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Opto-electronic platform tracking control of multi-rotor unmanned aerial vehicles based on composite disturbance compensation
摘要： Airborne opto-electronic platforms are very important in unmanned aerial vehicle systems. The stability and tracking performance of airborne opto-electronic platforms are easily affected by disturbance factors, making compensating for those disturbances a very prominent issue. In this paper, compared to the traditional disturbance observer, an improved velocity signal based disturbance observer (IVDOB) is particularly designed to compensate for the disturbance. Then its capability, robustness, and stability are discussed. For improving the stabilization accuracy and tracking performance of airborne opto-electronic platforms, the universal approximation property of fuzzy systems is used to compensate the disturbance further and an adaptive fuzzy control system based on IVDOBs is proposed. To validate the scheme, a series of experiments were carried out. The results show that the proposed control scheme can achieve reliable control precision and satisfy the requirements of airborne opto-electronic platform tasks.
关键词： Multi-rotor unmanned aerial vehicle,airborne opto-electronic platform,composite disturbance compensation,disturbance observer,approximation property
更新于2025-09-23 15:22:29
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[IEEE 2019 International Workshop on Fiber Optics in Access Networks (FOAN) - Sarajevo, Bosnia and Herzegovina (2019.9.2-2019.9.4)] 2019 International Workshop on Fiber Optics in Access Networks (FOAN) - Single-Loop Opto-electronic Oscillator at 10.4 GHz with a cascaded Microstrip Bandpass Filter Configuration
摘要： The opto-electronic oscillator is a well-known microwave photonic device that produces high-frequency signals in the microwave range. One of the main advantages of the opto-electronic oscillator is that it produces high-frequency signals with low phase noise thanks to the resonator’s properties. In most cases the opto-electronic oscillator faces the problem of generating side modes besides the oscillation signal due to non-ideal filtering. In this paper we propose a solution for the additional suppression of these undesired harmonics using a combination of two slightly detuned bandpass microstrip filters. We report an improvement for the side-mode suppression ratio about 8.3 dB with a single-loop 90-m-long opto-electronic oscillator at 10.4 GHz.
关键词： electrical bandpass filter,side-mode suppression ratio,cascaded filter connection,side modes,opto-electronic oscillator
更新于2025-09-23 15:21:01
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Tuning the optoelectronic properties of Benzo Thiophene (BT-CIC) based Non-Fullerene Acceptor Organic Solar Cell
摘要： Organic solar cells have become a center of attention in the field of research and technology due to its remarkable features. In current research work, we designed Benzo Thiophene (BT-CIC) based non-fullerene acceptor organic solar cell having A-D-A novel structure. The designed structures D1-D4 were derived from BT-CIC (non-fullerene acceptor) by replacing 2-(5,6-dichloro-2-methylene-3-oxo-2,3-dihydro-1H-inden-1-ylidene)acetonitrile of reference molecule R with different electron withdrawing end-capper acceptor moieties. The e?ect of end acceptor groups on absorption, energy level, charge transport, morphology, and photovoltaic properties of the designed molecules (D1-D4) were investigated by TD-DFT B3LYP/6-31G basic level of theory and compared with reference molecule R. Among all novel structures, D3 exhibited maximum absorption (λmax) of 701.7nm and 755.2 nm in gaseous state and chloroform respectively. The red shift in D3 was due presence of strong electron withdrawing acceptor moiety and more extended conjugation as compared to other structures. D3 also displayed lowest values of energy band gap (1.97 eV), λe (0.0063 eV) and λh (0.0099 eV) and which signify its ease electron mobility. Lowest value of binding energy 1.20 eV of D3 suggested that this molecule could be easily dissociated into charge carriers TDM results revealed that easy exciton dissociation occurred in D3. Overall, designed structure D3 was found to be more effective and efficient acceptor molecule for SMOSCs. The findings provide novel information for the development of non-fullerene acceptors for OPVs.
关键词： theoretical studies,opto-electronic properties,benzothiophene,organic solar cells,Non-Fullerene Acceptor
更新于2025-09-23 15:19:57
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Asymmetric Response Opto-Electronic Device Based on Femtosecond- Laser-Irradiated Perovskite
摘要： We have explored an asymmetric opto-electronic response of FormamidinePb(I0.8Br0.2)3 perovskite device irradiated by a femtosecond (fs) laser at different laser fluence values. Photoluminescence (PL) spectra indicated a blue shift from 772 nm (1.606 eV) to 745 nm (1.664 eV) and more than 80% quenching of the irradiated perovskite. The blue shift of the PL spectra can be attributed to compositional variation, which was confirmed through elemental analysis and X-ray diffraction. Two distinct characteristic time constants ranging from 193-46 ps and 1.9-0.61 ns were obtained by using fs transient absorption spectroscopy. The fast one represents recombination at the interface, whereas the slow one represents band-to-band recombination in the interior of the grain. Interestingly, after the perovskite was irradiated by femtosecond laser with appropriate laser fluence (0.135 J/cm2), an asymmetric I-V characteristic was achieved, which should be resulted from irreversible electric domain deflection. Due to the electron-phonon scattering induced by defect, the degree of asymmetry was sensitive to illumination power. As the photosensitive asymmetric I-V characteristics have a bearing on its photo-electric properties, the findings would be of value in photodiode, memories and other photo-electric devices.
关键词： asymmetric response,femtosecond laser,opto-electronic device,perovskite,blue shift
更新于2025-09-23 15:19:57
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Optoelectronic Properties of Electron Beam-Deposited NiOx Thin Films for Solar Cell Application
摘要： The fabrication of highly efficient nickel oxide (NiOx) thin film for optoelectronic devices is a challenging task because optoelectronic properties are considerably influenced by deposition technique and film thickness. The effect of thickness on the film properties of electron beam–physical vapour-deposited NiOx thin film has been investigated in this work. The influence of post-annealing treatment on the optoelectronic properties of the film was compared with that of the as-deposited one. Optical transparency gradually decreased upon the successive increment in thickness of the as-deposited and annealed films. The surface roughness of as-deposited films increased linearly with the increase in film thickness, but this behaviour was altered in post-annealed films. Spherical grains with high packing density were observed on the as-deposited films, but the grain size was altered substantially on the post-annealed films. The annealed films presented a higher work function than their corresponding as-deposited films. This work presents important insights into the design of photovoltaic devices with an effective deposition process, including a high material utilisation.
关键词： thickness,work function,NiOx,electron beam vapour deposition,annealing,opto-electronic
更新于2025-09-23 15:19:57
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Molecular designing of naphthalene diimide based fullerene-free small organic solar cell - Acceptors with high photovoltaic performance by density functional theory
摘要： With the help of computational chemistry tools, three non-fullerene acceptors, which are 2-methylene-malononitrile (M-1), 2-(3-methyl-5-methylene-2-thioxothiazolidin-4-ylidene) malononitrile (M-2) and 1-methyl-5-methylene-2,6-dioxo-1,2,5,6-tetrahydropyridine-3-carbonitrile (M-3), are designed with naphthalene diimide (NDI) central unit. Their different photovoltaic and optoelectronic properties like absorption spectrum, electrons density, solubility strength, reorganization energies, % ETC from donor to acceptor part, excitation energies, oscillating strength, morphology and crystallinity of device for constructing the thin film bulk hetro junction devices were computed at the WB97XD/6-31 G (d, p) level of density functional theory (DFT). Expected open circuit voltages of designed molecules are high as 4.05 eV to 4.49 eV, which are significantly larger than that of the previously reported 3-methyl-5-methylene-2-thioxothiazolidin-4-one (R) with the value of 3.60 eV at the zero current level. Charge carrier mobilities of designed molecules are high due to having low re-organization energies varying from 0.0163 eV to 0.0280 eV for electron and 0.0160 eV to 0.0190 eV for hole, strong absorption properties between the 420 nm to 550 nm in chloroform and 400 nm to 540 nm in gas phase conditions, respectively.
关键词： opto-electronic properties,non-fullerene acceptors,theoretical calculations,dipole moment,organic solar cells,naphthalene di-imide
更新于2025-09-19 17:13:59
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Opto-Mechanical Interactions in Multi-Core Optical Fibers and their Applications
摘要： Optical fibers containing multiple cores are being developed towards capacity enhancement in space-division multiplexed optical communication networks. In many cases, the fibers are designed for negligible direct coupling of optical power among the cores. The cores remain, however, embedded in a single, mechanically-unified cladding. Elastic (or acoustic) modes supported by the fiber cladding geometry are in overlap with multiple cores. Acoustic waves may be stimulated by light in any core through electrostriction. Once excited, the acoustic waves may induce photo-elastic perturbations to optical waves in other cores as well. Such opto-mechanical coupling gives rise to inter-core cross-phase modulation effects, even when direct optical crosstalk is very weak. The cross-phase modulation spectrum reaches hundreds of megahertz frequencies. It may consist of discrete and narrow peaks, or may become quasi-continuous, depending on the geometric layout. The magnitude of the effect at the resonance frequencies is comparable with that of intra-core cross-phase modulation due to Kerr nonlinearity. Two potential applications are demonstrated: single-frequency opto-electronic oscillators that do not require radio-frequency electrical filters, and point-sensing of liquids outside the cladding of multi-core fibers, where light cannot reach.
关键词： opto-electronic oscillators,multi-core fibers,stimulated Brillouin scattering,optical fiber sensors,Opto-mechanics,nonlinear fiber-optics
更新于2025-09-16 10:30:52
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Self-mode-locked multimode lasers for stabilised RF oscillators
摘要： Low phase noise RF oscillator in modern communication systems and opto-electronic oscillator techniques have achieved superior phase noise. Development and characterisation of coupled symmetric multimode multi-section semiconductor laser pairs are reported for building a chip level RF oscillator. The symmetric laser structure operation is adjusted to achieve a self-mode locking of five modes at 26.4 GHz inter-modal oscillation frequency with the phase noise performance of ?92 dBc/Hz at 10 kHz offset frequency.
关键词： self-mode locking,multimode lasers,RF oscillator,opto-electronic oscillator,phase noise
更新于2025-09-16 10:30:52
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Thermo-optic Aided Tunability of Sr0.6Ba0.4Nb2O6 Thin Film-based Electro-optic Modulator Using Waveguide Coupled SPR Modes
摘要： Present article demonstrates the effective tuning of thermo-optic (TO) properties with the Electro-Optic (EO) modulation characteristics of SBN60 thin films utilizing Waveguide coupled surface plasmon resonance (WCSPR) technique. Electro-optic (EO) coefficient (r) was in turn tuned from a value of 594 pm/V to 621 pm/V with increasing ambient temperature from 296 to 373 K. Tunable percent modulation index varying from 24 to 55% was obtained with increasing ambient temperature at a fixed applied electric field. The obtained results clearly illustrate an efficient thermally tunable EO modulator based on SBN thin film utilizing a simplistic approach with ?n/?T = 88.3 × 10?4K?1.
关键词： Modulation,Opto-electronic,Electro-optic,Thermo-optic,Waveguide
更新于2025-09-12 10:27:22
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Self-Assembled Monolayers with Distributed Dipole Moments Originating from Bipyrimidine Units
摘要： The concept of distributed dipoles in monomolecular self-assembly on solid substrates was tested for the example of thiolate self-assembled monolayers (SAMs) on Au(111) containing dipolar 2,5?-bipyrimidine units. These were attached to a thiol anchoring group either directly or via a phenylene-methylene spacer, with the spacer decoupling the dipolar moiety from the substrate and promoting layer formation. As expected, the SAMs containing spacer groups exhibited a higher quality, including a higher packing density and nearly upright molecular orientation. The electrostatic effects of the dipolar bipyrimidine moieties were tested through C 1s and N 1s photoemission spectra, where electrostatic core-level shifts impact the shapes of the spectra. Additionally, changing the orientation of the dipoles allows a variation of the work function over a range of ~1.35 eV. The experiments were complemented by density-functional theory calculations. The work function tuning range was reasonably high, but smaller than expected considering that for SAMs with a single embedded pyrimidine group per molecule work-function changes already amounted to ~1.0 eV. This behavior is rooted in an asymmetry of the studied SAMs: For dipoles pointing away from the substrate, the expected doubling of the work function change between monopyrimidine and bipyrimidine SAMs essentially occurs. Conversely, for the downward-oriented pyrimidine dipoles, the second polar ring has hardly any effect. Consistent observations were made for the core-level shifts. We discuss several factors, which are potentially responsible for this asymmetry, like disorder, depolarization, or Fermi-level pinning. Of these, the most likely explanation is the adsorption of airborne contaminants interacting with the nitrogen atoms in the immediate vicinity of the outer surface, which are present only in films with downward oriented dipoles. In spite of these complications, some of the introduced distributed dipole SAMs serve as important model systems for understanding electrostatic effects at interfaces. They are also of interest for controlling carrier-injection barriers in organic (opto)electronic devices.
关键词： Bipyrimidine Units,Distributed Dipole Moments,Self-Assembled Monolayers,Organic (Opto)electronic Devices,Work Function Tuning
更新于2025-09-12 10:27:22