Ultrabend resistant circular photonic crystal fiber design for cancer diagnosis by Raman spectrometer

Abstract

One of the ways to diagnose cancer in its early stages, which can lead to timely treatment, is to use Raman spectroscopy. The Raman spectrum of a material is created by the interaction of light with the material; it determines the exact characteristics and properties of the material, which can be used to distinguish cancerous cells from healthy ones. However, the intensity of this spectrum is weak, and the optical fibers used in these devices must have very little loss and thus have low sensitivity to bending. This paper proposes a circular photonic crystal fiber with a structure in which the losses in different bending radii are significantly reduced. The modified state of the fiber at the wavelength of 1.55 μm supports the transmission of 10 modes propagated in the core. The loss for the fundamental mode at this wavelength and bending radius of 2 mm equals 3.82 × 10 − 16 dB / m, which is considered a low value. As the bending radius decreases further, low-order modes diminish, which are more sensitive to bending than high-order modes. However, their losses are lower than in high-order modes. The critical bending radius for this fiber, with the loss reaching 0.1 dB / m, is equal to 0.096 mm. This low critical bending radius shows the low sensitivity of the proposed fiber to bending. The fiber was examined in different bending radii and wavelengths, and the parameters of this structure were presented for the lowest bending losses, which can be used in Raman spectrometers as spectrum collecting fibers and improve cancer diagnosis devices with Raman spectrum.