“…-Ring (or annular)-core optical fibers (pure silica core and cladding with the inclusion of a high refractive index material layer on the core/cladding boundary) [1][2][3][7][8][9][10][11][12][13]; -Ring-core MOFs and PCFs (silica center, bounded by a ring from material/glass (doped silica) with a higher refractive index, and air holes in the periphery) [14,15]; -Hollow-core MOFs and PCFs, also known as hollow-core photonic bandgap fibers (pure silica circular fiber with large air central hole (e.g., "core") and small air holes in the periphery part, placed according to desired designed geometry) [1,2,[16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31]; -Anti-resonant hollow-core fiber (AR-HCF) with complicated geometry: so-called "revolver" fibers-single/double/triple-ring AR-HCF and single/double noodles nested AR-HCF [3,29,[32][33][34] and nodeless nested AR-HCF [3,29,32,33,35,36], "grapefruit" [37,38], "ice-cream"…”