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A fiber-based Fabry–Perot (FP) optical sensor is well-suited for the rapid and selective detection of gas molecules, including volatile organic compounds (VOC), explosive analytes, etc. The sensing probe of a fiber-based Fabry–Perot (FP) sensor is achieved through the deposition of a thin vapor-sensitive material on a cleaved fiber end-face, primarily using the dip-coating method. Because the sensitivity of the FP sensor is closely tied to its cavity length, it is crucial for the coating mechanism to consistently create FP cavities of the same length and thickness. The paper details a process for the controlled deposition of polymer onto an optical fiber, achieved through dip coating. The determination of the shape, size, and other properties of the polymer-based FP cavity involved a comprehensive analysis of the coating steps. Fabricated sensors were further used to evaluate the temporal progression of acetone sensing experiments in response to VOC. Taken as a whole, the outcomes outlined in this paper underscore the potential for achieving consistent coating/cavity thickness in a single-mode fiber. [ABSTRACT FROM AUTHOR]

In order to obtain the impact frequency of resonant coal breaking by self-excited oscillation pulsed supercritical carbon dioxide (SC-CO2) jet, large eddy simulation was used to analyze the formation and development process of self-excited oscillation pulsed SC-CO2 jet, the variation of jet impact frequency in the nozzle and the free flow field, and the variation of jet impact frequency at different positions in the jet axis and under different cavity lengths. The test device of jet impact frequency was developed, and experiments were performed to verify the conclusions of the numerical simulations. The results show that the frequency of the self-excited oscillation pulsed SC-CO2 jet is different in the nozzle and the free flow field. In the nozzle, the frequency generated by the fluid disturbance is the same, and the jet frequency at the exit of the nozzle is consistent with that inside the nozzle. In the free flow field, due to the compressibility of CO2, the pressure, velocity and other parameters of SC-CO2 jets have obvious fluctuation patterns. This feature causes the impact frequency of the self-excited oscillation pulsed SC-CO2 jet to decrease gradually in the axis. Changing the cavity length allows the adjustment of the jet impact frequency in the free flow field by affecting the disturbance frequency of the self-excited oscillation pulsed SC-CO2 jet inside the nozzle.

In contrast to the traditional black box machine learning model, the white box model can achieve higher prediction accuracy and accurately evaluate and explain the prediction results. Cavity water depth and cavity length of aeration facilities are predicted in this research based on Extreme Gradient Boosting (XGBoost) and a Bayesian optimization technique. The Shapley Additive Explanation (SHAP) method is then utilized to explain the prediction results. This study demonstrates how SHAP may order all features and feature interaction terms in accordance with the significance of the input features. The XGBoost–SHAP white box model can reasonably explain the prediction results of XGBoost both globally and locally and can achieve prediction accuracy comparable to the black box model. The cavity water depth and cavity length white box model developed in this study have a promising future application in the shape optimization of aeration facilities and the improvement of model experiments. HIGHLIGHTS SHAP can accurately evaluate the prediction results of XGBoost.; SHAP considers the role of both single features and interactive features.; Bayesian optimization can significantly improve XGBoost performance.; Local interpretation can visualize the impact of all features.; The cavity water depth is more complex than the cavity length.;

We demonstrate an S-shaped double-spiral microresonator (DSR) for detecting small volumes of analytes, such as liquids or gases, penetrating a microfluidic channel. Optical-ring resonators have been applied as label-free and high-sensitivity biosensors by using an evanescent field for sensing the refractive index of analytes. Enlarging the ring resonator size is a solution for amplifying the interactions between the evanescent field and biomolecules to obtain a higher refractive index sensitivity of the attached analytes. However, it requires a large platform of a hundred square millimeters, and 99% of the cavity area would not involve evanescent field sensing. In this report, we demonstrate the novel design of a Si-based S-shaped double-spiral resonator on a silicon-on-insulator substrate for which the cavity size was 41.6 µm × 88.4 µm. The proposed resonator footprint was reduced by 680 times compared to a microring resonator with the same cavity area. The fabricated resonator exposed more sensitive optical characteristics for refractive index biosensing thanks to the enhanced contact interface by a long cavity length of DSR structures. High quality factors of 1.8 × 104 were demonstrated for 1.2 mm length DSR structures, which were more than two times higher than the quality factors of microring resonators. A bulk sensitivity of 1410 nm/RIU was calculated for detecting 1 µL IPA solutions inside a 200 µm wide microchannel by using the DSR cavity, which had more than a 10-fold higher sensitivity than the sensitivity of the microring resonators. A DSR device was also used for the detection of 100 ppm acetone gas inside a closed bottle. [ABSTRACT FROM AUTHOR]

The major issue in improving the efficiency of the scramjet engine is ensuring adequate hydrogen fuel distribution within the supersonic chamber. Recently cavity floor injection strategy is a promising approach to keeping the flame stable under an extensive range of operational conditions. Thus the present investigation involves the simulation of a scramjet combustor with cavity floor H 2 injection technique under different free-stream Mach numbers using a computational approach. Our results indicate that as the free-stream Mach number rises; the circulations inside the cavity become more intense, resulting in the formation of a stable igniting zone inside the cavity. Next, the effect of different cavity floor length injection on the performance of the combustor has also been explored. The results obtained indicate an optimum cavity floor injection which can control the propagation of the shockwave in the downstream direction; or else, boundary layer separation may occur, resulting in even engine unstarts. For the present case, the optimum cavity floor length is found to be 45 mm. • Effect of different free-stream Mach number on the performance of scramjet has been explored. • Hydrogen distribution is found to be more uniform at Mach number 2.5. • Comparative evaluation of combustor is discussed by varying the cavity floor length. • Fuel injection from the cavity floor may effectively spread the H 2 within the cavity. • The optimum cavity floor length is found to be 45 mm. [ABSTRACT FROM AUTHOR]

The paper presents the results of a cavitation in a slit channel study and offers an analytical description of cavity development. Special emphasis was placed on examining partial cavitation near a NACA 0012 hydrofoil (NACA – the National Advisory Committee for Aeronautics) inside slit channels of different geometries. Experimental investigation was carried out via high-speed imaging and the laser Doppler anemometry (LDA) method. The experimental data showed that the local flow velocity in hydrofoil leading edge area increased abruptly under arising cavitation. In addition, occurrence of cavitation raised flow velocity pulsation by 20%. In the case of a shorter channel, cavity growth occurred at higher cavitation numbers than for a longer channel. The cavity growth velocity was higher for a shorter channel. We showed that the tendency of partial cavitation development in the slit channel can be described as follows: L / C ∼ σ −1, where L is the cavity length; C is the hydrofoil chord; σ is the cavitation number; and parameter A changes as the slit channel length is varied. Comparison of cavitation development near hydrofoil at different attack angles α inside the slit channel with a three-dimensional (3D) cavitation tunnel was conducted. Cavitation in the slit channel occurred at lower σ /2 α values compared to 3D cavitation flow around the hydrofoil. To directly compare lengths of the attached cavities arising in slit channels and 3D cavitation tunnels, an additional parameter is proposed, taking into account friction of the slit channel: K = λ · l / D. This parameter allowed us to quantitatively compare the characteristics of cavitating hydrofoils in slit channels and 3D tunnels. The paper provides the governing criteria of the cavitation in the slit channel. Our results propose the physical foundations for the development of cavities in the slit channel. [ABSTRACT FROM AUTHOR]

A novel method to obtain the cavity length of a Fabry-Perot interferometer (FPI) precisely based on the Vernier effect via a virtually variable reference FPI is proposed in this paper. Compared with the traditional method based on the measurement of wavelength spacing between two adjacent peaks in the spectrum of a single FPI, or enlarge the wavelength spacing with the Vernier effect by incorporating a real reference FPI in the sensor part, the present scheme is more flexible and applicable. By scanning the cavity length of the virtual reference FPI digitally, the accurate cavity length of the real FPI can be obtained when the free spectrum range (FSR) of the spectrum envelope of the combined FPIs reaches a maximum. Both theoretical analysis and experimental results show that the proposed scheme is superior to traditional methods, and with the present measurement condition, more than 20 times accuracy improvement for the determination of cavity length can be achieved.

We demonstrate an S-shaped double-spiral microresonator (DSR) for detecting small volumes of analytes, such as liquids or gases, penetrating a microfluidic channel. Optical-ring resonators have been applied as label-free and high-sensitivity biosensors by using an evanescent field for sensing the refractive index of analytes. Enlarging the ring resonator size is a solution for amplifying the interactions between the evanescent field and biomolecules to obtain a higher refractive index sensitivity of the attached analytes. However, it requires a large platform of a hundred square millimeters, and 99% of the cavity area would not involve evanescent field sensing. In this report, we demonstrate the novel design of a Si-based S-shaped double-spiral resonator on a silicon-on-insulator substrate for which the cavity size was 41.6 µm × 88.4 µm. The proposed resonator footprint was reduced by 680 times compared to a microring resonator with the same cavity area. The fabricated resonator exposed more sensitive optical characteristics for refractive index biosensing thanks to the enhanced contact interface by a long cavity length of DSR structures. High quality factors of 1.8 × 104 were demonstrated for 1.2 mm length DSR structures, which were more than two times higher than the quality factors of microring resonators. A bulk sensitivity of 1410 nm/RIU was calculated for detecting 1 µL IPA solutions inside a 200 µm wide microchannel by using the DSR cavity, which had more than a 10-fold higher sensitivity than the sensitivity of the microring resonators. A DSR device was also used for the detection of 100 ppm acetone gas inside a closed bottle.

A novel method to obtain the cavity length of a Fabry-Perot interferometer (FPI) precisely based on the Vernier effect via a virtually variable reference FPI is proposed in this paper. Compared with the traditional method based on the measurement of wavelength spacing between two adjacent peaks in the spectrum of a single FPI, or enlarge the wavelength spacing with the Vernier effect by incorporating a real reference FPI in the sensor part, the present scheme is more flexible and applicable. By scanning the cavity length of the virtual reference FPI digitally, the accurate cavity length of the real FPI can be obtained when the free spectrum range (FSR) of the spectrum envelope of the combined FPIs reaches a maximum. Both theoretical analysis and experimental results show that the proposed scheme is superior to traditional methods, and with the present measurement condition, more than 20 times accuracy improvement for the determination of cavity length can be achieved. [ABSTRACT FROM AUTHOR]

The chute aerators separate the flow from the chute bottom, and the violent turbulence is generated after the flow impacts the bottom. Although the chute aerators were widely investigated experimentally, the air concentration distribution of the lower jet in the impact zone remains to be explored systematically. In the impact zone, it is observed that a portion of the air stays in the rollers instead of traveling with the flow, decreasing the air transportation capacity. Based on extensive tests, a comprehensive formula is developed to compute the air concentration distribution in the impact zone, with results in good agreement with the model tests. [ABSTRACT FROM AUTHOR]

Stability of a bulk-optical resonator is a very important factor in the cavity analysis. The stability of a resonator depends on the properties and arrangement of the optical components, basically the curvature of reflecting surfaces, other focusing effects, and the distances between the components. When a parameter such as cavity length or the radius of curvature of the focusing element in the resonator is varied, the cavity stability also changes. This paper presents a concise and very simplified design and modeling of a 'L' shaped cavity, with reflecting and refracting elements along with two curved mirrors (cavity mirrors) using ABCD matrix and also the importance of an optical element used in L-cavity. The stability is calculated from the ABCD matrix and analyzed using cavity parameters like cavity length and radius of curvature. The stability of the L-cavity is analyzed by varying the length of the cavity from 100 mm to 1500 mm. The L-cavity is stable up to 1500 mm for mirror as intra cavity element and is stable beyond 1500 mm also for TIR (Total internal reflection) prism as intra cavity element. Similarly, the radius of curvatures of mirror and prism also varied from 100 mm to 2500 mm. The L-cavity is stable from 300 mm in mirror case and further also. The L-cavity is stable from 100 mm in TIR prism case and further also. The power distribution of laser beam is also simulated and analyzed for both mirror and TIR prism L-cavity using ZEMAX tool in non sequential mode. From the stability point and other properties of an optical element used in the L-cavity, the importance of the mirror and TIR prism is also studied and also which optical element is preferred for further ring cavity applications. • Impact of cavity length and radius of curvature on state of the stability analyzed. • L-cavity is stable up to 1500 mm for mirror and stable beyond 1500 mm for prism case. • For the mirror the power distribution is 66 W/cm2 and for the prism 97 W/cm2. • The backscattering in the prism is lower than that of the mirrors. • refracting element is the best optical intra cavity element for cavity applications. [ABSTRACT FROM AUTHOR]

Abstract We have studied the characteristics of frequency response at 850-nm GaAs high-speed vertical-cavity surface-emitting lasers (VCSELs) with different kinds of oxide aperture sizes and cavity length using the PICS3D simulation program. Using 5-μm oxide aperture sizes, the frequency response behavior can be improved from 18.4 GHz and 15.5 GHz to 21.2 GHz and 19 GHz in a maximum of 3 dB at 25 °C and 85 °C, respectively. Numerical simulation results also suggest that the frequency response performances improved from 21.2 GHz and 19 GHz to 30.5 GHz and 24.5 GHz in a maximum of 3 dB at 25 °C and 85 °C due to the reduction of cavity length from 3λ/2 to λ/2. Consequently, the high-speed VCSEL devices were fabricated on a modified structure and exhibited 50-Gb/s data rate at 85 °C.

A ridge‐waveguide (RW) directly modulated laser (DML) with a coplanar electrode structure is proposed and measured in this paper. Since utilizing the coplanar electrode can significantly reduce parasitic capacitance, the frequency responses of DMLs exhibit a quite low roll‐off. Shortening the cavity length L is attractive to enhance the high‐speed performance of DMLs, but it will increase the mirror loss and the chip resistance at the same time. We analyzed the static and dynamic characteristics of 200‐μm, 250‐μm, and 300‐μm lasers experimentally and theoretically to investigate the impact of L on the coplanar‐electrode DML. Shortening the cavity length can improve the relaxation oscillation frequency fr effectively. The 200‐μm DML achieves a bandwidth of 15.3 GHz. The fr is the most important limiting factor for the laser to obtain a wide bandwidth. Decreasing L and increasing the differential gain are promising for the further improvement of fr. However, shortening L causes a more severe thermal effect and the deterioration of the linearity. This trade‐off must be considered in the future study. [ABSTRACT FROM AUTHOR]

The authors experimentally demonstrated the generation of mode‐locked pulses from all‐fibre erbium‐doped fibre laser cavity by using organic material, Alq3, as a saturable absorber (SA). The SA film was integrated into a ring fibre laser cavity to act as a mode‐locker. A mode‐locking operation was achieved in three different experiments with pulse width/repetition rate of 1.26 ps/3.36 MHz, 970 fs/3.36 MHz and 820 fs/4.9 MHz by using cavity length/optical coupler (OC) of 61.5 m/80:20 OC, 61.5 m /95:5 OC and 42 m/80:20 OC, respectively. All the experiments produced a soliton and a very stable mode‐locking operation at central wavelength of ∼1561 nm. The experiments confirmed that organic material can readily be used as SA for a mode‐locked operation in the 1.5 μm region. This demonstration might shed new insights into the potentials and techniques for developing ultrafast fibre lasers by using organic materials as SAs. [ABSTRACT FROM AUTHOR]

A miniaturized inline Fabry-Perot interferometer fabricated by fs laser direct writing in the water has been proposed. The performances of the Fabry-Perot interferometers fabricated in the deionized water and air have been investigated and the experimental results demonstrate that the sensor made in the water has better performance. The influence of the cavity length on the sensitivity is discussed as the temperature increases from 50 °C to 500 °C. The sensor fabricated in the water can be used as a high-temperature sensor in harsh environments due to its miniaturized size, high linearity, good repeatability and perfect mechanical property. [ABSTRACT FROM AUTHOR]

The flow around the ramp embedded in a pressurized tunnel is divided into the various zones immediately downstream of the ramp, including the cavity and the main zone of flow above the shear layer. The aeration coefficient of the flow from the lower surface (inside the cavity)(βlower) is a function of non-dimensional numbers which aerator geometry parameters such as cavity length to ramp height Lc/tr is considered as one of the most important parameters. Therefore, in the present study, OpenFOAM software and RNG k-ε turbulence model were used to simulate the flow to study the aeration effect on flow characteristics, so the range of aeration coefficient as 0%<β<10% for four ramps with different tr/d ratios is Applied, then by increasing the aeration coefficient in the range of 0%<β<16%, The dependency range of relative Cavity length Lc/tr to (β) was evaluated. In order to verify performance of the numerical model, experimental results of Manafpour test were used. The results of the research indicate that in the aeration of flow with aerator ramp, the height of ramp has more influence relative to ramp angle. Moreover the main Effectiveness of the aeration coefficient on the cavity length was limited to air percent less than 10%. [ABSTRACT FROM AUTHOR]

• Provide a systematic experimental investigation of the ventilated partial cavitation (VPC) across a broad range of flow and ventilation conditions. • Reveal the presence of four distinct VPC regimes, and summarize the flow and ventilation conditions corresponding to different regimes on a VPC regime map. • Provide a clear physical explanation of the transition across different regimes based on the variation of gas leakage mechanisms. • Elucidate the ambiguities present in the current study of VPC from different research groups thorough discussion and comparison of our results with prior studies. This study presents the experimental investigation on the cavity regime and the corresponding geometric characteristic of ventilated partial cavitation (VPC). Experiments are conducted in the high-speed water tunnel at Saint Anthony Falls Laboratory. A backward-facing cavitator mounted on the ceiling of test section is used to generate the VPC. The flow filed and the dynamic motion of VPC are captured by the imaging system under varying water speeds and ventilation rates. Four distinct cavity regimes are classified, referred to as foamy cavity (FC), transition cavity (TC), open cavity (OC) and two-branch cavity (TBC). The distribution of these cavity regimes over Froude number (Fr) and ventilation coefficient (C Qs) is summarized in a regime map with FC and TBC occupying the majority portion of the map. More importantly, the C Qs − F r curves demarcating neighboring cavity regimes are revealed satisfying a clear linear relation for FC–TC and a quadratic relation for TC–OC and OC–TBC when Fr is subtracted with a constant corresponding to the inception condition of the cavity regime. Such trends are attributed to the two gas entrainment mechanisms present in VPC, referred to as recirculating vortex entrainment and cavity closure entrainment. Moreover, the geometric characteristic of VPC characterized by the cavity length is examined. With increasing ventilation at fixed Fr , the cavity length grows linearly in OC regime and remains unchanged in TBC regime. The maximum cavity length of OC is found to be within around 7 times of cavitator height. With increasing Fr at fixed ventilation, the cavity length first grows proportional to Fr 2 in TBC regime but drops sharply with a small increase of Fr when the cavity transitions from TBC to OC. At fixed Fr , the cavity underpressure rises to maximum (minimum σ C) and stays unchanged in TBC upon increasing ventilation. As a result, in TBC, the cavity length is shown to satisfy a power law relation with respect to Fr or σ C , while in OC, the cavity length is influenced by the interplay among C Qs , σ C and Fr with no clear trend observed. [ABSTRACT FROM AUTHOR]

The flow around the ramp embedded in a pressurized tunnel is divided into various zones downstream of the ramp, including the cavity and the main zone of flow above the shear layer. Ramp angle and height are parameters that affect the flow characteristics such as cavity length, velocity, and pressure coefficient immediately downstream of the ramp. In this study, OpenFOAM open source software and RNG K-ε turbulence model were used to simulate the flow around the under pressure tunnel ramp. In order to investigate the effect of the ramp geometry on the flow in various relative air discharges 0<β<10, the range of height and the angle of the ramp as 5<θ<20 and 0.1r/d<0.4 were developed and simulated. The correlation coefficient between the numerical and experimental results for the relative cavity length is in the range of 0.9377≤ R²≤ 0.9722 that indicates proper agreement between results. The result of the research shows that in both cases of fixed height of ramp and increasing ramp angle, and fixed angle of the ramp and increasing ramp height, the values of the cavity length and maximum turbulence intensity increase, and the minimum pressure values at the cavity zone bed are decreased. But in both cases, the sensitivity of the three mentioned parameters is higher than the ramp height increment. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to investigate experimentally the influence of the cavitation extent on the pressure and velocity fluctuations in a small convergent–divergent channel. The mean cavity length is determined from high-speed photography images. The mean pressure and the intensity of the pressure fluctuations are obtained from the transient pressure signals recorded by two pressure transducers at the inlet and outlet of the test section. The statistical turbulence quantities are derived from the instantaneous velocity fields measured by the laser-induced fluorescent particle image velocimetry (PIV-LIF) technique. The experimental results show that the decrease of the cavitation number (the increase in the extent of cavitation) leads to a rise in the turbulent fluctuations in the wake region due to the impact of vapour clouds collapsing, while the presence of a vapour phase is found to reduce the streamwise and cross-stream velocity fluctuations in the attached cavity. It might be attributed to two mechanisms: the presence of a vapour phase modifies the vortex-stretching process, and the cavitation compressibility damps out the turbulent fluctuations. Similar effects of cavitation are also observed in the pressure fluctuations.

We demonstrate a high-sensitivity gas pressure sensor by use of an in-fiber Fabry-Pérot interferometer (FPI) based on hollow-core photonic bandgap fiber (HC-PBF) with a side-opened channel. The FPI was constructed by splicing a thin piece of HC-PBF between two stander single-mode fibers. Then, a side-opened channel was drilled through the hollow core of the HC-PBF by use of a femtosecond laser. Such an FPI with a side-opened channel greatly enhanced the gas pressure sensitivity up to 4.24 nm/MPa, which is two orders of magnitude higher than that of FPI with an enclosed cavity. In addition, the effects of cavity length on the gas pressure sensing performance were also studied. A shorter cavity gives rise to broader measurement range while offering larger detection limit, and vice versa. The structure size is tens of micrometers, which makes it possible to develop an ultracompact high-sensitivity gas pressure sensor.

Abstract Experiments were conducted to investigate the cavity length pulsation characteristics in jet pumps with different area ratios during limited operation stage. Images of various cavitating flows were captured and analyzed to study the cavity length pulsation characteristics by high speed camera technology. It was found that the development tendency of time-averaged cavity length can be divided into two sections with different pulsation intensity by throat length. Further analysis indicated that the time-averaged cavity length is a function of area ratio and outlet pressure ratio independent of the inlet pressure. And the time-averaged cavity length decreases slowly and then faster with the increase of comprehensive parameters. Meanwhile, the cavity length pulsation can be decomposed into low frequency component and high frequency component. The pulsation intensity of low frequency component is relatively high during unstable limited operation stage, while it is at a low level during stable limited operation stage. Besides, smaller area ratio and inlet pressure result in larger pulsation intensity of low frequency component during unstable limited operation stage. The experimental points of high frequency component pulsation intensity collapsed around a V-shaped curve and it reached the minimum value when time-averaged cavity length is approximate to the throat length. Highlights • The development tendency of cavity length of jet pumps with different area ratio during limited operation stage is studied. • The relationship between time-averaged cavity length, flow parameter and area ratio is discussed. • The cavity length pulsation of jet pumps during limited operation stage is distinguished. • The dominant frequency distribution of cavity length pulsation is discussed. • The influence of area ratio and inlet pressure on the cavity length pulsation intensity is illustrated. [ABSTRACT FROM AUTHOR]

Utilizing the principles of intracavity absorption spectroscopy, a biomedical sensor has been developed. The unique feature is the deployment of dual-mode competition which renders characteristics of feasibility, cost, and investigation in various domains. Insight of the high sensitivity of this sensor, relative intensity noise (RIN) is being explored as one of the detection parameters. Cavity length and mode spacing effects of the sensor on average RIN have been investigated to optimize these parameters for improvement in RIN response of the sensor. It has been found that operating the sensor for increased mode spacing improves its RIN response by 24%. In this mode of operation, change in cavity length has almost negligible effect on RIN response of the sensor. This fact in the proposed sensor system can be used to detect various trace gases with minute concentration levels thereby revealing important information about specific diseases in human body. [ABSTRACT FROM PUBLISHER]

In this paper, the three dimensional ventilated cavitating flow in the steady condition around a projectile model is simulated using CFD method combined with a sst k-ω turbulence model and volume-of-fluid technique, With the aid of CFD software ANSYS CFX. The numerical model is validated using comparisons between numerical predictions and existing experimental data and fairly good agreement is revealed. The numerical results show that with increasing the ventilation gas rate at constant Froude number, the cavity length gradually increases to a critical value and then remains fixed upon further increase in gas ventilation rate. Also, it has been observed that rear portion of larger cavity moves upwards due to gravitational effect. With increasing the ventilation gas rate, the gas leakage mechanism at rear portion of ventilated supercavity changes from the re-entrant jet closure mode to twin vortex closure mode. The variation of ventilation gas rate versus cavity length is a function of Froude number and the critical ventilation gas rate increases linearly with Froude number. [ABSTRACT FROM AUTHOR]

These days, organic light-emitting diodes (OLEDs) have become the mainstream displays in the mobile markets and on the verge of penetrating in the automobile vehicle display sector on large scale. The major problem in such long-lasting display products is the blue device lifetime and efficiency. To overcome these issues, a blue tandem top emission architecture with a strong micro-cavity effect can become the just legitimate candidate. In this study, we have investigated optical performances of fabricated blue tandem top emission OLED (TEOLED) device by comparing the results of two optical simulation methods. Electroluminescent spectra variation, front side efficiency increase ratio, and viewing angle characteristics are compared with the single stack blue TEOLED device results. The calculated front efficiency value by optical simulation for 2 and 3-tandem TEOLED devices were found to be 1.82- and 2.32-times higher than the single stack blue TEOLED device. The experimentally obtained values of 2 and 3-tandem TEOLED devices showed at 1.75 and 2.31, respectively, and are in good agreement with the calculated values. We suggest that the fabricated tandem blue TEOLEDs are suitable for automotive display applications. [Display omitted] • Optical property evaluation of blue tandem top emission OLED (TEOLED) device. • Comparison between the experimental and optical simulation results. • To predict the efficiency accurately by optical simulation, Purcell effect should be considered. • The 2 and 3-tandem TEOLED devices have about 1.75 and 2.31 times higher efficiency than single TEOLED device, respectively. [ABSTRACT FROM AUTHOR]