L
nl
( = 1/(P
0
)), nonlinear length, where P
0
is the peak power
vacuum wavelength
eff
i
ð¼ 2=
ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
k
2
n
2
i
2
p
Þ, the effective transverse wavelength in subregion i
L inter-hole spacing, period, or pitch
n
2
i
nonlinear refractive index of subregion i
n
z
axial or z-component of refractive index
n
m
phase index of guided mode
n
max
maximum axial index supported by the PCF cladding (fundamental
space-filling mode)
n
q
1
¼
ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
P
i
n
2
i
a
i
=
P
i
a
i
q
, the area-averaged refractive index of an arbi-
trary region q of a microstructured fiber, where n
i
and a
i
are respectively
the refractive index and area of subregion i
! angular frequency of light
¼ k
ffiffiffiffiffiffiffiffiffiffiffiffiffi
n
2
g
1
q
, normalized frequency parameter used in the evalua-
tion of Figure (14.4) ...