Atec Agilent-8169A - Manual (Page 2)

2
The Agilent 11896A
Polarization Controller
Measure very low PDL of DWDM
components
The Agilent 11896A motorized
polarization controller adjusts
polarization and not power. It’s
optical fiber loop design provides
all states of polarization with ex-
tremely small optical insertion-
loss variations (±0.002 dB) over
a wide spectral range (980 nm and
1250 to 1640 nm.) This performance
combination maximizes measure-
ment accuracy for power sensitive
applications, such as polarization-
dependent loss and gain, because
the measurement uncertainty
contributed by the polarization
controller is minimized. The 11896A
provides fast measurements of
DWDM components with a rota-
tion rate of 360° in <0.5 seconds.
Figure 2. The Agilent 11896A
produces all states of polarization
and covers the entire Poincare
sphere
1 in a pseudo-random
manner.
Two Types of Polarization Controllers...
Figure 3. Agilent 11896A
Block Diagram
Figure 4. Orthogonal great circles
on the Poincare sphere
1 show how
the Agilent 8169A synthesizes
relative state-of-polarization points
according to a specified path.
Figure 5. Agilent 8169A
Block Diagram
1 The Poincare sphere is a three dimensional graphing system for viewing all possible states of polarization. Poincare sphere
display is provided by Agilent 8509A/B Lightwave Polarization Analyzer.
Optical
Input
Optical
Output
λ
/4 Fiber Loop
Optical
Input
Optical
Output
Linear
Polarizer
λ /2
Plate
λ
/4
Plate
PDL measurement of DWDM components using Mueller
method is one of the main applications. The Mueller method
stimulates the test path with four precicely known states.
Precise measurement of the corresponding output intensities
allows calculation of the upper row of the Mueller matrix,
from which PDL is in turn calculated. This method is fast,
and ideal for swept wavelength testing of PDL.
The Agilent 8169A
Polarization Controller
´
The Agilent 8169A provides
polarization synthesis relative
to a built-in linear polarizer. The
quarter-wave plate and half-wave
plate are individually adjusted
to create all possible states of
polarization. Predeterministic
algorithms within the Agilent
8169A enable the transition path
from one state of polarization
on the Poincare sphere to another
to be specified along orthogonal great circles. These features
are important because device response data can be correlated
to specific states of polarization input to the test device.