Keysight N7784B Datasheet

Keysight Technologies
N7784B High Speed
Polarization Controller

Data Sheet

Introduction

The Keysight Technologies N7784B polarization controller contains a high-speed polarization controller
plus microcontroller-based driving circuitry. This unit can operate in various modes.

As a polarization stabilizer, it provides a stable output state of polarization (SOP) even with uctuations

and drifts of the input SOP as occurring for example through temperature drift and mechanical settling

processes. The stabilized output signal is aligned into a polarization maintaining ber (PMF).

Alternatively, an external electrical feedback signal can be provided for stabilizing the SOP.

As a synchronous scrambler, the device switches the SOP of the output signal in a random (pseudo)

way. Switching of the SOP occurs within a few microseconds. The SOP is stable for a predened time

until it again switches to a new SOP. An electrical trigger input can be used to synchronize the
scrambler with external events.

As an SOP switch, the N7784B allows switching the internal waveplates to user denable angles with

very high speed and repeatability.

As traditional scrambler the N7784B varies the output SOP smoothly in a random/pseudo random way.
The unit does not contain any moving parts and therefore is robust and withstands even rough
environmental conditions. All above-mentioned applications of the N7784B are supported by a PC
software package.

– PC-based application software comes with this instrument.
– Other instrument drivers for various software interfaces are available.

Key Benets

– Comprehensive polarization control and management capabilities.
– Covers S-, C- and L-band plus 1.3 μm window (O-band).
– Compact size.
– Standalone operation.
– Robust, no moving parts.
– PC software package included.

03 Keysight N7784B High Speed Polarization Controller

Applications

– Interferometry: polarization stabilization to maximize

contrast ratio.

– Recirculating loop experiments: loop-synchronous

polarization scrambling.

– System test: polarization sensitivity analysis on link/

transmission quality.

Keysight N7784B instrument setup and
application examples

Optical input

Port I

PC input

SMF

Polarization

controller

Power in

GPIB USB

Figure 2. N7784B instrument setup.

Port II

PC input

DSP based control electronics

SMF

Port III

PBS input

PMF

Pol splitter

Port IV

PBS input

Analog in

Trigger in

Trigger out

Application examples

Interferogram

Sensor

Laser

Figure 3. Interferometry/coherent detection.

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 N7784B allows elimination of such ef fects
by alignment of the signal polarization.

N7784B

high speed

polarization

controller

Amplifier

Trigger

N7784B

high speed

polarization

controller

Fiber loop
Pol contr

Switch

The instrument setup is shown in Figure 2. If a scram­bling or switching operation is desired, only ports I and
II are used. If the SOP of the signal is stabilized and the

signal is fed in a PMF, then port II and port III have to be
connected by an SMF. In this situation, the output signal

is available on port IV. If an external feedback signal is
available for stabilization, only ports I and II are occupied.

Tx unit Rx unit

Computer

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 N7784B is ideally suited to
provide the synchronous scrambling capability in such
experiments.

04 Keysight N7784B High Speed Polarization Controller

Specications 1 N7784B Polarization Controller
Wavelength

Operating wavelength range 1260 nm to 1640 nm
Wavelength range in stabilizer mode

2

1520 nm to 1580 nm

Polarization control and stabilization

SOP switching time (open-loop) < 10 μs
PER at PMF output (typical) > 23 dB
Stabilizer response time (typical)

3

2 ms

Optical power

Insertion loss port I to port II
Insertion loss port III to port IV

4

5

< 3.5 dB (< 3.0 dB, typical)
< 1.8 dB (< 1.4 dB, typical)

PDL port I to port II (typical) C/L-Band < 0.2 dB

O-Band < 0.5 dB

Maximum safe input power Port I 20 dBm

Port III 3 dBm

Input power range in stabilizer mode Port III -30 dBm to 0 dBm

Ordering instructions
Optical connector options

N7784B-021 Straight contact connectors
N7784B-022 Aangled contact connectors

Connector interface

The N7784B should usually be ordered with four 81000xI connector interfaces, depending on desired connector type
(not included).

Accessories

5063-9240 Rack mount kit for 1 unit with filler panel
5063-9212 + 5061-9694 Rack mount parts for 2 units side-by-side

Warranty
Select coverage

Included 3-year warranty (return to Keysight), standard
R-51B-001-5Z 5-year warranty assurance plan (return to Keysight):

Priority warranty service includes one-time coverage for an EOS/ESD failure.

Calibration
Select Keysight calibration plan

R-50C-011-3 3-year calibration assurance plan (return to Keysight):

Priority calibration service covering all calibration costs for 3 years; 15% cheaper
than buying stand-alone calibrations.

R-50C-011-5 5-year calibration assurance plan (return to Keysight):

Priority calibration service covering all calibration costs for 5 years; 20% cheaper
than buying stand-alone calibrations.

1. Ambient temperature change max. ± 0.5 °C since normalization. Specication valid on day of calibration.

2. Outside the stabilizer wavelength range, the PER at PMF output may be degraded.

3. Input power at port III > –30 dBm, response to an immediate step of 180° on the Poincaré sphere.

4. For SOP scrambling/switching, only ports I/II are used.

5. Valid for optimum input polarization at PBS input (Port III). Add insertion loss of por t I/II and obtain total insertion loss for SOP stabilizing mode.

05 Keysight N7784B High Speed Polarization Controller

Specications 1N7784B Polarization Controller (continued)
General characteristics

Dimensions (D x W x H) 380 mm x 213 mm x 88 mm

(excluding front and back rubber cushions and handle)
Weight Approx. 4 kg
Recommended recalibration period 24 months
Operating temperature +5 °C to +40 °C
Operating humidity 0% to 80%, non-condensing
Altitude The maximum operating altitude is 2000 m.
Pollution protection Pollution degree 2.
Warm-up time 20 minutes
Interfaces The instruments can be controlled via USB or GPIB interfaces
Power consumption Line power: AC 100 to 240 V ± 10%, 50/60 Hz, 60 VA max.

Keysight | N7784B High Speed Polarization Controller Data Sheet

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Canada [phone]
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Mexico 001 800 254 2440
United States [phone]

Asia Pacic

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(BP-04-23-14)

This information is subject to change without notice.

© Keysight Technologies, 2013- 2014
Published in USA, August 3, 2014

5989-8113EN

www.keysight.com