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High-power laser delivery with near-diffraction-limited beam quality is typically limited to tens of metres distances by nonlinearity-induced spectral broadening inside the glass core of delivery fibres. Anti-resonant hollow-core fibres offer not only orders-of-magnitude lower nonlinearity but also loss and modal purity comparable to conventional beam-delivery fibres. Using a single-mode hollow-core nested anti-resonant nodeless fibre with 0.74 dB km−1 loss, we demonstrate the delivery of 1 kW of near-diffraction-limited continuous-wave laser light over a 1 km distance, with a total throughput efficiency of ~80%. From simulations, a further improvement in transmitted power or length of more than one order of magnitude should be possible in such air-filled fibres, and considerably more if the core is evacuated. This paves the way to multi-kilometre, kilowatt-scale power delivery that is potentially useful not only for future manufacturing and subsurface drilling but also for new scientific possibilities in sensing, particle acceleration and gravitational wave detection.Microstructured optical fibre is shown to be able transmit high-power laser light over long distances with high throughput efficiency.

We report the development of an OTDR operating at the emerging wavelength band of 2 μm. A 30dB dynamic range and spatial resolution of 10m is achieved.

We experimentally demonstrate a FM-EDFA supporting 5 spatial modes with reconfigurable differential gain control and excellent gain-flatness obtained through mode-selective bi-directional pumping of a custom fiber with a radially-profiled erbium dopant distribution.

We present the first in-band diode-pumped TDFAs operating in the 2 μm wavelength region and test their application as high performance amplifiers in potential future telecommunication networks. We demonstrate amplification over a 240 nm wide window in the range 1810 - 2050 nm with up to 36 dB gain and noise figure as low as 4.5 dB.

We numerically demonstrate that the few moded erbium doped fiber amplifier models based on linearly polarized and vector modes are equivalent when the fiber core exhibits slight ellipticity and the signals in the guided modes are incoherent. These conditions are fulfilled in a practical mode division multiplexed system.

We show transmission of 20 wavelength-division-multiplexed (WDM) x 3 mode-division-multiplexed (MDM) x 320-Gb/s DP-32QAM modulated channels (spectral efficiency (SE) of 15 bits/s/Hz) over 60km of few-mode fiber (FMF) with inline multi-mode EDFA (MM-EDFA).

We report a direct diode pumped all-fiber tunable laser source at 2 [micro]m with over 250 nm of tuning range. A 3 dB power flatness of 200 nm with a maximum output power of 30 mW at 1930 nm was achieved. The laser has high OSNR of over 50 dB across the whole tuning range.

In 2018, a novel circulatory foot-and-mouth disease virus serotype Asia1 BD-18 (G-IX) lineage containing a unique mutation has emerged in Bangladesh. This emergence may be following the evolutionary roadmap of previously reported lineage. Inappropriate vaccination and inefficient outbreak surveillance possibly contributed to the current episode of emergence.

In this investigation, synthesized Co substituted Ni-Zn ferrites {Ni 0.6 Zn 0.4−x Co x Fe 2 O 4 (for x  = 0.00, 0.05, 0.10, 0.15, 0.20)} followed by double sintering method have been characterized by crystallographic, morphological, electrical and magnetic properties. X-ray diffraction (XRD) analysis as well as Fourier transform infrared (FT-IR) measurements of all the compositions verify the emergence of spinel cubic (single-phase) crystal structure. For Ni–Zn–Co ferrites, a cation dissemination has been suggested from the site occupancy preferences of different cations and its accuracy was confirmed by comparing the theoretically and experimentally computed lattice parameters as well as by measuring the magnetic moment. Scanning electron microscopy (SEM) showed diminished crystallite grains of average size 644 and 677 nm for 15% and 20% Co-doped compositions. An exceptional rise in dielectric constant for 10% Co-doped composite was observed at lower frequencies. AC conductivity of Co-doped ferrites showed that σ AC decreases with increased Co content. A single incomplete semicircle for all the investigated compositions is observed in the Nyquist plot. The impedance and modulus spectrums analysis confirmed that Co substituted samples attain non-Debye kind dielectric relaxation. The maximum relaxation time τ of 4.19 µs was found for 20% Co-doped content. The 15% Co-doped composite exhibits a significant increment in saturation magnetization (87.39 emu/g) and in magnetic moment (3.69 μ B ) . The value of initial permeability decreases noticeably with increased Co addition. Magnetic loss ( tan δ M ) vs. frequency plot shows the beginning of relaxation peaks for all the NZCFO composites at higher (> 10 7 Hz) frequencies.

PurposeHashish consumption is one of the most widespread public health concerns due to its extensive use and high prevalence. This study aims to investigate the association between illness perception and quality of life among hashish users, while also assessing the mediating role of coping strategies.Design/methodology/approachMale hashish users’ with a mean age of 37.9 years (SD = 12.3) were screened from public and private addiction and rehabilitation centers in Districts Peshawar, Kohat and Karak. Data were collected through the Brief Illness Perception Questionnaire, the World Health Organization Quality of Life scale and the Brief Cope scale to assess illness perception, quality of life and coping strategies. Stepwise regression and mediation analysis were performed.FindingsThe findings suggest that illness perception has a significant reverse association with quality of life (r = −0.16, p < 0.01). However, coping strategies have a significantly positive association with quality of life (r = 0.51, p < 0.01) while subcategories, that is, problem-focused, emotion-focused and active avoidance coping were not significantly associated with quality of life.Practical implicationsLower quality of life increases vulnerability to illness perception, and effective coping strategies improve quality of life. This study emphasizes the importance of addressing illness perception and enhancing coping strategies in interventions aimed at improving the quality of life for hashish users.Originality/valueThis novel view provide valuable insights for developing targeted interventions that enhance the well-being of hashish users by addressing both their psychological and behavioral aspects.