saturable absorber mirror (SESAM). Refractive index change in Er-doped fiber core induced by pump laser power change allowed to lock repetition rate of oscillator to external clock frequency using phase-locked loop (PLL) electronics.
关键词： Refractive Index Modification,Ultrafast Yb Doped All Fiber Oscillator,Optical Repetition Rate Stabilization,Phase-Locked Loop
更新于2025-09-12 10:27:22
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Sensitivity enhancement of silicon strip waveguide ring resonator by incorporating a thin metal film
摘要： In this work, we proposed a metal-assisted silicon strip waveguide design for highly sensitive refractive index sensing applications. To prove the superiority of our proposed design, we make a fair comparison with the standard silicon strip waveguide of comparable geometry. In metal-assisted waveguide structure, a thin SiO2 layer is sandwiched between gold and silicon strip waveguide. The transmission spectrum and E-field distribution of these structures are simulated using 3D-Finite Element Method (FEM). In the first part of the paper, we demonstrated the enhancement of the evanescent field in the upper cladding region of a straight strip waveguide which makes it an ideal candidate for evanescent field gas absorption sensor. In the second part, we designed a metal-assisted silicon strip waveguide ring resonator of radius 1.5 μm and verified its higher sensitivity, Q-factor and figure of merit compared to standard ring resonator. The maximum sensitivity of 300 nm/RIU is obtained which is ~67% higher than the sensitivity of a standard ring resonator design when sandwiched SiO2 layer is equal to 50 nm in our proposed design. We believe that our study will provide new favourable circumstances to design sensors with improved sensitivity.
关键词： Metal-assisted silicon strip waveguide,refractive index sensor,ring resonator
更新于2025-09-12 10:27:22
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Research on Fabrication and Sensing Properties of Fiber-Coupled Whispering Gallery Mode Microsphere Resonator
摘要： In this paper, a fiber-coupled whispering gallery mode (WGM) microsphere resonator was fabricated with using a simple package scheme. The resonant properties of the WGM resonator are analyzed and their responses to bulk refractive index and temperature are theoretically and experimentally investigated. Experiment results show that the bulk refractive index sensitivity is about 20.49 nm/RIU with detection limit of 4.3×10-4 RIU and very low temperature sensitivity of 7.38 pm/℃. Moreover, the WGM microsphere resonator is firstly used for acoustic intensity level sensing, and the sensitivity is about -1.9 pm/dB, which can enlarge the application field of the WGM sensor and can be used for noise monitoring to enhance environmental protection.
关键词： Whispering gallery mode,Temperature sensor,Microsphere resonator,Refractive index sensor,Acoustic intensity level sensor
更新于2025-09-12 10:27:22
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Sensing characteristics of long period grating by writing directly in SMF-28 based on 800?nm femtosecond laser pulses
摘要： A long period grating is fabricated in standard SMF-28 ?bers without hydrogen loading by adopting point-by-point direct writing based on femtosecond laser pulses with 800 nm wavelength and 100 fs pulse width. Its sensing characteristics is investigated and the sensing sensitivities to temperature, external refractive index (RI) and strain are systematically examined as well. The experimental results show that the sensing sensitivity of the long period grating to temperature, RI and strain is about 124 pm/°C with a linearity of 0.989 within temperature ranging from 20 °C to 800 °C, ?582.5 nm/RIU (refractive index unit) with a linearity of 0.998 in the RI ranging from 1.342 to 1.380, and ?9.45 × 10-4 dB/με with a linearity of 0.98 in the strain ranging from 0 to 2925 με, respectively. The high sensitivity of prepared LPG will have potential application values in sensing measurement of multi-parameters and in the ?eld of high temperature and harsh environments detection.
关键词： Refractive index (RI),Long Period Gratings (LPGs),Femtosecond laser,Strain sensing,Temperature sensitivity
更新于2025-09-12 10:27:22
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Numerical study of a high negative refractive index based tunable metamaterial structure by graphene split ring resonator for far infrared frequency
摘要： We present a numerical study of a high negative effective refractive index based actively tunable squared shaped graphene split ring resonator for far infrared frequency spectrum. Graphene split ring resonator (GSRR) structure is investigated for the different cases of the split rings. Tunability of the structure is controlled by varying the different chemical potential of the graphene sheet, which can be controlled by external potential. Transmission, Reflection and Absorption parameters are investigated to check the resonance response. At each and every point of resonance, highly negative refractive index is been observed. The proposed structure is producing the multiple short as well as large band resonance band over 1 THz to 2.5 THz frequency range for the different chemical potential that varies between 0.1 eV to 0.9 eV. The study results inferred that tunable properties of the GSRR structure can help to design the various photonics device such as sensor, modulator and polarizer, etc.
关键词： Far infrared frequency,Negative refractive index,Graphene split ring resonator,Metamaterial,Tunable
更新于2025-09-12 10:27:22
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A Green Slab Waveguide for Plasmonic Sensors Based on Bacterial Cellulose
摘要： We use as optical waveguide a green composite, based on bacterial cellulose (BC). More specifically, we have sputtered a thin gold film on this innovative slab waveguide for obtaining a Localized Surface Plasmon Resonance (LSPR) sensor. Experimental results confirm the possibility of using the BC based composite as an environmental friendly optical sensor platform with plasmonic capabilities, which could be exploited for realizing disposable biosensors. The new optical sensor has been used by combining it with optical fibers. The fibers connect the green disposable optical sensor with a light source and with a spectrometer. The device has been tested by measuring the refractive index of different water-glycerin solutions.
关键词： refractive index measurement,sustainable development,localized surface plasmon resonance,bacterial cellulose,optical sensors
更新于2025-09-12 10:27:22
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Investigation of the optical properties of CuIn (Se,S)2 thin films for photovoltaic application
摘要： In this study, thin CuInSe2 and CuInS2 ternary films were successfully deposited on Indium ThinOxide (ITO) substrates by a low-cost electrochemical deposition technique.During the deposition of thin layers, the pH of the solution was maintained at 1.6, the applied potential at -0.750 V and the deposition time at 60 minutes, to control the ionic concentration of the solution; Sodium citrate has been used as a complexing agent.The morphology of the films was examined by optical microscopy, a homogeneous and without pin hole films were founded based on sulfur compared to those prepared with selenium precursor.Optical parameters such as absorbance (A), transmittance (T), band gap energy (Eg) and optical constants like refractive index (n), extinction coefficient (k) and dielectric constant (ε) were extracted using UV-Vis spectroscopy.It is remarkable that all films have a high absorption capacity and low transmittance. But there is a small difference in the results in terms of percentage (%) of the absorbance and transmittance of the films. The highest transmittance value is observed for selenium (12%) with band gap energy about 1.52 eV and for the deposited film with sulfur the lower transparency of 9% at 800 nm with band gap energy about 1.46 eV.The higher value of the refractive index (3.5) for films prepared using sulfur as a precursor is attributed to the thickness (1.99 μm) of the films andthe important value of the extinction coefficient (0.055) is observed for this precursor because of the strong absorption of this film.
关键词： Gap,Spectroscopy,Dielectric constant,CuInSe2,Refractive index,CuInS2,Thin films
更新于2025-09-12 10:27:22
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Investigating the nonlinear optical properties of poly eosin-Y phthalate solution under irradiation with low power visible CW laser light
摘要： In this work, the study of the nonlinear optical properties of poly eosin-Y phthalate solution using the diffraction ring patterns and the Z-scan methods are presented. The diffraction ring patterns were observed when a low power laser beam of wavelength of 473 nm passed through the poly eosin-Y phthalate solution. It was found that the number of rings and diameter of the outer-most ring in each pattern depends on the incident intensity of the laser beam and type of the beam wave front. The Fresnel-Kirchhoff diffraction integral theory was used to simulate the diffraction ring patterns and found good agreement with experimental results. Both diffraction ring patterns and closed aperture Z-scan techniques were used to calculate the nonlinear refractive index, while open aperture Z-scan was used to calculate the nonlinear absorption coefficient of the poly eosin-Y phthalate solution. The possibility of using the sample as an optical limiter is tested.
关键词： Nonlinear refractive index,Self-phase modulation,Optical limiting,Diffraction ring pattern,Z-scan technique,Thermal nonlinearity
更新于2025-09-12 10:27:22