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This paper presents a highly negative dispersion-compensating photonic crystal fiber (DC-PCF) with multiple zero dispersion wavelengths (ZDWs) within the telecommunication bands. The multiple ZDWs of the PCF may lead to high spectral densities than those of other PCFs with few ZDWs. The full-vectorial finite element method with a perfectly matched layer (PML) is used to investigate the optical properties of the PCFs. The numerical analysis shows that the proposed PCF, i.e., PCF (b), exhibits multiple ZDWS and also achieves a high negative chromatic dispersion of −15089.0 ps/nm·km at 1.55 μm wavelength, with the multiple ZDWs occurring within the range from 0.8 to 2.0 μm range. Other optical properties such as the confinement loss of 0.059 dB/km, the birefringence of 4.11×10−1, the nonlinearity of 18.92 W−1km−1, and a normalized frequency of 2.633 was also achieved at 1.55 μm wavelength. These characteristics make the PCF suitable for high-speed, long-distance optical communication systems, optical sensing, soliton pulse transmission, and polarization-maintaining applications.

This paper presents a single-polarization filter based on PCF with plasmonic layers of gold and indium tin oxide (ITO). The plasmonic materials are metallic gold and ITO coated on the inner walls of two extra-large vertically arranged air holes. The resonance effect is triggered by guided modes propagating through the silica core and coupling to the coating areas. The finite element method is used to analyze the properties of the filter for the two fundamental orthogonal polarizations. A filtering effect is achieved in the communication window by optimizing the structural factors as well as gold film and ITO deposition thicknesses. When the filter is 1 mm long, the obtained filtering effect is 1319.689 dB/cm for the y-polarization and 31.881 dB/cm for the x-polarization, thus efficiently attenuating the y-component at a communication window of 1.15 μm. With a filtering bandwidth of 602 nm, the proposed filter shows superior characteristics compared with previously reported results. Applications of the proposed plasmonic PCF-based filter can be found in polarization-maintaining and polarization-suppressing systems for optical sensing and broadband transmission.

Background. There exist continuing challenges with communication medium used during health service provision. These challenges relate to clients and health institution, intra- and interhealth institution communications. This study reviewed the existing healthcare communication medium from the perspectives of clients and health professionals at a tertiary hospital in Ghana. Methods. Cross-sectional design was employed with a multilevel sampling method to select a total of 650 participants consisting of 303 clients, 303 health workers, and 44 hospital directorate managers for the study. A structured survey questionnaire was used to collect data from respondents. Results. Close to ninety percent (89.8%) of staff resort to direct means (face-to-face medium) to communicate among each other. Majority (64.4%) of them also communicated with management through meetings sections. Nearly all healthcare providers (97.4%) communicated with clients through direct means (face-to-face medium). Almost all forms of communication between the hospital management members and the general public were done through letters and official memos. Conclusions. The study revealed blended forms of communication media used by health providers and health service consumers. These differences in medium of communication could amount to possible difficulties such as lack of information and truncation of information flow. Developing a systematic way of information flow using a common information platform will improve access to health services.