Photonic crystal fiber with a flattened fundamental mode for the fiber lasers

Top-hat beam output of a single-mode microstructured optical fiber: Impact of core index depression

“…(i) First of all, an air-silica cladding (as Ref. [9][10][11] allows refractive index to be very close to silica, which would be very tricky to obtain with a solid homogeneous cladding. Moreover, it also enables to finely adjust the contrast, Δn, between cladding and core indices by adjusting the parameter d/Λ during the final drawing process with fine control of the size of the air holes.…”

“…In the past, several fiber designs (including more recently microstructured optical fibers) [9][10][11][12][13] have been proposed to obtain a flattened fundamental mode but most of these studies were only numerical and fiber designs were usually slightly multimode at the operating wavelength, which is detrimental for many applications. Only few papers report on experimental results [8,14].…”

Design of large mode area multicore photonic crystal fiber with a flat-top mode

“…And the refractive index of the doped area (r b − r a ) in the core of fiber 2 and fiber 3 is set as n = 1.4504 initially. This doping way has already been reported by some researches [3,7]. However, it is the first time for this method introducing into multicore PCFs with square lattice structure.…”

“…The main drawback in the development of high power applications is the nonlinear effect, such as Raman scattering, Brillouin scattering and cross phase modulation (XPM) [2]. Since the nonlinear effects have a strong dependence on optical intensity, a reduction of intensity by increasing effective mode area will reduce the nonlinear effects [3]. The invention of photonic crystal fiber (PCF) provides a novel and effective way to realize large mode area (LMA) by adjusting design parameters appropriately.…”

Design of Photonic Crystal Fiber with Large Mode Area for Flat-top Mode Generation

“…The side length of the resulted square spot is only 2~3 μm [8]. In high-power laser systems, in order to reduce the adverse effects of nonlinear effects [9], it is necessary to increase the effective mode area and reduce the light power density, as larger can effectively reduce the light power density [10]. Therefore, the flat-top beam with a large has high application value.…”