Investigation of nonlinear optical effects with fibre Bragg gratings and signal-to-noise ratio in the evolution of highly sensitive system

To help the physicians, intra-cavity absorption spectroscopy is being used to design a highly sensitive biomedical sensor for air coming from the lungs. Using the principles of lasing, two different wavelengths (modes) are used to set up this operation. An analysis of our previous results indicates that an in-depth investigation of the fibre Bragg gratings is mandatory which has been done in this work. As the sensor’s operation relies heavily on these FBGs, we resort to calculate and investigate their Bragg wavelengths in accordance with the respective intrinsic properties and data-sheets. Each FBG has been characterized rigorously under numerous temperature conditions for long periods of time and leads to the design limitations of the Bragg wavelength. Afterwards, an intensive measurement and evaluation of signal-to-noise ratio of both modes with respect to the input parameters of the setup is performed. This excessive investigation leads to an increased value of signal-to-noise ratio of 54.5 dB in comparison to previous work and profound implementation attributes that have been discussed in detail.