Researches of Parameters of Chiral Few-Mode Optical Fiber Pilot Sample with Improved Height of Step Refractive Index Profile

Abstract

This work presents results of researhes of fabricated pilot sample of chiral few-mode optical fiber (FMF) with induced twisting of 10 and 66 revolutions per meter, core diameter 11 µm (that almost corresponds to standard singlemode optical fibers), typical “telecommuniction” cladding diameter 125 µm and improved height of step refractive index profile. Proposed few-mode optical fiber supports 4 guided modes over “C”-band. We considered design and selection of desired technological parameters, based on results of computations, performed by both rigorous and approximation methods. Spectral curves of dispersion parameters are reprented as well as results of experimental measurements near-field laser beam profile and spectral and pulse responces of laser-excited optical signals.

Experimental researches and testing of silica twisted six-GeO2-doped core microstructured optical fiber. Part I: fusion splicing with telecommunication optical fibers and differential mode delay map measurements

“…To implement fabrication of twisted optical fibers, we utilized the technique, presented in work 81 , which is based on preform rotation during the optical fiber drawing. For this purpose, first of all, the motor was installed to the feed unit of tower (in the first stage of modification it was stepper, while further in the final configuration it was replaced by commutator motor), that added the rotation option to the drawing system [82][83][84] with rotation speed up to 2000 revolutions per minute. Because MOF / PCF structure contains air holes (that provide features, much differing from properties of typical telecommunication optical fibers), special matching system was developed, fabricated and installed on the drawing tower to feed excess pressure feeding to the MOF cane for control and management of capillary size under cane rotation during MOF drawing process 85,86 .…”

Silica microstructured optical fiber with centralized inclusion of seven GeO2-doped capillaries and induced twisting. Part I: fabrication of pilot samples

“…Earlier on [29][30][31][32][33] we discussed technological issues of drawing tower modifications to provide fabrication of optical fibers with induced twisting. Here we utilized the same technique, proposed in work 34 , which is based on preform rotation during the drawing.…”

“…As a result, it provided successfully fabrication a set of pilot lengths of silica few-mode optical fibers with improved height of GeO2-doped quasi-step refractive index profile, weakly induced twisting 10 and 66 revolutions per meter (rpm). These manufactured few-mode optical fibers 29,30 have typical "telecommunication" structure: GeO2-doped core with diameter 11 µm, bounded by one outer solid silica cladding with "telecommunication" diameter 125 µm. MOF / PCF structure is strongly more complicated, in comparison with conventional telecommunication optical fibers.…”

Twisted Silica Few-Mode Hollow GeO2-Doped Ring-Core Microstructured Optical Fiber

“…In previously published papers [84][85][86][87][88][89][90], we described in detail all previous successfully performed stages of drawing the tower modifications that provide improvements to the twisting of the fabricated MOF from the initial weak 10 revolutions per meter (rpm) up to 66 rpm [84,85], and then further 100, 400, and 500 rpm [89,90]. We chose to develop the method proposed in [1]: the rotation of the optical fiber preformed during the drawing process.…”

“…We recheck this effect by the same tests, performed for two other MOF samples, which are cut from the opposite ends of the drawn MOFs, but these measured spectra are analogous to those in Figure 7. During the second step, by using a drawing tower, we drew the MOF cane (Figure 6b) with a length of 0.5 m and an outer diameter of 3 mm from the prepared stack under vacuum at 0.5 atm, with a feeding speed of 10 mm per minute, a drawing speed of 0.5 m per minute, and at a drawing temperature of 1920 • C [82,83,87,88].…”