Design and analysis for a bend-resistant and large-mode-area photonic crystal fiber with hybrid cladding

Abstract

In this paper, an asymmetric large-mode-area photonic crystal fiber (LMA-PCF) with low bending loss at a smaller bending radius is designed. The finite-element method with a perfectly matched layer boundary is used to analyze the performance of the PCF. To achieve LMA-PCF with low bending loss, the air holes with double lattice constants and different sizes at the core are designed. Numerical results show that this structure can achieve low bending loss and LMA with a smaller bending radius at the wavelength of 1.55 μm. The effective mode area of the fundamental mode is larger than 1000 μm when the bending radius is ≥10 cm. The bending loss of the fundamental mode is just 0.0113 dB/m, and the difference between the fundamental and high-order modes of the bending loss is larger than 10 when the bending radius is 10 cm. Simulation results show this novel PCF can achieve LMA and have effective single-mode operation when the bending orientation angle ranges in ±110°. This novel photonic crystal has potential application in high-power fiber lasers.

High‐Power Laser Systems

“…[ 443 ] Hybrid cladding PCF. [ 444 ] Side‐leakage PCF. [ 446 ] Circular gradient‐diameter PCF (CG‐PCF).…”

“…[77,439,440] Unfortunately, very large mode area PCFs (VLMA-PCFs) with MFD > 50 μm are almost rod fibers, experiencing deadly bending loss that slows down the development of compact fiber laser systems. Therefore, many new flexible designs include double air-hole diameter, [441] double lattice constant, [442] triangular core, [443] hybrid cladding, [444] circular gradient diameter, [445] etc., have been proposed in the past decade. Simulation results prove that these fibers can maintain a bending loss of less than 10 -2 dB m -1 in the fundamental mode [368,441,442,445,446] and EFA exceeding 2000 μm 2 [446] at a bending radius close to 10 cm.…”

Design and Analysis of Ultra-Wideband Highly-Birefringent Bragg Layered Photonic Bandgap Fiber With Concave-Index Cladding

“…FEM could allow design flexibility and is currently an acknowledged numerical method to study HC-PBGFs. The PML boundary condition is employed, which has been proved to accurate and reliable in literatures [20][21][22][23]. From Maxwell's equations the following vectoral wave equation is derived as:…”

“…where n x eff and n y eff are the effective refractive indices of the X-polarized and Y-polarized fundamental modes. The confinement loss L is defined as [23]:…”

“…To the best of our knowledge this is the first time to introduce this Bragg type multilayer concept to the PBG holey fiber, which brings along notable optical benefits. The proposed BL-PBGF is simulated and analyzed by using the Finite Element Method (FEM) [20][21][22][23]. The confinement loss achieves as low as 1 dB/km for single mode operation around 1550 nm and remains below 2 dB/km in the ultrawide 180 nm wavelength range from 1450 nm to 1630 nm, basically 3 times wider than the conventional uniform index PBGF.…”