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1The 30th International Conference on Advanced Laser Technologies
LS-O-7
ALT'23
Resonant loss reduction of high-order modes in all solid band gap fibers
G. Alagashev, A. Pryamikov
Prokhorov General Physics Institute of the Russian Academy of Sciences, 38 Vavilova Str. Moscow, Russia
alagashevgrigory@gmail. com
All solid band gap fiber (ASBGF) is a relatively simple waveguide micro - structure that can confine radiation in the solid core. The cladding of such fiber consist of the rods with larger refractive index than the surrounding glass matrix form a cladding of such a fiber. It was shown that in the case of ASBGF with even a small number of the cladding rods located on a some circle it is possible to obtain resonant low loss regime for the fundamental core mode for certain values of geometric parameters [1]. In this work we have studied ASBGF with the following parameters: number of rods is N = 6, 9, radius of the circle where rods are located is R = 10-25 ^m, radius of a single rod is r = 2 ^m, refractive index of glass matrix is nglass = 1.45, refractive index contrast is An = +0.05, vacuum wavelength is X = 1 ^m. The cross section of the fiber is shown in Figure 1. Leakage loss of the fundamental core mode (HE11) and high-order mode (HE21) was calculated by multipole method (solid curves) and finite element method (markers) in COMSOL (Fig. 2). It is shown that when the number of rods in the cladding is increased the resonant loss reduction is observed for the highorder modes as well. Thus for N = 9 there are geometric parameters at which the HE21 mode has leakage loss lower than those of the fundamental core mode. The properties of such fibers with reduced high-order modes loss can be used for dispersion management and sensing [2,3] The study was funded by Russian Science Foundation under project # 22 - 22 - 00575.
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Fig. 1. Cross-section Fig. 2. Leakage loss
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[3] E. Li, X. L. Wang, and C. Zhang. Fiber-optic temperature sensor based on interference of selective higher-order modes. 2006.
