two-wave mixing
a nonlinear optical pro-
cess in which two beams of coherent light in-
teract inside nonlinear media or photorefrac-
tive crystals. When two beams of coherent
electromagnetic radiation intersect inside a
nonlinear medium of a photorefractive crys-
tal, the periodic variation of the intensity due
to interference will induce a volume refrac-
tive index grating. The presence of such a
refractive index grating will then affect the
propagation of these two beams. This may
lead to energy coupling. The coupling of the
two beams in nonlinear media is referred to
as two-wave mixing.
two-way channel
two terminal channel in
which both terminals simultaneously trans-
mit and receive using the same channel, thus
disturbing each other’s transmissions.
two-way interleaved
in memory technol-
ogy, a technique that provides faster access
to memory values by interleaving memory
values in two separate modules.
TWTA
traveling-wave tube amplifier. See
traveling wave amplifier
.
type-N connector
named after P. Neill of
Bell labs, this coaxial connector has both a
male and female version. The outer diameter
of the female connector is approximately 5/8
inch with an upper frequency range of about
18 GHz.
typical sequence
for a given probability
mass function
p(x), a particular sequence of
length
n chosen i.i.d. according to p(x) is
typical if its empirical distribution is deemed
close to the true distribution. This notion is
also generalized to include the comparison
of functions of the true and empirical dis-
tributions. For example, entropy–typical se-
quences are used in proving coding theorems
in information theory.
c
2000 by CRC Press LLC