Agilent
N7751A 1-Channel Optical Attenuator and Power Meter
N7752A 2-Channel Optical Attenuator and Power Meter
N7761A 1-Channel Optical Attenuator
N7762A 2-Channel Optical Attenuator
N7764A 4-Channel Optical Attenuator
Data Sheet
Preliminary Version 0.9
Introduction
The Agilent N775xA and N776xA
series compact multi-channel attenu-
ators and power meters are a new
class of remote controlled fiberoptic
instruments for optical transceiver
and network integration test. High
setting speed of attenuation and
power and power measurement
capability, combined with USB,
LAN and GPIB interfaces provides
increased throughput and operational
efficiency to meet today’s challenges
in manufacturing.
Power measurements
In addition, the Agilent N7751A and
N7752A attenuators include two
extra optical power meter channels
for convenient power measurements
and setup calibration.
Key specifications
and features
•
Settling time: 20 ms attenuation,
100 ms power
•
0.1 to 1000 dB/s attenuation
transition speed (selectable)
User calibration processes
Comprehensive offset functionality
allows you to calibrate the optical
path in various test set-ups. There is
an offset for the attenuation factor,
and an independent offset for the
output power level, to calibrate for
losses due to patch cords, connec-
tors and switches. Additionally,
wavelength and offset value pairs
can be stored in a table to com-
pensate for wavelength-dependent
effects in the optical path of the
set-up. This allows you to precisely
set the optical power level directly
at the input interface of your device
under test. With the extra optical
power meter channel, calibration is
even easier and more convenient.
All power related offsets can be
determined by a firmware function
that reads a value from the reference
power meter. The difference
between the power value read by
the reference power meter and the
actual value of the attenuator is
automatically stored as the offset.
Operation Modes
All attenuators feature both attenua-
tion mode and power control mode.
In attenuation mode, the calibrated
value of attenuation in dB can be set.
The rate of attenuation change during
setting can also be adjusted between
0.1 and a very fast 1000 dB/s.
The power control functionality
allows you to set the power level at
the attenuator output. The instrument
uses the feedback signal from a
photodiode after a monitor tap, both
integrated in the instrument, to set
the desired power level at the output
of the module (Figure 1).
When the power control mode is
enabled, the module automatically
corrects for power changes at the
input so that the output power level
you set is maintained. Absolute power
levels can be set with high accuracy
after an initial offset calibration for the
uncertainties at connector interfaces.
•
•
•
•
•
+23 dBm max. input power
≤ 1.2 dB insertion loss
One half-width rack unit
45 dB attenuation range (typ.)
–50 dBm to +20 dBm power setting
range
programs developed using the
Agilent 8157x modular attenuators
•
Fully compatible with setups and
•
Powerful and user-friendly GUI
software
•
Two instrument configurations
can be stored and recalled
Input
Attenuator
Coupler
Output
Power meter
Figure 1. Optical Attenuator with power control
2
The Multi-Channel Attenuator Series –
Product Configurations
N776xA multi-channel optical attenuators with
internal power control
The Agilent N776xA multichannel optical attenuators with 1, 2 and 4 attenuator
channels in one unit provide an excellent combination of versatility and density.
Benefits
•
Compact instrument combines and
integrates multiple functions for
setting attenuation and power levels
and optical power measurement to
reduce CAPEX and floor space.
•
Fast and precise setting of optical
1-channel variable attenuator N7761A
power levels in parallel with
settling times of 100 ms for
improved throughput.
•
The multichannel attenuator sets
and measures several ports at the
same time, saving significant time
characterizing multiport and multi-
channel components and network
equipment.
2-channel variable attenuator N7762A
•
Active power control keeps output
power constant.
•
The instrument can be controlled
4-channel variable attenuator N7764A
via LAN and USB, as well as
GPIB for compatibility with existing
equipment.
•
An easy-to-use and intuitive
graphical user interface speeds up
the integration process.
N775xA multi-channel optical attenuators with
internal power control and external power meter channels
The Agilent N775xA multichannel optical attenuators offer 1 or 2 attenuator
channels combined with two power meter channels in one unit.
1-channel attenuator with two power meter channels N7751A
2-channel attenuator with two power meter channels N7752A
3
The N77xx-Viewer:
An easy-to-use
graphical user interface
The N77xx Windows-based graphical
user interface offers flexible and
convenient control of the instrument
• Easy switching between channels
with tabs
• Overview window with all channels
at a glance
• Two instrument configurations can
be stored and recalled
• Enable or disable the attenuator’s
output with one click
• Choose between setting an
attenuation or an output power
Definitions
Generally, all specifications are valid
at the stated operating and measure-
ment conditions and settings, with
uninterrupted line voltage.
Optical network
integration testing
When integrating and testing network
equipment to test network transmis-
sion performance and network
management, including meshed
networks using ROADMs, attenuators
represent link spans between
network nodes or amplifier stages.
The very fast attenuation and
power setting response of the
Agilent N775xA and N776xA attenu-
ators allows simulation of many
network configurations in a short
time. In the path-blocking mode, fiber
network cuts are emulated. With the
attenuation and power ramp feature,
the attenuation and/or the output
power is changed at a defined rate of
0.1 dB/s to 1000 dB/s. This feature
simulates slow and fast changes
in the fiber network for testing the
network management system.
Specifications (guaranteed)
Describes warranted product
performance that is valid under the
specified conditions. Specifications
include guard bands to account for
the expected statistical performance
distribution, measurement uncertain-
ties changes in performance due to
environmental changes and aging of
components.
Applications
Optical transceiver testing
One of the challenges in testing
transceivers is parallelization of
bit-error-ratio measurements for
multiple-device and multichannel
device measurements. Sensitivity
measurements require fast and
precise setting of optical power levels
in parallel at the receiver inputs
with settling times like 100 ms for
improved throughput.
Typical values (characteristics)
Characteristics describe the product
performance that is usually met but
not guaranteed. Typical values are
based on data from a representative
set of instruments.
General characteristics
Give additional information for using
the instrument. These are general
descriptive terms that do not imply a
level of performance.
4
Technical Specifications
Table 1. Optical attenuator
N7751A, N7752A, N7761A, N7762A, N7764A
Connectivity
Fiber type
Wavelength range
Attenuation range
Attenuation resolution
Range
Resolution
Repeatability
1
Accuracy (uncertainty)
1, 2, 3
0 dB to 40 dB
0.01 dB
± 0.05 dB typ.
typ. ± 0.10 dB for attenuation 0 dB to 10 dB
typ. ± 0.15 dB for attenuation 10 dB to 20 dB
typ. ± 0.50 dB for attenuation 20 dB to 40 dB
Settling time
10
Polarization dependency
5
typ. 20 ms
typ. ≤ 0.15 dB
PP
for attenuation 0 dB to 10 dB
typ. ≤ 0.25 dB
PP
for attenuation 10 dB to 20 dB
typ. ≤ 0.5 dB
PP
for attenuation 20 dB to 40 dB
Insertion loss
2, 6
Attenuation transition speed
Relative uncertainty of monitor power meter
2, 8
Averaging time of monitor power meter
Return loss
Maximum safe input power
Optical path blocking
typ. ≤ 1.2 dB (excluding connectors)
≤ 2.2 dB (including connectors)
7
selectable from 0.1 to 1000 dB/s
±0.05 dB ± 300 pW
2 ms to 1 s
typ. 45 dB
+23 dBm
typ. 45 dB
≤ 0.15 dB
PP9
typ. 100 ms
4
± 0.05 dB
4
± 300 pW
FC/APC angled (Option -022) or
FC/PC straight (Option -021) contact connector interface
9/125 µm SMF 28
1260 nm to 1640 nm
0 dB to 40 dB (45 dB typ.)
0.01 dB
Attenuation setting mode
Power setting mode
–50 dBm to +20 dBm
0.01 dB
± 0.025 dB
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
At constant operating conditions.
For unpolarized light. Temperature constant and between (23 ± 5) °C.
For (1310 ±15) nm, (1490 ±10) nm and (1550 ±15) nm.
For 2 ms averaging time. Output power > –40 dBm, input power < +10 dBm.
For input power > +10 dBm add typ. ± 0.02 dB .
For (1550 ±15) nm. Add typ. 0.05 dB for (1310 ±15) nm and (1490 ±10) nm.
For (1550 ±15) nm. Add typ. 0.20 dB for (1310 ±15) nm and (1490 ±10) nm.
Measured with Agilent reference connectors.
For (1550 ±15) nm.
For 2 ms averaging time. Output power > –30 dBm, input power < +10 dBm.
For 20 dB step.
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