The quantification of gases in breath has gained significant attention as a modern diagnosis method due to its non-invasive nature, and as a painless and straightforward method for the early detection of physiological disorders. Several notable clinical applications have been established for disease diagnosis by correlating exhaled breath samples and specific diseases. In addition, diverse breath molecules represent a biomarker of specific illnesses and are precisely identified by the standard analytical method. However, because of the bulky equipment size, expensive cost, and complexity in measurement when using analytical methods, many researchers are focusing on developing highly selective, sensitive, stable, robust, and economical sensors for breath analysis. It is essential to optimize approaches such as breath sampling, biomarker sensing, data analysis, etc. However, the detection of ppb-level biomarkers in exhaled breath is too challenging to solve due to the abundance of interfering gases. We present a brief and comprehensive review of a recent diagnostic technique that employs nanomaterial (NM)-based sensors to identify the volatile organic compounds (VOCs) associated to diseases. Because they are easily fabricated, chemically versatile, and can be integrated with existing sensing platforms, NMs are ideal for such sensors. Initially, this review provides crucial details about certain representative biomarkers found in diseased patients’ exhaled breath and the demand for breath sensors. Subsequently, the review highlights diverse sensor technologies such as electrical, optical, and mass-sensitive gas sensors and describes their sensing capability for detecting the biomarkers’ concentrations and their primary endeavor of diagnosing disease. Finally, the pitfalls and challenges of sensor characteristics are discussed. This article lays the basis for developing high-performance gas sensors based on novel NMs.

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A highly dispersive dual core quasi-periodic photonic crystal fiber is proposed for chromatic dispersion compensation. The dispersion for the dual concentric core fiber is optimized to compensate the chromatic dispersion with a high negative dispersion, accomplishing the communication bandwidth from S-band (1460 nm) to L-band (1625 nm). By precise control of structural parameter we have achieved a maximum dispersion of −18,838 ps/nm-km with the phase matching wavelength centred around 1.55 μm. We also numerically investigate the influence of structural parameter and doping effects and its response on peak dispersion parameter.

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An optical input pulse with a duration of nanosecond to femtosecond propagates through a dispersive nonlinear medium, it is subject to an extreme spectral broadening termed as white light supercontinuum (SC). In PCF, dispersion characteristics can be modified by the waveguide geometric parameters and thereby the nonlinear dynamics can be altered. In this article, the fiber parameters like core diameter, doping percentage, and pitch are varied and analyzed to achieve a conclusive zero-dispersion wavelength (ZDW) and a high nonlinearity. The numerical study presents different designs of solid-core photonic quasi-crystal fiber (PQF) and selection of highly nonlinear fiber with an effective area of 1.14 µm 2 and nonlinearity of 196 W-1-km-1 at 780 nm exhibiting two-zero dispersion wavelength for supercontinuum generation in different regimes. The results exhibit a significant pulse broadening effect when the pump pulse (FWHM) was varied from 25 fs to 100 fs. Similarly, the influences of the pulse energy and peak average power on the bandwidth of the generated SC are studied