Abstract
This paper theoretically describes effective suppression of higher order modes (HOMs) in realistic
large-hollow-core photonic band-gap fibers (PBGFs) and utilizes the use of this class of waveguides for low-loss
data-transmission applications and high-power beam delivery systems. The proposed design strategy is based on the
resonant-coupling mechanism of central air-core modes with defected outer core modes. By incorporating six
7-unit-cell air cores in the cladding of the PBGF with sixfold symmetry, it is possible by resonantly coupling the
light corresponding to the HOMs in a central 19-unit-cell core into the outer 7-unit-cell core, thus significantly
increasing the leakage losses of the HOMs in comparison to those of fundamental mode. We consider a realistic PBGF
structure with hexagonal airholes having rounded corners and derive a surface-mode-free condition of a silica-ring
thickness surrounding the hollow core for both 7-unit-cell and 19-unit-cell cores. Verification regarding the
propagation properties of the proposed design is ensured with a PBGF analysis based on a finite element modal
solver. Numerical results show that the leakage losses of the HOMs can be enhanced in a level of at least three
orders of magnitude over 200-nm wavelength range in comparison to those of the fundamental mode, while in addition,
we show that the incorporation of a realistic air core with optimized silica-ring thickness can eliminate surface
modes and achieve strong confinement into the central core and very low <i>η</i>
-factor for the fundamental mode.
© 2007 IEEE
PDF Article
More Like This
Cited By
You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.
Contact your librarian or system administrator
or
Login to access Optica Member Subscription