In Situ DNA Detection Using a Phase-Demodulated High-Order Intermodal Interferometer Based on an Exposed-Core Microstructure Fiber

In this article, we demonstrate a phasedemodulated high-order intermodal interference based on exposed-core microstructure fiber (ECF), and it is applied for low-concentration in situ deafness gene DNA detection. The simulation results show that the phase sensitivity of the high-order interference mode (LP01-LP(21)a) is about 6x higher than that of the low-order (LP01-LP(11)b), which is different from the traditional wavelength-coded demodulation method. Hybridization experiments of complementary and noncomplementary deafness gene DNA fragments were carried out, and the sensing system was obtained to screen for complementary gene fragments. DNA complementary fragments with concentrations as low as 1 nM can be detected with a corresponding phase variation of 7.394.. The limit of detection (LOD) is as low as 0.046 nM. The experiment and theoretical analyses prove that this fiber optic biosensor can obtain high sensitivity and signal-to-noise ratio with phasedemodulation high-order intermodal interference scheme, which provides an alternative for the subsequent studies of high-sensitivity and high-precision sensors.

Automated summary

In this article, a phasedemodulated high-order intermodal interference based on exposed-core microstructure fiber (ECF) is demonstrated for low-concentration in situ deafness gene DNA detection. The high-order interference mode (LP01-LP(21)a) shows a phase sensitivity about 6 times higher than the low-order mode (LP01-LP(11)b), differing from traditional wavelength-coded demodulation methods. Hybridization experiments confirm that the sensing system can detect complementary gene fragments with concentrations as low as 1 nM, with a corresponding phase variation of 7.394. The detection limit (LOD) is as low as 0.046 nM. The experiment and theoretical analyses prove that this fiber optic biosensor provides a high sensitivity and signal-to-noise ratio for high-sensitivity and high-precision sensors.