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We demonstrate the utilization of iron oxide (Fe2O3) as light-absorbing material in an erbium-doped fiber laser (EDFL) for the generation of Q-switched pulses. A sandwich-type saturable absorber (SA) with Fe2O3 nanoparticles between fiber ferrules is proposed. A fiber ferrule tip is tapped onto a cap of index-matching gel, which is then dipped into Fe2O3 nanoparticle powder to allow its deposition through the adhesion effect. By incorporating Fe2O3–SA in an EDFL, self-started and stable Q-switched pulses are attained at a threshold power of 50.1 mW. The pulse repetition rate is tunable from 9.92 kHz to 22.47 kHz, whereas the pulse duration reduces from 38.4 µs to 13.8 µs with the pump power increment. The maximum pulse energy achieved is 36.9 nJ. This work offers a simple integration method of Fe2O3 nanoparticles as potential SAs for the generation of Q-switched pulses.

This study presents the utilization of mill scale waste, which has attracted much attention due to its high content of magnetite (Fe3O4). This work focuses on the extraction of Fe3O4 from mill scale waste via magnetic separation, and ball milling was used to fabricate a microwave absorber. The extracted magnetic powder was ground-milled using two different techniques: (i) a conventional milling technique (CM) and (ii) mechanical alloying (MM) process. The Fe3O4/CM samples were prepared by a conventional milling process using steel pot ball milling, while the Fe3O4/MM samples were prepared using a high-energy ball milling (HEBM) method. The effect of milling time on the structural, phase composition, and electromagnetic properties were examined using X-ray diffraction (XRD) and a vector network analyzer (VNA). XRD confirmed the formation of magnetite after both the magnetic separation and milling processes. The results revealed that Fe3O4 exhibited excellent microwave absorption properties because of the synergistic characteristics of its dielectric and magnetic loss. The results showed that the Fe3O4/CM particle powder had a greater absorption power (reflection loss: <−10 dB) with 99.9% absorption, a minimum reflection loss of −30.83 dB, and an effective bandwidth of 2.30 GHz for 2 mm thick samples. The results revealed the Fe3O4/MM powders had higher absorption properties, including a higher RL of −20.59 dB and a broader bandwidth of 2.43 GHz at a matching thickness of only 1 mm. The higher microwave absorption performance was attributed to the better impedance matching property caused by the porous microstructure. Furthermore, the magnetite, Fe3O4 showed superior microwave absorption characteristics because of the lower value of permittivity, which resulted in better impedance matching. This study presents a low-cost approach method by reutilizing mill scale waste to fabricate a high purity crystalline Fe3O4 with the best potential for designing magnetic nano-sized based microwave absorbers.

Lanthanum and silver co-doped zinc borotellurite glasses having chemical composition of [{[(TeO2)0.7(B2O3)0.3]0.7(ZnO)0.3}0.96 (La NPs)0.04]1-x(Ag2O)x with 0.02 ≤ x ≤ 0.10 molar fraction were fabricated via melt-quenching technique. X-ray diffraction (XRD) analysis confirmed the amorphous nature of the samples through the presence of broad hump instead of sharp peaks. Optical properties of the samples were determined through ultraviolet-visible spectroscopy (UV-Vis) in the range of 220 to 800 nm. Fundamental absorption edge observed in the optical absorption spectra shifts to longer wavelength as the concentration of silver in the glass system increases. Decreasing trend for indirect energy band gap and increasing trend of Urbach energy values with the increment of Ag content suggest the contribution of Ag to the formation of nonbridging oxygen. Enhanced optical properties of the prepared glass hints the possible application of the glass material as optical fiber in photonic field.

Silica borotellurite glasses doped with manganese oxide with chemical formula {[(TeO2)0.7(B2O3)0.3­]0.8[SiO2]0.2}1-x{MnO2}x (where x = 0.0, 0.01, 0.02, 0.03, 0.04 and 0.05 molar fraction) were fabricated. Silica were extracted from the burning process of rice husk. Glass samples were prepared by using the melt-quenching technique. The FTIR spectra showed that the addition of MnO₂ contributed to the transformation of TeO4 to TeO3. The diffraction pattern of XRD showed a broad hump which indicates the amorphous nature of the samples. The result for both optical band gap and Urbach energy showed decreasing trend as the concentration of manganese increased.

The glass samples of zinc borotellurite glass doped with dysprosium nanoparticles with chemical formula TeO20.7B2O30.30.7ZnO0.31-xDy2O3x (where x= 0.01, 0.02, 0.03, 0.04 and 0.05 molar fraction) have been fabricated by using melt quenching technique. In this study, the structural and optical properties of the zinc borotellurite glass doped with dysprosium nanoparticles were characterized by using X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and UV-Vis spectroscopy. From the XRD, the amorphous nature of the glass samples has been confirmed. The infrared spectra revealed four obvious bands which are assigned for BO3, BO4 and TeO4 vibrational groups. The direct and indirect optical band gap, as well as Urbach energy, was calculated through absorption spectra obtained from UV-Vis spectroscopy. From the spectra, it is observed that both direct and indirect optical band gap decreases as the concentration of dysprosium nanoparticles increase. Other than that, the Urbach energy is observed to have an inverse trend with the optical band gap. The Urbach energy is increases as the concentration of dysprosium nanoparticles increases.

A fiber based bend sensor using a uniquely designed Bend-Sensitive Erbium Doped Fiber (BSEDF) is proposed and demonstrated. The BSEDF has two core regions, namely an undoped outer region with a diameter of about 9.38 μm encompassing a doped, inner core region with a diameter of 4.00 μm. The doped core region has about 400 ppm of an Er2O3 dopant. Pumping the BSEDF with a conventional 980 nm laser diode gives an Amplified Spontaneous Emission (ASE) spectrum spanning from 1,510 nm to over 1,560 nm at the output power level of about −58 dBm. The ASE spectrum has a peak power of −52 dBm at a central wavelength of 1,533 nm when not spooled. Spooling the BSEDF with diameters of 10 cm to 2 cm yields decreasing peak powers from −57.0 dBm to −61.8 dBm, while the central wavelength remains unchanged. The output is highly stable over time, with a low temperature sensitivity of around ~0.005 dBm/°C, thus allowing for the development of a highly stable sensor system based in the change of the peak power alone.

With the rapid growth of telecommunications, electromagnetic pollution and interference (EMI) have become critical challenges. This study developed barium hexaferrite-based nanocomposites doped with Ti, Co, Mn, and Ni to enhance EMI shielding capabilities. The nanocomposites (BaFe12O19 and the modified BaTiCoMn0.25Ni0.25Fe10O19) were synthesized using mechanical milling and thermal processing. Advanced analytical techniques such as x-ray diffraction, scanning and transmission electron microscopy, and vector network analysis confirmed the successful incorporation of dopants and revealed remarkable improvements. The BaTiCoMn0.25Ni0.25Fe10O19 variant exhibited enhanced magnetic properties with a coercivity of 308.9 Oe and magnetization of 65.9 emu/g, surpassing BaFe12O19. The optical band gap was increased to 2.3 eV, suitable for high-energy applications. The nanocomposite demonstrated superior EMI shielding, achieving a reflection loss of − 25.0 dB at 10.5 GHz and shielding effectiveness up to − 45.0 dB in the X-band (8.0–12.0 GHz), making it highly efficient for advanced EMI shielding in electronics and telecommunications.

With the rapid growth of telecommunications, electromagnetic pollution and interference (EMI) have become critical challenges. This study developed barium hexaferrite-based nanocomposites doped with Ti, Co, Mn, and Ni to enhance EMI shielding capabilities. The nanocomposites (BaFe 12 O 19 and the modified BaTiCoMn 0.25 Ni 0.25 Fe 10 O 19 ) were synthesized using mechanical milling and thermal processing. Advanced analytical techniques such as x-ray diffraction, scanning and transmission electron microscopy, and vector network analysis confirmed the successful incorporation of dopants and revealed remarkable improvements. The BaTiCoMn 0.25 Ni 0.25 Fe 10 O 19 variant exhibited enhanced magnetic properties with a coercivity of 308.9 Oe and magnetization of 65.9 emu/g, surpassing BaFe 12 O 19 . The optical band gap was increased to 2.3 eV, suitable for high-energy applications. The nanocomposite demonstrated superior EMI shielding, achieving a reflection loss of − 25.0 dB at 10.5 GHz and shielding effectiveness up to − 45.0 dB in the X-band (8.0–12.0 GHz), making it highly efficient for advanced EMI shielding in electronics and telecommunications.

Soda lime silica (SLS) waste as the source of silica (SiO2) and ark clamshell (ACS) as the foaming agent has been utilized to fabricate the low-cost and lightweight foam glass-ceramics. A series of 1 and 6 wt% foam glass-ceramics were successfully prepared by the conventional solid-state sintering method at various sintering temperatures for 60 min. The bulk density of the samples has achieved minimum density (1.014 g/cm3) with maximum expansion (62.31%) at 6 wt% of the ACS content sintered at 800 °C for 60 min. The bulk density increases while the linear shrinkage and total porosity decrease with the progression of ACS contents and sintering temperature, where the results correspond with the FESEM micrograph. The result of XRD and FTIR transmittance spectra have shown that the formation of wollastonite crystal has occurred starting at 6 wt% of the ACS content sintered at 800 °C for 30 min. The highest mechanical performance (3.90 MPa) with an average total porosity (8.04%) is observed for the sample containing 1 wt% of ACS. It can be concluded that the composition of foam glass-ceramics (1 and 6 wt%) and sintering temperatures give significant results to the structural, physical, and mechanical properties of the fabricated foam glass-ceramics.

We demonstrate the utilization of iron oxide (Fe[sub.2]O[sub.3]) as light-absorbing material in an erbium-doped fiber laser (EDFL) for the generation of Q-switched pulses. A sandwich-type saturable absorber (SA) with Fe[sub.2]O[sub.3] nanoparticles between fiber ferrules is proposed. A fiber ferrule tip is tapped onto a cap of index-matching gel, which is then dipped into Fe[sub.2]O[sub.3] nanoparticle powder to allow its deposition through the adhesion effect. By incorporating Fe[sub.2]O[sub.3]–SA in an EDFL, self-started and stable Q-switched pulses are attained at a threshold power of 50.1 mW. The pulse repetition rate is tunable from 9.92 kHz to 22.47 kHz, whereas the pulse duration reduces from 38.4 µs to 13.8 µs with the pump power increment. The maximum pulse energy achieved is 36.9 nJ. This work offers a simple integration method of Fe[sub.2]O[sub.3] nanoparticles as potential SAs for the generation of Q-switched pulses.