Abstract
A newer and efficient solid core with air holes and ring based circular photonic crystal fiber (C-PCF) design is proposed, developed, and studied. The C-PCF structure with a ring core and three layers of air holes is developed to communicate terahertz frequency of the range of 1 THz to 3 THz. Finite element method (FEM) is used to optimize the position, shape and dimensions of air holes and refractive index (RI) of material for the proposed PCF design and check the efficiency to support different orbital angular momentum (OAM) modes for communication. Our novel designed C-PCF supports multiple stable modes with mode purity above 0.9. Confinement loss is in the range of 10-12 dB/cm, highest effective mode area in the order of 1 mm2 is achieved in the investigated study for 3 THz transmission. The study observes that the performance of PCF is strongly dependent on RI of core and cladding.
In this paper, we theoretically designed and numerically studied a high-resolution and ultrasensitive photonic crystal fiber temperature sensor by selective filling of a liquid with high thermo-optic coefficient in one of the airholes of the fiber. The finite element method was utilized to study the propagation characteristics and the modal birefringence of the fiber under different ambient temperatures. A large base birefringence value of 7.7 × 10−4 as well as a large birefringence sensitivity of almost 29% to a 10 °C temperature variation was achieved for the optimized fiber design with liquid chloroform between 15 °C and 35 °C. We also studied the performance of the proposed optical fiber in a temperature sensing Sagnac interferometer. An average linear temperature sensitivity of 17.53 nm/°C with an average resolution of 5.7 × 10−4 °C was achieved over a temperature range of 20 °C (15 °C to 35 °C).
With the help of numerical simulation, we study the propagation of light in an all-glass photonic crystal fiber. A comparison of the spectral characteristics of a fiber with the idealized hexagonal structure and a fiber with transverse profile deformations is conducted. The calculations use methods based on a spatial Fourier transform. It is shown that total internal reflection modes and the fundamental mode of the photonic bandgap can be excited simultaneously. Structural deformation of a photonic crystal fiber results in the shifting and narrowing of the photonic bandgap. Excitation of the total internal reflection modes leads to increased absorption on the boundaries of the spectral band of the fiber.
Efficient Photonic Crystal Fiber Design for Higher OAM Modes with Low Loss Towards Next Generation THz Communication