Refractive Index Difference Research Articles

Effect of Gd3+/Nd3+- dual doped borate glasses on the physical and spectroscopic properties for the NIR emission at 1.069 µm

Near-infrared luminescence properties of dual doped Gd3+/Nd3+-incorporated glasses were manufactured using the melt-quenching technique and characterized by several techniques. The modification in glass structure may be seen in the differences in density, molar volume, and refractive index that occur when the amount of lanthanide oxide in the glass increases. The spectroscopic properties of Nd3+ in these glasses are quite well understood, and the observed optical characteristics may be used to process and eventually determine laser properties. According to the results of XANES, the Nd oxidation state remains the predominant peak for Nd3+ in all of the samples. The transition from 4I9/2 to 4G5/2 +2G7/2 is important for the strongest band in the absorption spectra, which can be seen at 584 nm. The luminescence spectra show peaks caused by 4F3/2→4IJ (J=11/2, 13/2) at three excitation wavelengths of 526, 574 and 805 nm. After the processing, we created glass samples for the study of photoluminescence with various amounts of Nd2O3 incorporated into the best host, 25Li2O-5Al2O3-2.5Gd2O3-(67.5-X)B2O3-XNd2O3. Based on luminescence intensity, it is determined that 1.0 mol% of Nd2O3 is the concentration quenching in the studied glasses. The 4F3/2 →4I11/2 transition at 1069 nm, excited by 526, 578 and 803 nm, has the highest emission intensity. The combined findings of the glasses demonstrate that near-infrared luminescence may be successfully used with them. All of the analysis shows that the dual doped Gd3+/Nd3+ borate glass would be a potential solid-state laser candidate.

Determination of refractive index increments of PMMA particles dispersed in liquid phase

The refractive index increments of poly(methyl methacrylate) (PMMA) particles with sizes ranging from submicron to several microns were determined by measuring different concentrations of the solution and using a refractometer and microbalance calibrated by accurate traceability source. Conventionally, it was common to measure only the difference in refractive index between solvent and solution using a Bryce-type cell system, but it is difficult to perform traceable calibration since there is no reference material for refractive index increment. In this paper, we accurately quantify the refractive index increment by making individual measurements of the solvent and solution refractive indices, respectively, using Abbe-type refractometer. In addition, an uncertainty analysis was performed, and the results clarified the main factor of the variance in the refractive index increment measurements. The most important factor of variation of refractive index increment measurement is the measured apparent values at dilute concentration region including fluctuation of the system. This method was able to be applied to the determination of water content existing in particles. The percentage of the water content was determined using two different solvents, and the water content values were in good agreement within their uncertainties.

Twisted Silica Few-Mode Hollow GeO2-Doped Ring-Core Microstructured Optical Fiber

This work presents the first instance of a silica few-mode microstructured optical fiber (MOF) being successfully fabricated with a hollow GeO2-doped ring core and by strongly inducing twisting up to 790 revolutions per meter. Some technological issues that occurred during the manufacturing of the GeO2-doped supporting elements for the large hollow cores are also described, which complicated the spinning of the MOFs discussed above. We also provide the results of the tests performed for the pilot samples—designed and manufactured using the untwisted and twisted MOFs described above—which were characterized by an outer diameter of 65 µm, a hollow ring core with an inner diameter of 30.5 µm, under a wall thickness of 1.7 µm, and a refractive index difference of Δn = 0.030. Moreover, their geometrical parameters, basic transmission characteristics, and the measurements of the far-field laser beam profile patterns are also provided.

Refractive index sensing of human blood using patterned photonic crystal containing defects

This work presents an innovative platform of a multi-channel one-dimensional photonic crystal (1-DPC) based on blood refractive index data of different patients in the aspect of the main protein components like hemoglobin. This photonic crystal (PC) contains a defect center infiltrated with plasma using a microorder size syringe. When binary silica and III–V semiconductor (InSb) materials are combined, they increase the refractive index difference between the alternate layers of the composite material, resulting in a wide photonic band gap (PBG). We use the well-known transfer matrix method (TMM) to observe the reflectance of various blood samples that were previously published. We assess and contrast the influence of different refractive index data on the dynamic shift in PBG calculation for novel superior and resourceful sensor in the prevention of microscopic organisms such as SARS-CoV-2, the virus linked with COVID-19. Yet, the performance of this PC has more moral content and unlimited casting efficacy in the face of an incurable virus.

Structural, optical and dielectric properties of nanostructured La1−xSrxMnO3 perovskites

In this study, a series of nanocrystalline perovskites, La1−xSrxMnO3 (x = 0, 0.3, 0.5, 0.7), were synthesized via the combustion method, utilizing citric acid as fuel, which is an inexpensive synthesis method compared to the vacuum methods for growth. The powder X-ray diffraction study confirms the formation of the desired compositions. The XRD pattern shows that as the Sr doping concentration increases, crystallite size decreases from 30 nm to 14 nm. SEM micrographs reveal the spongy, porous structure of the prepared samples. A good optical absorbance is present in the UV and higher wavelength regions. The optical bandgap energy was increased from 1.4 eV to 2.5 eV. The concentration of Sr2+ ions can be correlated with the differences in refractive index, high frequency dielectric constant, and static dielectric constant. The BDS scrutiny of the specimens discloses that La0.3Sr0.7MnO3 harbours a prodigious dielectric constant at ambient temperature and subsonic frequencies. The dissemination of dielectric constants within the realm of low-frequency regions is elucidated in the context of the Maxwell-Wagner model. According to the results of the dielectric analysis, the dielectric constant exhibits a decrease as frequency increases, while it shows an increase with an increase in Sr doping concentration. The conductivity scrutiny lucidly expounds Johnscher's universal power law in the realm of the high-frequency region, and from the log σ – log f plot, the discernible effects of electrode polarization become manifest. Moreover, the presence of Sr ions enhances the ac conductivity.

Generating dual-wavelength VECSEL by selecting birefringence filter material and the application toward mid-infrared region via intracavity OPO.

A method for realizing a synchronized watt-level dual-wavelength vertical-external-cavity surface-emitting-laser (VECSEL) by using a tilted birefringence filter (BRF) is demonstrated. It is verified that by selecting suitable BRF material with different refractive index differences between extraordinary wave and ordinary wave, the dual-wavelength emission with a free spectrum range from sub-THz to tens of THz can be achieved. The output characteristics of such a dual-wavelength VECSEL are thoroughly investigated including its wavelength tunability and power difference. Finally, the intracavity optical parametric oscillator is applied to efficiently convert the dual-wavelength laser toward the mid-infrared region. The gain competition and longitudinal mode hopping performances for the multi-wavelength mid-infrared output are explored.

Set of mathematical models for Bessel-Gauss beams coupling into the parabolic-index fiber under the influence of atmospheric turbulence and random jitter.

The expression of efficiency for Bessel-Gauss (BG) beams coupling into the parabolic fibers (PF) after passing through the Cassegrain antenna system is first derived. The effects of atmospheric turbulence and random jitter of the coupling lens on the efficiency are also taken into account to improve the practical applicability of our model. This article use a BG beam with a wavelength of 1550 mm and fiber with a core radius RF of 50 μm and a relative refractive index difference ζ of 0.01 for simulation testing. The optimal parameters of the antenna system are determined: the radius of the primary mirror and the secondary mirror is 8.33 cm and 1.25 cm, respectively. The coupling efficiency of BG beams of different orders reaches above 94% simultaneously when the lens's focal length is 7.8 cm. After taking into account the transmission efficiency of the antenna system, the system's total efficiency for BG beams of different orders averages 76.33%, when the transmission distance is 1 km. The results show that the same degree of turbulence and random jitter have different influences on the coupling efficiency of BG beams of different orders, and lower-order BG beams have better resistance to turbulence and jitter during propagation and coupling. Moreover, the effect of the guided mode field on the coupling efficiency and the resistance to turbulence varies for different values of mode radial index in the fiber p. The guided mode with p = 0 not only enables the BG beams of different orders to achieve the highest transmission efficiency in the coupling system almost simultaneously but also the random jitter and turbulence have less influence on the coupling efficiency of this mode. It means that the BG beams can have higher efficiency when coupled to the mode with p = 0 after long-distance transmission. This property of the fiber mode at p = 0 provides conditions for the simultaneous propagation of multiple BG beams in a parabolic fiber, which provides a theoretical basis for higher transmission capacity. This research work provides a theoretical model for the theoretical study of vortex beams and optical communication, which is beneficial for the design and application of vortex beams and has instructive meaning for practical engineering design.

NIR enhancement induced by refractive index differences between noble metal particles and nanocrystals in glass-ceramics

The use of optically active ions doped into photonic media containing noble metals is an intriguing area of photoluminescence (PL) research. In this paper, we present a new approach using nickel ions doped into photonic glass ceramics (GCs) containing Au metal NCs. We exploit the unique PL properties of Ni2+ embedded in ZnAl2O4 nanocrystals (NCs). Under the same conditions, the Au-ZAO duplex samples exhibit 2–3 times higher near-infrared (NIR) emission intensity and higher absorption intensity compared to the samples without Au metal. We provide direct evidence of energy harvesting around NCs through numerical simulations. The significant NIR PL properties of Ni2+ in Au-ZAO GCs can be explained by the significant dielectric coefficient difference between the Au metal, the surrounding medium, and the ZAO NCs. Furthermore, the intense and broad emission spectra of our samples cover the entire second biological NIR region, which makes them particularly useful for biomedical applications.

Method for the refractive index of various tissues based on fluorescence microscopy

Refractive index is an important optical constant that characterizes the interaction between light and specimen. A difference in refractive index between specimen and immersion medium introduces the imaging aberration and leads to a problem that the direct thickness measurement of a specimen by optical microscopy is not accurate. However, this aberration correction still requires the exact information of the refractive index of specimen and immersion medium. Herein, we propose an imaging strategy to estimate the refractive index for an unknown specimen. A simplified diffraction model is generated to obtain the relationship between axial scaling factor and refractive index. Then regular fluorescence microscopy is performed to measure the actual axial scaling factors of specimens from mouse muscle and tumor xenograft. Referring to our theoretical plot of axial scaling factor versus refractive index, the refractive index of tissue specimen is determined. For example, we obtain a mean refractive index (n) value of 1.36 for normal muscle tissues, and 1.41 for tumor xenografts. We demonstrate that this diffraction model-based estimation method is an alternative to the current techniques, improving the accurate measurement for refractive index of tissue specimen. The simple instrument requirement with an easy specimen preparation for this estimation method of refractive index may increase the image quality on tissue specimens with less aberration.

Development of High‐Reflectivity and Antireflection Dielectric Multilayer Mirrors for AlGaN‐Based Ultraviolet‐B Laser Diodes and their Device Applications

Fabrication techniques for high‐reflectivity (HR) and antireflection (AR) dielectric multilayer mirrors for AlGaN‐based ultraviolet‐B (UV‐B) laser diodes are developed. After depositing several dielectric materials and evaluating their complex refractive indices via ellipsometry, it is determined that SiO2 as a low‐refractive‐index material and Ta2O5 as a high‐refractive‐index material are appropriate material combinations in the UV‐B region at a light wavelength of ≈300 nm due to their low extinction coefficients and large refractive index difference. Based on these results, HR mirror with a reflectance of >99% in the UV‐B region at a center wavelength of 310 nm and an AR mirror with a reflectance of ≈8% in the same wavelength range are demonstrated; a mirror with reflectance that is almost equal to the designed value is demonstrated. Furthermore, these mirrors are coated on the respective edge surfaces of the UV‐B laser diodes. A comparison of the characteristics of the same device before and after edge coating reveals a reduction in the threshold current density of laser oscillation, whereas, simultaneously, an increase in slope efficiency and external differential quantum efficiency is observed. The improvement of these device characteristics, estimated from the above reflectance values, is confirmed to be almost theoretically explainable.

Anderson localization of electromagnetic waves in three dimensions

Anderson localization is a halt of diffusive wave propagation in disordered systems. Despite extensive studies over the past 40 years, Anderson localization of light in three dimensions has remained elusive, leading to the question of its very existence. Recent advances have enabled finite-difference time-domain calculations to be sped up by orders of magnitude, allowing us to conduct brute-force numerical simulations of light transport in fully disordered three-dimensional systems with unprecedented dimension and refractive index difference. We show numerically three-dimensional localization of vector electromagnetic waves in random aggregates of overlapping metallic spheres, in sharp contrast to the absence of localization for dielectric spheres with a refractive index up to 10 in air. Our work opens a wide range of avenues in both fundamental research related to Anderson localization and potential applications using three-dimensional localized light. Whether Anderson localization of light can be achieved in three dimensions has remained an open question. Numerical calculations now show that it is possible with a random arrangement of metallic spheres, but not with dielectric ones.

Optimizing graded-index few-mode fiber for space division multiplexing.

We investigate the graded-index few-mode fiber (GI-FMF) to realize a 4-LP-mode (i.e. LP01, LP11, LP21, and LP02) fiber for mode-division-multiplexed transmission. This study optimizes the GI-FMF for both, first, for large effective indices differences (Δneff), and second, for low differential mode delay (DMD) between any two LP modes, for different optimized parameters. Thus, it shows that GI-FMF is suitable for both weakly-coupled few-mode fiber (WC-FMF) as well as strongly-coupled few-mode fiber (SC-FMF) via adjusting the profile parameter (α), refractive index difference between core and cladding (nco - nclad), and core radius (a). We report the optimized parameters for WC-GI-FMF with large effective indices difference (Δneff) of 0.6 × 10-3 and low |DMD| of 5.4 ns/km while the minimum effective mode area (Min.|Aeff|) is 80 µm2 and bending loss (BL) of the highest order mode is 0.005 dB/turn (much lower than 10 dB/turn) at a 10 mm bend radius. Here, we could break down the degeneracy between LP21 and LP02 mode, which remains a challenging task in GI-FMF. To the best of our knowledge, this is the lowest DMD (5.4 ns/km) ever reported for such a weakly-coupled (Δneff = 0.6 × 10-3) 4-LP-mode FMF. Similarly, we optimized the parameters for SC-GI-FMF with Δneff of 0.1 × 10-3 and the lowest DMD of 0.9 ns/km while Min.|Aeff| is ≫ 100 µm2 and BL of higher order mode is 6 dB/turn (< 10 dB/turn) at 10 mm bend radius. Further, we investigate narrow air trench-assisted SC-GI-FMF to reduce the DMD and achieve the lowest DMD of 16 ps/km for a 4-LP-mode GI-FMF with a minimum Δneff of 0.7 × 10-5.

Compact single fiber optical tweezer–micropipette system for completely noninvasive cell sorting

Bridging optical tweezers and microfluidics can form a multifunctional platform, which can overcome the difficulties of precise manipulation in hydrodynamic flow in a noninvasive method. However, when integrated into a microfluidic chip, the fiber optic tweezer loses its flexibility. Here, we propose a compact single fiber optical tweezer–micropipette system. It can sort particles by differences in shape and refractive index in a completely noninvasive way while retaining the flexibility, high selectivity, and precision of a fiber optical tweezer. Compact microfluidic channels are formed by combining two different-diameter micropipettes. The internal diameter of the circular microfluidic channel is less than 30 μm. Furthermore, we calculated the trapping and pushing regions of Yeast and Chlorella and achieved the separation of Yeast from Chlorella in the experiments. We did 90 sets of tests on the sorting accuracy of single fiber optical tweezer (SFOT). SFOT was able to distinguish between two types of particles in each test. With the advantages of high selectivity, high accuracy, low optical power consumption, and compact structure, such methods can be used in the fields of optical separation, cell transportation, cell sorting, and single-cell analysis.

Few-mode erbium-doped fiber with trench and weak coupling for mode gain equalization based on layered-doping technology.

A few-mode erbium-doped fiber (FM-EDF) with a step refractive index and trench structure is designed and proposed to realize the modal gain equalization of a few-mode erbium-doped fiber amplifier (FM-EDFA). The layered-doping technology is used to reduce the mode gain difference (DMG). The doping radius and doping concentration are adjusted to obtain the optimum FM-EDF structure. When the designed FM-EDF is applied to the FM-EDFA, the DMG of the whole C-band is less than 0.15dB and the DMG is less than 0.12dB at 1550nm. The minimum refractive index difference (Δ n eff) between modes can be calculated according to the refractive index and radius of the fiber core; i.e.,1.35×10-3, which will greatly reduce the coupling between modes in a practical application. Tolerances in the fiber manufacturing process are also considered for reliable FM-EDFA performance. When the doping radius and concentration of each doping layer fluctuate by ±15% based on the precise value, the maximum DMG increases to 1.8dB. In general, DMG can maintain a small value, which is beneficial for application in optical communications systems.

P‐112: Improvement of White OLED Performance by Optical Enhancement Structure

According to the demand of image quality improvement, the color gamut standard has been adjusted from DCI‐P3 to BT.2020. At present, the color gamut of some QD products can reach 80%~90%, while that of white OLED products is only about 75%. In this paper, the composite film with SiO2/SiNX distributed Bragg resonator (DBR) structure is designed and studied. The results show that the film can form a strong microcavity structure with simultaneous enhancement of RGB for white OLED devices, which overcomes the bottleneck that the strong microcavity structure can't be used in white OLED devices. It can effectively improve the performance of OLED devices, and at the same time, it has the water vapor barrier effect. It can realize the integration of multiple effects such as high color gamut, low power consumption and reliability improvement in product applications. Using the refractive index difference of SiO2/SiNx thin film, the DBR structure was fabricated by carefully designing the thickness. Based on this DBR structure, a white OLED device is fabricated. The external quantum efficiency of the device is improved, and the color gamut is up to 85% ( BT.2020), which is 11.2% higher than that of the device without DBR structure. Compared with the device without DBR structure, it has reached the QD display level, and the white light power consumption is reduced by 34.1%, HDR power consumption is reduced by 20.3%, and the overall performance is greatly improved. It provides technical support for products with high color gamut, low power consumption and long life.

Chromatic dispersion of soft contact lens materials

PurposeTo investigate and evaluate the chromatic dispersion of various hydrogel and silicon hydrogel contact lens materials. MethodsEighteen different soft contact lens materials with high and low water content in lens power of −1.00 DS were measured by one operator at temperature of 20 °C ± 0.5° soaked in ISO standard phosphate-buffered saline (PBS) and in their respective packaging solutions (PS). An analogue Abbe refractometer (Model Zuzi 320, AUXILAB, S.L., Navarra, Spain) was used for refractive index (RI) measurements at 5 different wavelengths. All contact lenses were presented in a random and masked order to the operator. The Bland-Altman method with 95 % limits of agreement (LoA) and coefficient of repeatability (CoR) was used to characterise the repeatability of refractive index measurements. The Abbe numbers for each material were calculated by entering the measured and interpolated refractive indices into the Abbe number equation. One-way ANOVA analysis was used to test if there were significant differences between the 5 different wavelengths (470 nm–680 nm) within each material. An unpaired t-test was used to determine if there were differences in refractive index or dispersion between packaging solution and PBS results. ResultsNelfilcon A (Dailies Aqua Comfort Plus) soaked in PS showed the best repeatability of all 18 examined soft contact lenses across all wavelengths with an average refractive index of 1.3848 for all 6 contact lenses with a standard deviation of 0.00064. The 95 % limits of agreement were between 1.3835 and 1.3860. The mean coefficient of repeatability for nelfilcon A was 0.00125. For contact lenses soaked in ISO Standard PBS comfilcon A (Biofinity) had the best repeatability. The average refractive index of all 6 contact lenses was 1.4041 with a standard deviation of 0.00031 and a coefficient of repeatability of 0.00060. The 95 % limits of agreement were between 1.4035 and 1.4047. The analysis with One-way ANOVA with multiple comparisons involving Holm-Sidak post-hoc, showed that there are significant differences (p < 0.001, Fratio = 376.2 between wavelengths and Fratio = 1559 between different refractive indices) in the refractive index of most common lens materials across the visible wavelength range. Based on unpaired t-test, there is no significant difference (p > 0.05) in the Abbe numbers of the tested lens materials whether they have been placed in the packaging solution or in standard PBS (p > 0.05, 95 % CI = −4.8070 to 5.8680, t = 0.2054). The Abbe numbers for the calculated contact lenses soaked in PS ranged between 43.7 and 89.9. For contact lenses stored in PBS the range was between 46.3 and 81.6. ConclusionThere is a good repeatability between repeated RI measurements taken from the same lens and from the same material. The significant differences between the refractive indices across the 5 different wavelengths showed the presence of chromatic dispersion in the 18 evaluated soft contact lens materials. Furthermore, it could be shown that there is no significant difference in dispersion whether the contact lenses are soaked in standard PBS or in their respective packaging solutions. With no other published data available as a reference, absolute accuracy of the calculated Abbe numbers remains to be confirmed, however, this study did confirm that significant chromatic dispersion exists in soft contact lens materials.

Effect of polystyrene addition on properties of porous Si3N4 ceramics fabricated by digital light processing

Porous Si3N4 ceramics with high strength and high transmittance have been widely used in the field of defense and military. Additive manufacturing (AM) technology is one of the effective means to fabricate porous Si3N4 ceramics. Nevertheless, it is difficult to prepare porous Si3N4 ceramics by using digital light processing (DLP) because of the large refractive index difference between Si3N4 powders and photosensitive resin. In this study, the effects of the amount of polystyrene (PS) powders on the properties of Si3N4 ceramic slurries and sintered ceramics were systematically discussed. The addition of PS reduced the overall refractive index of powders and increased the average particle size of powders, thus improving the cure depth of Si3N4 ceramic slurries from 11.0 ± 2.0 μm to 55.7 ± 1.8 μm. With the increase of PS content, the shrinkage and porosity of Si3N4 ceramics gradually increased, and the bulk density and flexural strength showed the opposite trend. The slurry with low viscosity (2.38 Pa٠s at a shear rate of 30 s−1) and high cure depth (51.2 ± 4.6 μm) was obtained when the content of PS was 15 wt%, which met the thickness requirements for printing. The total porosity of Si3N4 ceramics reached the maximum values at 28.21 ± 2.58%. The addition of PS solved the problem of low cure depth of slurries, and PS as a pore-forming agent could help Si3N4 ceramics form porous structure. This research provides valuable insights into the fabrication of non-oxide ceramics with high refractive index using DLP technology.

Confocal Laser Scanning Microscope Imaging of Custom-Made Multi-Cylinder Phantoms: Theory and Experiment

In this work, the image formation in a confocal laser scanning microscope (CLSM) is investigated for custom-made multi-cylinder phantoms. The cylinder structures were fabricated using 3D direct laser writing and consist of parallel cylinders with radii of 5 and 10 μm for the respective multi-cylinder phantom, with overall dimensions of about 200×200×200 μm3. Measurements were performed for different refractive index differences and by varying other parameters of the measurement system, such as pinhole size or numerical aperture (NA). For theoretical comparison, the confocal setup was implemented in an in-house developed tetrahedron-based and GPU-accelerated Monte Carlo (MC) software. The simulation results for a cylindrical single scatterer were first compared with the analytical solution of Maxwell’s equations in two dimensions for prior validation. Subsequently, the more complex multi-cylinder structures were simulated using the MC software and compared with the experimental results. For the largest refractive index difference, i.e., air as the surrounding medium, the simulated and measured data show a high degree of agreement, with all the key features of the CLSM image being reproduced by the simulation. Even with a significant reduction in the refractive index difference by the use of immersion oil to values as low as 0.005, a good agreement between simulation and measurement was observed, particularly with respect to the increase in penetration depth.

High light extraction performance using evanescent waves for top emission OLED applications with thin film encapsulation.

We report high light extraction from the top emission OLED (TEOLED) device structure by improving mainly the waveguide mode loss in the atomic layer deposition processed thin film encapsulation (TFE) layer. A novel structure incorporating the light extraction concept using evanescent waves and the hermetic encapsulation of a TEOLED device is presented here. When the TEOLED device is fabricated using the TFE layer, a substantial amount of generated light is trapped inside the device due to the difference in refractive index (RI) between the capping layer (CPL) and the aluminum oxide (Al2O3) layer. By inserting a low RI layer at the interface between the CPL and Al2O3, the direction of the internal reflected light is changed by the evanescent waves. The high light extraction with the low RI layer is attributed to the presence of evanescent waves and an electric field in the low RI layer. The novel fabricated TFE structure, CPL/ low RI layer/ Al2O3/ polymer/ Al2O3, is reported here. The current efficiency of the fabricated blue TEOLED device using this low RI layer is improved by about 23% and the blue index value is enhanced by about 26%. This new approach for light extraction will be applicable to future encapsulation technology for flexible optoelectronic devices.

Hierarchically structural TiO2-PVDF fiber film with particle-enhanced spectral performance for radiative sky cooling

Radiative sky cooling is a passive cooling method without consuming any additional energy. Here, we propose a kind of hierarchically structural and particle-enhanced TiO2-PVDF fiber film as the radiative sky cooling material. TiO2-PVDF fibers are prepared by the polymer assisted electrospinning technique. The hierarchical structure encompasses polymer fibers, inorganic enhanced particles and pores formed by interlacing fibers. In this work, the effect of TiO2 adding on the morphology, structure and spectral performance of hierarchically structural fiber film are discussed. By introducing the inorganic TiO2 particles with high refractive index into polymer fiber matrix, the refractive index difference among the hierarchical structure can increase the scattering and solar reflectance, and phonon polariton resonance will increase the infrared emission. The obtained TiO2-PVDF fiber film possesses the optimal high solar reflectivity of 99.01% (Vis band), 97.20% (NIR band) and infrared emissivity of 89.91% within the atmospheric window band. In outdoor testing in Wuhan (temperate climate) during October, the maximum sub-ambient cooling temperature under sunlight can reach 6.9℃, and 4.4℃ at night. Thus, this TiO2-PVDF fiber film can become a promising all-day cooling and energy saving material. Furthermore, it can be used in the more cooling and thermal management fields to greatly improve the comfortability of people's living and life.