Cutoff Wavelength Research Articles

Fabrication, structural, and enhanced mechanical behavior of MgO substituted PMMA composites for dental applications

The most common denture material used for dentistry is poly-methyl-methacrylate (PMMA). Usually, the polymeric PMMA material has numerous biological, mechanical and cost-effective shortcomings. Hence, to resolve such types of drawbacks, attempts have been made to investigate fillers of the PMMA like alumina (Al2O3), silica (SiO2), zirconia (ZrO2) etc. For the enhancement of the PMMA properties a suitable additive is required for its orthopedic applications. Herein, the main motive of this study was to synthesize a magnesium oxide (MgO) reinforced polymer-based hybrid nano-composites by using heat cure method with superior optical, biological and mechanical characteristics. For the structural and vibrational studies of the composites, XRD and FT-IR were carried out. Herein, the percentage of crystallinity for all the fabricated composites were also calculated and found to be 14.79–30.31. Various physical and optical parameters such as density, band gap, Urbach energy, cutoff energy, cutoff wavelength, steepness parameter, electron–phonon interaction, refractive index, and optical dielectric constant were also studied and their values are found to be in the range of 1.21–1.394 g/cm3, 5.44–5.48 eV, 0.167–0.027 eV, 5.68 eV, 218 nm, 0.156–0.962, 4.273–0.693, 1.937–1.932, and 3.752–3.731 respectively. To evaluate the mechanical properties like compressive strength, flexural strength, and fracture toughness of the composites a Universal Testing Machine (UTM) was used and their values were 60.3 and 101 MPa, 78 and 40.3 MPa, 5.85 and 9.8 MPa-m1/2 respectively. Tribological tests of the composites were also carried out. In order to check the toxicity, MTT assay was also carried out for the PM0 and PM15 [(x)MgO + (100 − x) (C5O2H8)n] (x = 0 and 15) composites. This study provides a comprehensive insight into the structural, physical, optical, and biological features of the fabricated PMMA-MgO composites, highlighting the potential of the PM15 composite with its enhanced density, mechanical strength, and excellent biocompatibility for denture applications.

Performance of LWIR to VLWIR barrier photodetectors based on M-structure superlattices.

Antimonide superlattice materials with tunable energy bands, high electron mobility, and easy attainment of good uniformity in large-area materials, are considered to be the material of choice for third-generation infrared photodetectors. Based on energy band engineering, this paper designs a series of long-wave infrared(LWIR) to very-long-wave infrared(VLWIR) photodetectors by employing M-structure superlattice(M-SL) as both absorber layer and barrier layer. The photodetectors' performances at different temperatures are simulated in this manuscript. At 77K, while minimizing the lattice mismatch, effectively suppresses the dark current of the device which can be as low as 1× 10-8A/cm2, with a quantum efficiency reaching 20.85% and normalized detectivity achieves 4.78×1011 cm·Hz1/2/W for LWIR photodetector with a cutoff wavelength of 11.1 μm. For the VLWIR photodetector with a cutoff wavelength of 16.7 μm, the corresponding figures are 1×10-6A/cm2, 16.77% and 3.09×1010 cm·Hz1/2/W, respectively.

Crystal growth, structural, optical, mechanical characterization and quantum chemical analysis by DFT of an organic nonlinear optical single crystal 4-Hydroxy pyridinium succinate for photonic and optoelectronic devices

A new organic nonlinear optical single crystal 4-Hydroxypyridinium Succinate was synthesized and grown successfully by slow evaporation method using methanol as solvent at ambient temperature. Single crystal X –ray diffraction studies on the grown crystal reveals that 4HPS crystallizes into orthorhombic structure with the non-centrosymmetric space group (Pna21). In structural point of view, the 4-Hydroxypyridinium cation is bonded to the hydrogen succinate anion by direct electron conjugation through nitrogen atom. In addition, the UV visible transmittance spectrum implies that the crystal has high transparency domain in the entire UV visible region with a lower cut-off wavelength of 286 nm. The various functional groups present in the crystal and their frequency assignments are derived from FTIR spectral analysis. The Photoluminescence spectrum brings forth that the grown crystal has violet emission property. The microhardness measurements testify that the crystal belongs to soft material category with reasonable hardness parameters. The compound was found to be thermally stable up to 188 °C without any weight loss from the TGA and DTG traces. The detailed quantum chemical calculation done by density functional theory (DFT) indicates the Homo –Lumo energy gap of the molecule is 3. 956 eV and 4. 289 eV for α and β wave functions respectively. The Laser induced damage threshold of the crystal investigated using Nd: YAG laser of 1064 nm radiation was found to be 21. 93 Gw/cm2. The second harmonic generation efficiency of the 4HPS crystal was confirmed by the emission of green light under Kurtz and Perry powder test.

Effect of zirconium oxide nanoparticles on thermal, optical, and radiation shielding properties of Bi2O3-B2O3-MnO2 glasses

This study has explored the DSC, UV–Vis absorption spectroscopy, gamma ray and neutron shielding properties of Bi2O3-B2O3-MnO2: ZrO2 glasses. It demonstrates a unique approach to photon shielding analysis using JENDL/PD-2016 photonuclear data and employs a validated spherical neutron model for neutron shielding. Five transparent glasses were prepared with the chemical composition (in mol%) of 29Bi2O3-70B2O3-(1-x)MnO2: xZrO2, and labeled as MZ0.00 (for x = 0), MZ0.25 (for x = 0.25), MZ0.50 (for x = 0.5), MZ0.75 (for x = 0.75) and MZ1.00 (for x = 1). The glass ceramic nature of the samples has been characterized by DTA thermograms. The glass forming ability parameters (Kgl, S & H) were found to be highest for the sample MZ1.00. The UV–Visible optical absorption spectra have been interpreted, and hence the cut-off wavelength (λcut-off) and optical band gap (Eo) were evaluated. The absorption spectra have revealed the co-existence of manganese ions in three stable valence states Mn4+, Mn3+ and Mn2+ in the samples. When ZrO2 nanoparticles were added in the composition up to x = 0.50 mol%, the red shift in the cut-off wavelength (λcut-off) with gradual shrinkage in optical band gap (Eo) has been observed. Also, the linear and non-linear optical parameters viz., refractive index (no), non-linear refractive index (n2), linear optical susceptibility (χ(1)) and non-linear optical susceptibility (χ(3)) have been evaluated. These parameters showcased that B-O, Bi-O, Mn-O, Zr-O, etc. bonds could be strengthened by subsequent reduction of polarization of the trivalent ions (B3+ ions, Bi3+ ions and Mn3+ ions) in the glass system at higher concentrations of ZrO2. Photoatomic and photonuclear attenuation studies portrayed that the sample MZ0.50 has the lowest photon shielding capability. The fast neutron effective removal cross section (ΣR) was observed to be the highest for the sample MZ1.00. Thus, these glasses can be used to design the thermally stable transparent glasses, tunable optical elements, and radiation shielding materials.

Synthesis, structure, growth, characterization and quantum chemical studies on 2-amino-5-bromopyridinium trichloroacetate: A novel phasematchable organic NLO single crystal

Organic crystals have become excellent candidates towards nonlinear optical (NLO) applications as they possess superior second and third order optical nonlinearities and high electro-optic coefficients when compared with their inorganic counterparts. In this direction, 2-Amino-5-bromopyridinium trichloroacetate (2A5BPT), a new organic second-order nonlinear optical compound is synthesized and optical grade single crystals are formed utilizing a slow evaporation solution growth approach at room temperature while using methanol as the solvent. Single crystal X-ray diffraction study shows that the title compound is assigned to monoclinic crystal system having non-centrosymmetric space group Cc. The crystal is transparent ( ̴ 85%) throughout the whole visible spectrum, according to the Ultraviolet-Visble (UV–Vis) spectra, with a cutoff wavelength of 367 nm and an optical energy band gap Eg of 3.32 eV. The crystal possesses good thermal stability. The compound has a 1.6 times greater powder second harmonic generation (SHG) efficiency than potassium dihydrogen phosphate (KDP). The phase matchability of the 2A5BPT is studied through particle size dependence of SHG. The intermolecular connection demonstrated by numerous inter contacts has been shown by a molecular Hirshfeld surface analysis of the crystal structure, and the related 2-dimensional finger print analysis further evaluates the individual contribution from each atom. In order to examine the first order hyperpolarizability, molecular electrostatic potential, and Highest occupied molecular orbital-Lowest unoccupied molecular orbital (HOMO-LUMO) energies, the quantum chemical calculations for the title molecule (2A5BPT) were carried out by density functional theory (DFT) utilizing the B3LYP/6–311++G(d,p) basis set. According to these results, the 2A5BPT crystal could be suitable for optoelectronic applications.

High performance type-II InAs/GaSb superlattice infrared photodetectors with a short cut-off wavelength

High performance type-II InAs/GaSb superlattice infrared photodetectors with a short cut-off wavelength

Sensor performance and cut-off wavelength tradeoffs of III-V focal plane arrays

Sensor performance and cut-off wavelength tradeoffs of III-V focal plane arrays

Bending Loss and Cut-Off Wavelength Properties of Randomly Coupled Multi-Core Fiber

Bending Loss and Cut-Off Wavelength Properties of Randomly Coupled Multi-Core Fiber

K2MgMoP2O10 and K3Mg2MoP3O14: two new molybdophosphates exhibiting different optical anisotropies induced by variable dimensionality of the anion framework.

By introducing the d0 metal cation Mo6+ into phosphates, two new molybdophosphates, K2MgMoP2O10 and K3Mg2MoP3O14, were synthesized by spontaneous crystallization, and their structures were determined by single-crystal X-ray diffraction. K2MgMoP2O10 shows a two-dimensional layer composed of the uncommon eight-membered ring [Mo2P2O16] formed by [MoO6] and [PO4], while K3Mg2MoP3O14 shows isolated [MoP3O14] clusters composed of [MoO5] and [PO4]. K2MgMoP2O10 and K3Mg2MoP3O14 have UV cut-off wavelengths of 277 and 271 nm, respectively, which are significantly shorter than those of most recently published molybdophosphates. To the best of our acknowledge, K2MgMoP2O10 exhibits the largest birefringence (a calculated value of 0.187 at 546 nm) among reported alkali metal or alkaline earth metal molybdophosphates, which provides a way to explore new birefringent materials. First-principles analysis of the electronic structure shows that the large birefringence of K2MgMoP2O10 mainly originates from the [MoO6] units.

Room-temperature nanostructured PbSe/CdSe mid-infrared photodetector: Annealing effects

Room-temperature (RT) photoconductor using mid-wave infrared (MWIR) nanostructured lead selenide (PbSe)/cadmium selenide (CdSe) is presented on a commercially available silicon dioxide on silicon (100) (SiO2/Si) wafer. This device is fabricated through vapor phase deposition (VPD) and subsequently annealed in oxygen to create interconnected nanostructures, which establish efficient pathways for photogenerated carriers and passivate defects within the material. RT specific detectivity (D*) of 8.57 × 108 Jones and a peak D* of 2.49 × 109 Jones are achieved with interband cut-off wavelength of 4 μm. Additionally, the utilization of nanostructured thin film deposition on cost-effective SiO2/Si(100) substrates via the affordable VPD method significantly reduces production costs and facilitates the potential of monolithic integration with Si-based readout integrated circuitry enabling low-cost large-scale production.

Si-Based Graded GeSn Waveguide Photodetectors with 2.61 μm Cutoff Wavelength for Mid-Infrared Silicon Photonics

Si-Based Graded GeSn Waveguide Photodetectors with 2.61 μm Cutoff Wavelength for Mid-Infrared Silicon Photonics

Growth and characterization of organic 2-methylbenzimidazole 4-Aminobenzoate Single crystal for Opto-electronic device applications

A new organic material of 2-Methylbenzimidazole 4-Aminobenzoate (2MIAB) with a size of 5 × 4 × 3 mm3 was grown by solvent evaporation solution growth method. The SCXRD studies reveal that the 2MIAB crystal has a monoclinic crystal structure and belongs to the space group P21/nn number is 4 unit cell parameters are a=7.8319(3) Å, b=20.6465(8) Å, c=9.0432(3) Å, α =90°, β =90.4140°, γ =90°and V =1462.26(9) Å 3. The hkl planes are identified through Powder XRD analysis. The functional groups present in the 2MIAB crystal were determined from FTIR spectral analysis. The UV–Vis spectral analysis of 2MIAB shows a high transmittance range of 99% and a cut-off wavelength of approximately 315 nm. The surface morphology of the 2MIAB compound is examined through FE-SEM analysis. The thermal studies reveal that the grown crystal is stable up to 134 °C. dielectric constant in free space (ϵ0) and dielectric loss (tanδ) of 2MIAB crystal at varying temperatures (313 K, 323 K, 333 K) are recorded with a frequency range of 50 Hz to 5 MHz. The load-dependent hardness of the 2MIAB crystal was analyzed using Vicker’s microhardness test. The optical limiting was performed by Q-switch Nd: YAG laser with a wavelength of 532 nm and intensity of 2.46×1012 W/m2 (pulse rate of 9 ns and energy of 100 μJ ). We employed First-principles density functional theory and ab-initio molecular dynamics simulations to study the electronic and optical properties of the 2MIAB material. We demonstrate that this material is semiconductor in nature, with an energy band gap of 3.26 eV and significant absorption in the UV light range.

An experimental and computational exploration on noncovalent interactions, spectroscopic and nonlinear optical properties of novel creatininium cyanoacetate single crystal

A novel creatininium cyanoacetate (CCA) single crystal is synthesized by the slow evaporation technique and characterized by various experimental techniques such as FT-IR, FT-Raman and UV–visible spectral methods. Similar techniques are also investigated by the computational methods using Gaussian 09 software. The structural parameters, natural bond orbital (NBO), frontier molecular orbital (FMO), molecular electrostatic potential (MEP) and nonlinear optical (NLO) investigations are performed utilizing the DFT method with B3LYP/6-311G(d,p) basis set. The polarizable continuum model (PCM) has been used to identify the effect of various solvents (DMSO, ethanol, methanol, water) on the energy gap, excitation and NLO properties of CCA molecule. Fukui analysis is performed to identify the sites prone to nucleophilic and electrophilic attacks. Different topological methods including electron localization function (ELF), localized orbital locator (LOL), independent gradient model (IGM) and interaction region indicator (IRI) has been performed to quantify the noncovalent interaction and to analyse the weak interaction region. The UV–visible analysis indicates that the CCA crystal was optically transparent and has lower cut-off wavelength. The hole-electron analysis is performed to identify the characteristics of six excitations. The third-order NLO activity of the CCA compound is performed using the Z-scan technique and is compared with some related NLO materials. The substantial NLO response suggests that the CCA molecule can be significant for its utilization in advanced NLO applications.

High-responsivity on-chip waveguide coupled germanium photodetector for 2 μm waveband

Recently, the emerging 2 μm waveband has gained increasing interest due to its great potential for a wide scope of applications. Compared with the existing optical communication windows at shorter wavelengths, it also offers distinct advantages of lower nonlinear absorption, better fabrication tolerance, and larger free carrier plasma effects for silicon photonics, which has been a proven device technology. While much progress has been witnessed for silicon photonics at the 2 μm waveband, the primary challenge still exists for on-chip detectors. Despite the maturity and compatibility of the waveguide coupled photodetectors made of germanium, the 2 μm regime is far beyond its cutoff wavelength. In this work, we demonstrate an efficient and high-speed on-chip waveguide-coupled germanium photodetector operating at the 2 μm waveband. The weak sub-bandgap absorption of epitaxial germanium is greatly enhanced by a lateral separation absorption charge multiplication structure. The detector is fabricated by the standard process offered by a commercial foundry. The device has a benchmark performance with responsivity of 1.05 A/W and 3 dB bandwidth of 7.12 GHz, which is able to receive high-speed signals with up to 20 Gbit/s data rate. The availability of such an efficient and fast on-chip detector circumvents the barriers between silicon photonic integrated circuits and the potential applications at the 2 μm waveband.

Tunable Ga2O3 solar-blind photosensing performance via thermal reorder engineering and energy-band modulation

As an ultra-wide bandgap semiconductor, gallium oxide (Ga2O3) has been extensively applied in solar-blind photodetectors (PDs) owing to the absorbance cut-off wavelength of shorter than 280 nm, and the optimized technologies of detection performance is seriously essential for its further usages. Herein, a feasible thermal reorder engineering method was performed through annealing Ga2O3 films in vacuum, O2 and oxygen plasma atmospheres, realizing to tune solar-blind photosensing performance of Ga2O3 PDs. Thermal treatment, in fact a crystal reorder process, significantly suppressed the noise in Ga2O3-based PDs and enhanced the photo-sensitivity, with the dark current decreasing from 154.63 pA to 269 fA and photo-to-dark current ratio magically raising from 288 to 2.85 × 104. This achievement is dependent of energy-band modulation in Ga2O3 semiconductor, that is certified by first-principles calculation. Additionally, annealing in oxygen atmospheres notably reduces the concentration of oxygen vacancies in the surface of films, thereby improving the performance of the PDs; the oxygen vacancy is extremely concerned in oxide semiconductors in the view of physics of surface defects. In all, this work could display a promising guidance for modulating the performance of PDs based on wide bandgap oxide semiconductor, especially for hot Ga2O3 issue.

Broadband quantum cascade detectors with a cutoff wavelength of 20 μm

An InP-based photovoltaic quantum cascade detector with a cutoff wavelength of 20 μm is reported. A wave function tailored bound-to-miniband diagonal-transition active structure is proposed for the optical detection, effectively improving the photocurrent extraction efficiency and absorption strength, reducing the dark current leakage and consequently enhancing the responsivity and detectivity. The device demonstrates a broadband response of 16–20 μm over the operating temperature range. At 17.8 μm, a peak responsivity of 29.6 mA/W and a Johnson noise limited detectivity of 9 × 1010 Jones is obtained with a mesa of 200 μm × 200 μm, while maintaining a responsivity of 3.7 mA/W at 20 μm.

K4ZnV5O15Cl: A Congruent‐Melting Mid‐Infrared Nonlinear Optical Crystal Combined with Strong Second‐Harmonic Generation and High Laser‐Induced Damage Threshold

AbstractIt is extremely challenging to accomplish second‐harmonic generation (SHG) in the whole mid‐infrared (MIR) region for oxide crystals due to their short IR absorption cutoff wavelengths. Herein, a new MIR nonlinear optical (NLO) crystal of K4ZnV5O15Cl (KZVC) is designed and synthesized by the aliovalent substitution of [VIIIO5] with [ZnIIO4Cl] based on the K2(VO)(V2O7) matrix. KZVC features an ordered 2D [ZnV5O15Cl]∞ layered structure comprising [ZnO4Cl] / [VO5] square pyramids and [VO4] tetrahedron as functional units. Importantly, KZVC shows excellently balanced performances of strong SHG responses (12 × KDP @ 1064 nm, 1.1 × AgGaS2 @ 2.05 µm), broad IR transparency range (0.52‒10 µm), congruent‐melting behavior, and highest laser‐induced damage threshold (LIDT) (60 × AgGaS2 @ 1064 nm) among the reported vanadates. Most remarkably, KZVC represents the first example in the oxide‐based IR NLO crystals that can achieve phase matching in a wide wavelength range extending from 1.8 to 10 µm, fully covering the important MIR atmospheric windows (3‒5 µm).

B2O3–TeO2–ZnO–Na2O–Nd2O3 glass matrices: A comprehensive study of physical, structural, optical, and thermoluminescence properties

The present study reveals the effect of Nd3+ in sodium zinc borotellurite glasses for photonic and dosimetric applications. The melt quenching technique was employed to prepare glass samples for different Nd2O3 compositions (0.0–1.0 mol%) with the empirical chemical relation (60-x)B2O3+20TeO2+10ZnO+10Na2O+xNd2O3. The glass samples were characterized via different techniques for their physical, structural, optical and thermoluminescence behaviour. The Archimede's principle was used to analyse the physical parameters, including density (ρ), molar volume (Vm), and oxygen packing density (OPD). XRD spectra indicated the amorphous nature of fabricated glasses and Fourier transform infrared spectroscopy (FTIR) revealed ZnO, TeO3, TeO4, BO3, BO4 units and Nd–O bonds present in the glass matrix. The values for indirect (Eopt1) gap, Urbach energy (ΔE), cut-off wavelength (λc) and other optical parameters were determined from the optical absorption spectra. Thermoluminescence (TL) response of the prepared glasses was analyzed for gamma dose of 1 kGy–13 kGy, among which NBT 0.2 glass sample showed strongest TL intensity at 5 kGy with non-monotonic behaviour. With the use of Computerised Glow Curve Deconvolution (CGCD), various trap parameters, including activation energy (E), order of kinetics (b) and frequency factor (s) have been identified. Low effective atomic number of these glasses, along with their optimal TL response makes them effective for radiation monitoring, pasteurization of sea food and decomposition of drugs at high doses.

Enhanced Characterisation Studies and Synthesis of Undoped and Copper Doped-Organic Nonlinear Optical Single Crystal: L-Alanine Aluminium Nitrate

Single crystals of untreated and copper (Cu2+) metal ion-doped L-alanine aluminium nitrate (LAAN), a room-temperature slow evaporation organic nonlinear optical material. Single crystals were studied for structural, spectral, optical, hardness, secondorder non-linear optical, electrical [(alternating current (AC) and direct current (DC)], and photoconductivity properties as they grew. Crystallinity, monoclinic structure with space collection P21, and lattice specifications were deliberate using single crystal X-ray diffraction investigation. The existence of functional clusters is revealed by the spectral properties, and the means of vibration of various molecular clusters existing in LAAN were evaluated using Fourier transform infrared (FTIR). The low cut-off wavelength and transmittance properties were determined using optical analysis. The band gap energy of LAAN and Cu-doped LAAN crystals was estimated to be 3.40 eV and 2.70 eV, respectively, using the Tauc plot. It was revealed that pure crystals had a lower dielectric constant than crystals that had been doped with copper. After doping with rising temperatures, AC conductivity started to rise. With the use of the Kurtz and Perry approach, the effectiveness of the grown crystal’s second harmonic generation was computed, Cu-doped LAAN was discovered to be 3.3 times more prominent than potassium dihydrogen phosphate (KDP) and 2.2 times more prominent than pure LAAN crystals. The nonlinear optical characteristics of LAAN crystals have therefore been improved by copper doping. It is most suited for use in electro-optic applications like laser technology, telecommunications and optical signal processing because of its negative photoconductivity.

Self-powered AlGaN-based MSM solar-blind ultraviolet photodetectors with high Al-content AlxGa1−xN/AlyGa1−yN asymmetrical heterostructure

An Al0.4Ga0.6N-based metal–semiconductor–metal (MSM) ultraviolet (UV) photodetector (PD) based on intentionally asymmetrical polarized Al0.55Ga0.45N/Al0.4Ga0.6N/Al0.65Ga0.35N heterostructure has been fabricated and investigated, which achieves the self-powered capabilities. Operated at zero bias, the device presents an ultralow dark current of 7.8 × 10−13 A, a high peak responsivity of 0.04 A/W at ∼275 nm, a cut-off wavelength at ∼285 nm, and a corresponding detectivity of 3.1 × 1012 Jones. In comparison, the device with symmetrical heterostructure has no response at 0 V, confirming the effect of the proposed asymmetrical MSM structure. Furthermore, it is expressly demonstrated that the structure provides an asymmetrical energy band due to different barrier heights at the metal/Al0.4Ga0.6N and metal/Al0.55Ga0.45N/Al0.4Ga0.6N Schottky contacts and enhances the built-in electric field in the Al0.4Ga0.6N active layer owing to its polarization effect through simulations theoretically. Therefore, the improvement of photogenerated carrier transport can be obtained at 0 V, contributing to the high-performance self-powered UV PD.