Effect of the PMMA Layer Thickness on the Performance of Lab-on-fiber Radiation Dosimeter

Lab-on-fiber (LOF) technology has diverse applications in different types of sensing and actuating nano-systems. Radiation dosimeter based on LOF can be effectively used to monitor radiation dose, where the optical properties are quantified due to the variation of radiation dose. In this work, we investigate the performance of an optical fiber tip having a patterned PMMA layer which is covered by a thin Au overlay. We observe the shifts in resonant frequency of the reflection spectra according to the variation of PMMA layer. In contrast, PMMA thickness is changed by the dose rate and correspondingly shifts the resonant frequency of the reflection spectra. In this analysis, design frequency ranges from 210 THz to 214 THz (wavelength 1402 nm to 1430nm). With the increase of the PMMA layer thickness, the peak-to-peak difference (in dB) of the reflection spectra S11, S21 decreases, and the minima and maxima point shift in the left-hand side (frequency decreasing in manner). This analysis would help designers to tune important design parameters to enhance the performance of the dosimeter.