This study examines the influence of quenching dynamics on the efficiency of erbium-doped fiber amplifiers (EDFAs) with high erbium-ion (E3+-ions) doping concentrations, comparing pulsed and continuous wave core-pumping methods. Our findings indicate that quenching, driven by energy transfer upconversion, substantially impacts signal gain in these fibers. The core-pumping configuration demonstrated significantly higher gain per unit length than both low-doping EDFAs and cladding-pumping systems, with effective energy storage achievable through short pump pulses to reduce concentration quenching effects. The highly doped homemade fiber (fiber under test - FUT No. 3) achieved a gain per unit length exceeding 8.4 dB/m, outperforming the lower doped commercial fiber (FUT No. 4) by a factor of 6.4, although FUT No. 4 displayed better compatibility with the core-pumping system. Additionally, the highest gain per unit length for a counter-directional, cladding-pumped amplifier configuration with a high-concentration fiber was recorded at 5.9 dB/m at a 1560 nm signal wavelength with a 2 μs pulse duration, positioning FUT No. 3 as a highly efficient option for high-gain applications despite its high doping concentration. Our experimental analysis of quenching dynamics not only highlights an approach for scaling pulse energy using shorter fiber lengths to mitigate nonlinear effects but also provides valuable insights into quenching-influenced gain behavior in pulsed fiber amplifier systems.

We report a record-high 5.5-mJ amplified pulse energy at 980 nm, achieving 0.55 kW peak power using a 1-meter long ultra-large-mode-area ( $290~\mu $ m core) ytterbium fiber in a co-directional, amplifier configuration. Pumped at 915 nm and seeded by a modulated 980-nm laser diode. We provide a detailed fiber spectroscopy analysis, optimizing key parameters—such as seed and pump repetition rates to mitigate thermal load and other detrimental effects (e.g., re-absorption), enabling high-energy output. The amplifier’s performance highlights its applications for high-brightness ultraviolet and visible light generation, and as an efficient pump for erbium-doped fiber systems, advancing their performances in fluorescence imaging, marine engineering and biophotonics. To the best of our knowledge, the achieved output energy of 5.5 mJ is the highest reported to date in an ytterbium-doped-fiber amplifier at 980-nm, while offering simpler fabrication, configuration and enhanced compatibility compared to other fiber systems at similar wavelengths.

Marine protein hydrolysates are valuable sources of antioxidant bioactive peptides but are susceptible to degradation during processing and storage. Encapsulation can improve their stability and facilitate their incorporation into food matrices. This study evaluated the encapsulation and antioxidant activity retention of a sardine protein hydrolysate (SPH) from Opisthonema bulleri, O. libertate, and O. medirastre. The SPH contained 61.88 ± 0.84 g kg⁻¹ crude protein, with 71.58 ± 1.54% of peptides ranging from 1.35 to 17 kDa. SPH was encapsulated by spray drying using maltodextrin and gum arabic under three processing conditions. FTIR revealed spectral changes after encapsulation, while AFM showed differences in nanoscale surface features. Processing conditions significantly affected production yield, surface feature size, and antioxidant activity retention. ESPH1 (150 °C inlet temperature, 60 °C outlet temperature, and 9.4 mL min⁻¹ feed flow rate) showed the highest production yield (69.13 ± 0.72%), smallest surface features (141 ± 32 nm), and antioxidant activity retention of 67.41% for ABTS, 70.76% for DPPH, and 99.85% for FRAP. These findings support spray-dried SPH as a potential powdered antioxidant functional ingredient for incorporation into food formulations.

Modern aquaculture is essential for meeting the increasing global demand for fish and seafood, but its rapid expansion has exposed limitations that threaten long-term sustainability. Major challenges include high disease outbreaks, low nutritional efficiency, and the instability and poor solubility of nutraceuticals and plant-derived compounds. These challenges often create a self-reinforcing feedback loop, amplifying the detrimental effects of one another. Conventional approaches, including antibiotics, chemical treatments, aquafeeds, and chemotherapeutic agents, have shown limited effectiveness, partly due to inefficient delivery systems that can contribute to environmental contamination and antimicrobial resistance. This review discusses nanotechnology-enabled strategies to improve these traditional methods, focusing on nanocarriers and nanoencapsulation techniques, and also mentioning other synthetized nanoparticles and microencapsulation strategies. These systems have succeeded in reducing oxidative degradation and improving bioavailability by enhancing the stability and activity of encapsulated bioactives. The review also evaluates their functional performance, limitations, environmental effects, interactions with different organisms, and regulatory constraints in the industry. Overall, while safe and scalable use of biodegradable nanoscale delivery systems in modern aquaculture has shown great potential, it still depends on careful design, harmonized regulations, and economically feasible manufacturing.