N4374B

Agilent N4374B 4.5 GHz Single-Mode Lightwave Component Analyzer for CATV and Radio over Fiber Data Sheet General Information Agilent’s N4374B Lightwave Component Analyzer (LCA) is optimized for the electro-optical S-parameter measurement for Cable TV (CATV) and Radio over Fiber (RoF) or radio frequency over Glass (RFoG) applications. In modern CATV or RoF/RFoG transmission systems analog signals are directly transmitted over optical fiber. This requires very low distortion of the electro-optical devices at the transmitter and the receiver side. Therefore it is necessary to have very flat transfer characteristic in amplitude and delay. The N4374B LCA is the tool of choice to optimize your design for these parameters. For frequency dependent responsivity measurements the N4374B is the successor of the industry standard 8702 LCA series. It supports 75 Ohm test with a minimum loss pad (MLP). With a completely new design of the optical test set together with the newest ENA based network analyzer, the N4374B guarantees excellent electro-optical measurement performance. It’s the excellent accuracy that improves the yield from tests performed with the N4374B, by narrowing margins needed to pass the tested devices. NIST traceability ensures worldwide comparability of test results. The fully integrated “turnkey” solution reduces time to market, compared to the time-consuming development of a selfmade setup. In addition a unique new calibration concept significantly reduces time from powering up the LCA until the first calibrated measurement can be made. This increases productivity in R&D and on the manufacturing floor. By optimizing the electrical and optical design of the N4374B for lowest noise and ripple, the accuracy has been improved by more than a factor of 5 compared to the 8702 series LCA and is now independent of the electrical reflection coefficient of the device under test. The advanced optical design together with temperaturestabilized transmitter and receiver ensures repeatable measurements over days without recalibration. Using the advanced measurement capabilities of the network analyzer, all S-parameter related characteristics of the device under test, like responsivity, ripple, group delay and 3dB-cutoff frequency, can be qualified with the new N4374B Lightwave Component Analyzer from 100kHz to 4.5 GHz. Key benefits High absolute and relative accuracy measurements improve the yield of development and production processes. With the excellent accuracy and reproducibility, measurement results can be compared among test locations world wide. High confidence and fast time-to-market with a NISTtraceable turnkey solution. Significantly increased productivity using the fast and easy measurement setup with a unique new calibration process leads to lower cost of test. 75 Ohm support Specified phase uncertainty More than 5 times faster than predecessor 8702 series speeds up every test procedure Identical LCA software and remote control across the N437xB family simplifies integration Bias-T included in Network Analyzer Relative frequency response uncertainty: ± 0.6 dB @ 4.5GHz (typ) Absolute frequency response uncertainty: ± 1.3 dB @ 4.5GHz (typ) Noise floor: -103 dB W/A for E/O measurements @ 4.5 GHz -90 dB A/W for O/E measurements @ 4.5 GHz Typical phase uncertanty: ±1.5° max Transmitter wavelength: 1550nm ± 20 nm 1310nm ± 20 nm 1290 - 1610 nm with external source input Built-in optical power meter For fast transmitter power verification Powerful remote control: State of the art programming interface based on Microsoft .NET or COM. Warranty: 1 year warranty is standard for N4374B Lightwave Component Analyzer. Extension to 3 or 5 years available. The network analyzer The N4374B is based on the newest E5071C ENA network analyzer series. The network analyzer includes a Bias-T for biasing the electro-optical components. 2 Agilent N4374B Applications In photonic CATV or RoF transmission systems, it is necessary to design and qualify subcomponents like direct modulated lasers and receivers, which are analog by nature, with different parameters. Those parameters are core to the overall system performance. These electro-optical components significantly influence the overall performance of the transmission system via the following parameters: 3dB bandwidth of the electro-optical transmission Relative frequency response, quantifying the electrooptical shape of the conversion. Absolute frequency response, relating to the conversion efficiency of signals from the input to the output, or indicating the gain of a receiver. Electrical reflection at the RF port Group delay of the electro-optical transfer function Only a careful design of these electro-optical components over a wide modulation signal bandwidth guarantees successful operation in the transmission system. Agilent N4374B Features Turnkey solution In today’s highly competitive environment, short time-tomarket with high quality is essential for new products. Instead of developing a home-grown measurement solution which takes a lot of time and is limited in transferability and support, a fully specified and supported solution helps to focus resources on faster development and on optimizing the manufacturing process. In the N4374B all optical and electrical components are carefully selected and matched to each other to minimize noise and ripple in the measurement traces. Together with the temperature stabilized environment of the core components, this improves the repeatability and the accuracy of the overall system. Extended factory calibration data at various optical power levels ensures accurate and reliable measurements that can only be achieved with an integrated solution like the N4374B. Easy calibration An LCA essentially measures the conversion relation between optical and electrical signals. This is why user calibration of such systems can evolve into a time consuming task. With the new calibration process implemented in the N4374B, the tasks that have to be done by the user are reduced to one pure electrical calibration. The calibration with an electrical calibration module is automated and needs only minimal manual interaction. With the minimum loss pad (MLP) which is part of the LCA shipment the impedance match from 50 Ohm LCA system to 75 Ohm test device can be realized in an easy way. The correction for the 75 Ohm impedance is enabled with one button in the LCA software which uses default data to correct the MLP transfer behavior. For higher accuracy an individual calibration of the MLP can be realized with the adaptor removal tool which is part of each ENA-C Electro-optical components The frequency response of amplified or unamplified detector diodes, modulators and directly modulated lasers typically depends on various parameters, like bias voltages, optical input power, operating current and ambient temperature. To determine the optimum operating point of these devices, an LCA helps by making a fast characterization of the electrooptic transfer function while optimizing these operating conditions. In parallel the LCA also measures the electrical return loss. In manufacturing it is important to be able to monitor the processes regularly to keep up the throughput and yield. In this case the LCA is the tool of choice to monitor transmission characteristics and absolute responsivity of the manufactured device. The remote control of the N4374B offers another tool to improve the productivity by making automated measurements and analysis of the measured data. Built-in performance verification Sometimes it is necessary to make a quick verification of the validity of the calibration and the performance of the system. The N4374B’s unique calibration process allows the user to perform a self-test without external reference devices. This gives full confidence that the system performance is within the user’s required uncertainty bands. Electrical components Electrical components such as amplifiers, filters and transmission lines are used in modern transmission systems and require characterization to ensure optimal performance. Typical measurements are bandwidth, insertion loss or gain, impedance match and group delay. The new switched architecture offers direct access to the electrical outputs and inputs of the network-analyzers just by selecting electrical- to electrical measurement mode in the LCA user interface. 3 State-of-the-art remote control Testing the frequency response of electro-optical components under a wide range of parameters, which is often necessary in qualification cycles, is very time consuming. To support the user in minimizing the effort for performing this huge number of tests, all functions of the LCA can be controlled remotely via LAN over the state-of-the-art Microsoft .NET or COM interface. This interface is identical for all LCA of the N437xB/C series. Based on programming examples for VBA with Excel, Agilent VEE and C++, it is very easy for every user to build applications for their requirements. These examples cover applications like integration of complete LCA measurement sequences. Integrated optical power meter In applications where optical power dependence characterization is needed, the average power meter can be used to set the exact average output power of the LCA transmitter by connecting the LCA optical transmitter output, optionally through an optical attenuator, to the LCA optical receiver input. By adjusting the transmitter output power in the LCA user interface or the optical attenuation, the desired transmitter optical power can be set. In cases where an unexpectedly low responsivity is measured from the device under test, it is very helpful to get a fast indication of the CW optical power that is launched into the LCA receiver. The cause might be a bad connection or a bent fiber in the setup. For this reason too, a measurement of the average optical power at the LCA receiver is very helpful for fast debugging of the test setup. Selectable output power of the transmitter Most PIN diodes and receiver optical subassemblies need to be characterized at various average optical power levels. In this case it is necessary to set the average input power of the device under test to the desired value. The variable average optical output power of the LCA transmitter offers this feature. Together with an external optical attenuator, this range can be extended to all desired optical power levels. Group delay and length measurements In some applications it is necessary to determine the electrical or optical length of a device. With the internal length calibration of the electro-optical paths with reference to the electrical and optical inputs or outputs, it is possible to determine the length of the device under test External optical source input For applications where test of opto-electric devices need to be done at a specific optical wavelength, the N4374B-050 offers an external optical input to the internal modulator where an external tunable laser can be applied. As modulators are polarization sensitive devices, this input is a PMF input to a PMF optical switch to maintain the polarization at the internal modulator. 4 Definitions Generally, all specifications are valid at the stated operating and measurement conditions and settings, with uninterrupted line voltage. Explanation of terms Responsivity For electro-optical devices (e.g. modulators ) this describes the ratio of the optical modulated output signal amplitude compared to the RF input amplitude of the device. For opto-electrical devices (e.g. photodiodes) this describes the ratio of at the RF amplitude at the device output to the amplitude of the modulated optical signal input. . 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 uncertainties changes in performance due to environmental changes and aging of components. Relative frequency response uncertainty Describes the maximum deviation of the shape of a measured trace from the (unknown) real trace. This specification has strong influence on the accuracy of the 3-dB cut-off frequency determined for the device under test. 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. Absolute frequency response uncertainty Describes the maximum difference between any amplitude point of the measured trace and the (unknown) real value. This specification is useful to determine the absolute responsivity of the device versus modulation frequency. General characteristics Give additional information for using the instrument. These are general descriptive terms that do not imply a level of performance. Frequency response repeatability Describes the deviation of repeated measurement without changing any parameter or connection relative to the average of this measurements. Minimum measurable frequency response Describes the average measured responsivity when no modulation signal is present at the device under test. This represents the noise floor of the measurement system. Definition of LCA input and output names LCA electrical port A LCA electrical port B LCA optical output LCA optical input 5 Measurement capabilities 3dB cut-off frequency (S21), Responsivity (S21), Electrical reflection (S11 or S22), Group Delay vs. frequency, Insertion Loss (IL), Transmission bandwidth, all electrical S-parameter measurements. Target test devices Transmitter (E/O) Agilent N4374B Specifications Measurement conditions Modulation frequency range from 10 MHz to 4.5 GHz Foreward and reverse RF power +5 dBm Number of points 899 Number of averages: 1 IFBW 300 Hz Network analyzer set to “stepped sweep – sweep moves in discrete steps” After full two-port electrical calibration using an Electronic Calibration Module, Agilent 85092C, at constant temperature (±1° C) Modulator bias optimization set to “every sweep” Measurement frequency grid equals electrical calibration grid DUT signal delay ≤ 0.1/IF-BW Specified temperature range: +20° C to +26° C. After warm-up time of 90 minutes Using high quality electrical and optical connectors and RF cables in perfect condition Using supplied RF cables (8120-8862) Receiver (O/E) PIN diodes Avalanche photodiodes (APD) Receiver optical subassemblies (ROSA) Optical (O/O) Passive optical components Optical fibers and filters Optical transmission systems 6 Transmitter and Receiver Specifications Optical Test set Operation frequency range Connector type optical input optical output optical source input (rear) RF LCA optical input Operating input wavelength range Maximum linear average input power [f1] Maximum safe average input power Optical return loss (typ.) [f1] Average power measurement range [f1] Option -332, -362 100 kHz to 4.5 GHz SMF angled with Agilent versatile connector interface PMF angled, with Agilent versatile connector interface, polarization orientation aligned with connector key N type, female 1250 nm to 1640 nm [f4] Optical input 1: Optical input 2: Optical input 1: Optical input 2: > 27 dBo Optical input 1: Optical input 2: ±0.5 dBo -25 dBm to +4 dBm on optical input 1 -15 dBm to +14 dBm on optical input 2 +4 dBm +14 dBm +7 dBm +17 dBm Average power measurement uncertainty (typ.) [f1] LCA optical output (internal source) Optical modulation index (OMI) at 1 GHz (typ.) Output wavelength Average output power range Average output power uncertainty (typ.) Average output power stability, 15 minutes (typ.) [f2] > 30 % @ +5 dBm RF power option -100, -102 (1310 ± 20) nm option -101, -102 (1550 ± 20) nm -2 dBm to +4 dBm ±0.5 dBo ±0.5 dBo External optical source input (-050) Optical input power range for typical performance Optical input damage level Typical loss at quadrature bias point Operating input wavelength range +8 dBm to +15dBm +20 dBm 9 dB 1290 nm to 1640 nm [f4] LCA RF test port input Maximum safe input level at port A or B +15 dBm RF, 7V DC [f1] Wavelength within range as specified for LCA optical output [f2] After modulator optimization [f3] Required source characteristics: SMSR : >35 dB, line width 20dB, unmodulated, single mode [f4] Excluding water absorption wavelength 7 Specifications for electro-optical measurements at 1310 nm N4374B system with network analyzer E5071C -245 (E/O mode) Specifications are valid under the stated measurement conditions. At optical input 1 (“+ 7 dBm max”). At optical input 2 (“+ 17 dBm max”), specifications are typically the same for 10 dB higher incident average and modulated optical power. For wavelength: (1310 ±20) nm (option -100, 102). System performance Relative frequency response uncertainty DUT response ≥ -18 dB(W/A) [f1] ±0.5 dBe typ. ≥ -38 dB(W/A) Absolute frequency response uncertainty Frequency response repeatability (typ.) DUT response ≥ -18 dB(W/A) [f1] ±1.3 dBe typ DUT response ≥ -38 dB(W/A) [f1] ±0.02 dBe -98 dB(W/A) typ. ±0.02 dBe -103 dB(W/A) ±0.02 dBe -103 dB(W/A) ±2.2 dBe (±1.3 dBe typ.) ±2.2 dBe (±1.3 dBe typ.) ±0.5 dBe typ. ±0.7 dBe (±0.5 dBe typ.) ±0.5 dBe typ ±0.8 dBe (±0.6 dBe typ.) ±0.6 dBe typ. 10 MHz to 50 MHz 50 MHz to 0.7 GHz 0.7 GHz to 4.5 GHz Minimum measurable frequency response (noise floor ) [f2] [f4] Phase uncertainty (typ.) [f3] Group delay uncertainty DUT response ≥ -38 dB(W/A) [f1] - ±1.5° ±1.5° Derived from phase uncertainty, see section “Group delay uncertainty”. Example: ±1.0° → ±8 ps (0.5 GHz aperture) [f1] For DUT optical peak output power ≤ +7 dBm. [f2] IFBW = 100 Hz. [f3] Except phase wrap aliasing (example: a DUT group delay of 5 ns (1 m cable length) requires a frequency step size of ≤ 0.2 GHz to avoid phase wraps). Excluding a constant group delay offset of