parameters.txt

cudos实例

!       CUDOS Fibre Software sample parameter file
! This parameter file is for finding the fundamental mode of 
! a simple hollow core fibre consisting of large central air hole
! surrounded by two layers of holes  in 
! a dielectric background with refractive index 1.45
! The structure is defined in the parameter file, and
! symmetries are used to reduce the problem.
!
! First define the structure :

pitch=5d0			! center to cetner distance of the air cylinders
cylinder index=(1.d0,0d0)	! air cylinders
cylinder radius=1.75d0		! radius of cylinders
matrix index=(1.45,0d0)		! background refractive index
Nr=3				! Number of rings
MNr=2				! The central cylinder and the first ring of 
				! holes are missing
central cylinder index=(1.0,0.0) ! Define central cylinder index
central cylinder radius=5.55	! and radius
no cladding			! The air cylinders are not surrounded by a jacket or a cladding
no jacket
build fibre			! compiles the above parameter into a structure


! define appropriate range of effective index and the wavelength
! (use a finger diagram to find where an air guided mode can exist)

lambda=2.85  			! sets the wavelength

n_eff_0=(0.97,0d0)			! lower left corner of the region
upper right n_eff corner=(0.99,2d-1)	! upper right corner of the region

! define symmetry classes to be considered
! the fundamental mode belongs to the degenerate classes 3 and 4:
start_mode=3
stop_mode=4

! define Fourier Bessel series struncation order
suggest order=close cylinders		! let the software suggest appropriate
					! Fourier-Bessel
					! series  truncation order
					! with extra care given that the
					! cylinders are relatively close
					! this must be done after defining
					! the n_eff region

! save the structure to hollowcore.txt
! note that we save the structure after having defined the appropriate
! Fourier Bessel series truncation order since this
! parameter is saved with the structure

save fibre=hollowcore.txt

! Now find the modes

search modes				

! end of parameter file
end