Document
Agilent N7788B/BD Optical Component Analyzer
Data Sheet
Figure 1. N7788BD bench-top mainframe with built-in PC
Figure 2. N7788B bench-top mainframe
Introduction
Agilent Technologies pushes the limits of component measurements with the N7788B component analyzer. Its proprietary technology is comparable with the wellknown Jones-Matrix-Eigenanalysis (JME) which is the standard method for measuring polarization mode dispersion (PMD) or differential group delay (DGD) of optical devices. Compared to the JME, Agilent’s new single scan technology offers a range of advantages: A complete set of parameters: ● DGD/PMD ● PDL ● Power/loss ● TE/TM-loss www.DataSheet4U.com ● Jones matrices ● Mueller matrices ● 2nd-order PMD (depolarization + PCD) ● Principal states of polarization (PSPs)
Key Benefits
● Highest accuracy in a single sweep: no averaging over multiple sweeps required ● High measurement speed: Complete measurement across C/L-band in less than 10 seconds (no need to wait for many averages) ● Robustness against fiber movement/ vibration and drift: Fixing fibers with sticky tape on the table or even operation on isolated optical table is not required! ● No limitation on optical path length of component ● The internal referencing scheme guarantees reliable and accurate measurements.
Applications
● ● ● ● ● Fiber characterization: SMF, PMF, DCF Passive component testing: filters, isolators, circulators Dynamic component / module testing: OADM / ROADM Active component testing: EDFAs, SOAs, VOAs Link test: in-channel measurements across amplifiers
The instrument setup is shown in the Figure 3. A LiNbO3 polarization controller determines the input polarization to the DUT. While the tunable laser source is sweeping over the desired wavelength range, a polarimeter analyzes the output state of polarization while input polarization is being modified. The result will be a highly accurate device characterization with respect to DGD/PDL/loss, etc. Furthermore, the internal optical switch provides continuous self calibration for excellent repeatability. Resolving TE/TM insertion loss The TE/TM-function allows accurate determination of the minimum and maximum loss of the DUT at each wavelength. Due to birefringence, optical filters tend to show different transmission functions depending on the polarization state. As shown in Figure 4, these functions are typically shifted in wavelength depending on the amount of birefringence.
Designed for the manufacturing floor
High throughput A complete analysis across the C and the L band is performed in less than 10 seconds! Software drivers A range of software drivers is available for external control of the system. This allows easy integration in common ERP systems. Remote control Control of the instrument through LAN or via the Internet is supported. This supports automation as well as trouble shooting. Report generation Generating PDF reports is supported. The content including layout is configurable by the user. Real time power readout High throughput measurement of non-connectorized components is supported by providing a real time power readout which enables fiber coupling of the new device Barcode scanner Barcode scanning is supported for quick transfer of the DUT serial number
0 -10
TE/TM loss [dB]
-20 -30 -40 -50 1559 1560 Wavelength [nm] 1561
Figure 4. Polarization-dependent wavelength shift (PD-λ) of a filter.
Agilent N7788B Instrument Setup and Application Examples
DUT Laser in
The capability of performing quick PMD-measurements makes this measurement system well-suited for collecting long-term PMD data. The PC software allows to continuously collect the spectral PMD data and store it on the hard disc. The data can then be visualized as pseudo-color plot (see Figure 5).
PMF
LiNbO3 polarization controller
SMF
Polarimeter
Trigger in
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Power In Trigger out
Microcontroller board
GPIB
USB
Figure 3. Instrument setup
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DGD
DGD
Wavelength
pdf
Time
DGD
Figure 5. Long term DGD measurements.
Wavelength
Particularly for characterizing optical filters, the high dynamic range of the N7788B allows accurate resolution of the filter’s side lobes. The internal reference path allows measurement of insertion loss spectra with excellent accuracy, minimizing the influence of the power characteristics of the tunable laser source.
Due to the excellent spectral resolution, the Agilent N7788B is best suited for intra-channel DGD/PDL characterization. The all-parameter-JME algorithm allows flexible adjustments of the wavelength resolution without the need to repeat the measurement. This allows the user to easily find the optimum trade-off between PDL/DGD accuracy and wavelength resolution.
0 Insertion loss [dB]
0
Insertion loss [dB]
-20
-10
-40
-20
-60 1545
1546 1547 1548 Wavelength [nm]
1549
-30 1521.2
1521.3
1521.4
1521.5
Wavelength [nm]
Figure 7. Loss curve of a DPSK demodulator.
Figure 6. Side lobes of an optical filter.
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Table.