N7786B [AGILENT]
Polarization Synthesizer; 极化合成
| 型号： | N7786B |
| 厂家： | 
AGILENT TECHNOLOGIES, LTD. |
| 描述： | Polarization Synthesizer |
| 文件： | 总4页 (文件大小：110K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Agilent N7786B
Polarization
Synthesizer
Data Sheet
SOP switching occurs within a few microseconds. An
electrical trigger input can be used to synchronize the
scrambler with external events.
As an SOP switch, the N7786B cycles through a
sequence of SOPs with a speed of more than 40 KHz,
which corresponds to a cycle time of less than 25
microseconds. The sequence of SOPs can easily be
defined by the user using Stokes coefficients.
Figure 1. N7786B Bench-top Instrument
As a traditional scrambler, the N7786B varies the
output SOP in a random way.
Introduction
Full coverage of the Poincaré Sphere is achieved within
a few ms.
The Agilent N7786B contains a high-speed Lithium-
Niobate based polarization controller and a polarization
analyzer plus a microcontroller-based driving circuitry.
As a polarization analyzer, the instrument provides
truly high-speed capabilities: More than 500K samples
can be taken with a sample rate of up to 1 Megasample
per second.
This unit can operate in various modes:
As a polarization stabilizer, it provides a stable output
state of polarization (SOP) even with fluctuations and
drifts of the input SOP. The stabilized output signal is
guided in a standard single-mode fiber (SMF). The out-
put SOP can be defined in the following ways:
The unit does not contain any moving parts, and
therefore is robust and withstands even rough
environmental conditions.
All above-mentioned applications of the N7786B are
supported by Agilent PC software that comes with this
instrument.
●
Set-and-forget: When the front button is pushed,
the current SOP is stored and maintained, even if
polarization changes occur on the instrument input.
Defined stokes: The target output SOP can be
defined by the user using the Stokes parameters.
As a synchronous scrambler, the device switches
the SOP of the output signal in a random (pseudo)
way with a cycling speed of up to 100 KSOPs/s.
●
●
Various instrument drivers and connectivity to external
applications are provided through a DLL interface.
Examples are included.
Application examples
Key Benefits
N7786B
polarization
synthesizer
Amplifier
Tx
DCF
●
Comprehensive polarization
stabilization/control
Amplifier
DCF
●
●
●
Switching capabilities
Reset-free/endless operation
Covers entire range from 1.3 µm
window up to the L-band
Eye-diagram
Amplifier
BERT
Amplifier
DCF
Rx
DCF
Figure 3. Transmission experiments
●
●
●
Compact size
Standalone operation
Robust, no moving parts
The transmission quality of links is known to depend on
the state of polarization (SOP) of the launching signal. The
N7786B is well suited to launch the modulated signal with
predefined SOPs into the link. This allows probing for a
range of SOPs on the Poincaré sphere to get information
about particular polarization issues of a link.
N7785B
synchronous
scrambler
Applications
●
●
●
●
Transmission system test: polarization sensitivity
analysis on link / transmission quality
Fiber loop
Pol contr
Recirculating loop experiments:
loop-synchronous polarization scrambling
Interferometry: polarization stabilization to
maximize contrast ratio
Polarization analysis
Switch
Rx unit
Tx unit
Computer
Agilent N7786B Instrument Setup and
Application Examples
Figure 4. Recirculating loop
The results obtained in re-circulating loop experiments
depend heavily on the PMD and PDL properties of the loop.
Loop synchronous polarization scrambling schemes have
proven to be necessary for generating results comparable to
deployed systems. The N7786B is ideally suited to provide
the synchronous scrambling capability in such experiments.
Interferogram
Input port
Output port
Polarization
analysis
SMF
SMF
Polarization controller
Trigger in
Sensor
Power In
Microcontroller board
GPIB
Trigger out
N7786B
polarization
synthesizer
Laser
USB
Figure 2. Instrument setup
Figure 5. Interferometry/coherent detection
The instrument setup is shown in Figure 2. A DSP-based
electronics controls the polarization analyzer as well as the
polarization controller. The SOP can be stabilized by means
of a closed-loop operation of the DSP.
Fiber-optic-based interferometers or coherent receiver
schemes need polarization stabilization in order to avoid
fading problems of the interference signal. These fading
effects are caused by orthogonally polarized fractions of
the light. The N7786B allows elimination of such effects
by alignment of the signal polarization.
2
Agilent N7786B Polarization Synthesizer Data Sheet
Table 1: Specifications1 N7786B Polarization Synthesizer
Wavelength
Specification wavelength range
1270 nm ... 1375 nm, 1460 nm ... 1620 nm (Opt 400, O/C/L-Band)
1460 nm ... 1620 nm (Opt 500, C/L-Band)
1260 nm ... 1640 nm
Operating wavelength range2)
Polarization Control and Stabilization
SOP switching time (non deterministic)
SOP cycling time6)
< 10 µs
< 25 µs
Remaining SOP error after deterministic SOP
< 3° at input SOP movement rate of 1.2 rad/s
< 6.5° at input SOP movement rate of 40 rad/s
setting (typical)7)
Polarization Analysis
SOP uncertainty (typical)
1,5°
DOP uncertainty
2,0ꢀ
0,5ꢀ
DOP uncertainty after user3),5) calibration (typical)
Optical Power Measurement
Relative power uncertainty3)
C/L-Band:
O-Band:
140 mdB ( 120 mdB typ.)
160 mdB ( 140 mdB typ.)
Input power range
Optical Power
-38 dBm ... +19 dBm
Insertion loss
PDL (typical)
< 4.0 dB (< 3.5 dB, typ)
< 0.2 dB
Maximum safe input power
20 dBm
1) Ambient temperature change max. 0.5°C since normalization. Specification valid on day of calibration.
2) SOP/DOP measurements are possible outside the specification wavelength range if the user performs a manual
calibration.
3) Input power > -20 dBm.
4) DOP > 95ꢀ.
5) User calibration requires a source with a known DOP.
6) The instrument adaptively finds the polarization controller settings to let the SOP cycle through user-defined polarization
states (closed loop operation). After having found these settings, the SOP can cycle through the polarization states in open
loop operation.
7) This value is defined to be 5 times the standard deviation of the angular SOP error on the Poincaré sphere. Valid if con-
troller is turned on. Power at instrument input > -10 dBm.
Agilent N7786B Polarization Synthesizer Data Sheet
3
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Product specifications and descriptions in this
document subject to change without notice.
© Agilent Technologies, Inc. 2008
Printed in USA, April 30, 2008
5989-8115EN
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