Agilent 8156A Option 201 High-Performance High-Return-Loss Optical Attenuator

Agilent 8156A Option 201 High-Performance High-Return-Loss Optical Attenuator

The Agilent 8156A Option 201 Optical Attenuator is a high-performance, high-return-loss bench instrument designed for controlled attenuation of single-mode optical signals. It provides a 60 dB attenuation range across wavelengths from 1200 nm to 1650 nm, making it suitable for professional fiber optic, telecom, photonics, laboratory, production, and automated test applications.

Option 201 identifies the high-performance, high-return-loss version of the Agilent 8156A. This configuration uses 9/125 µm single-mode fiber and angled-contact optical connections. It provides return loss greater than 60 dB, attenuation accuracy below ±0.1 dB, repeatability below ±0.01 dB, and a minimum attenuation step of 0.001 dB.

The Agilent 8156A is a complete non-modular optical attenuator mainframe. Unlike plug-in attenuator modules that require a separate lightwave platform, the 8156A operates as a dedicated bench instrument. Its front-panel controls, programmable operating modes, optical shutter, internal memory, and GPIB interface support both manual measurements and automated optical test systems.

Features and Benefits of the Agilent 8156A Option 201

The Agilent 8156A Option 201 provides precise optical level control for engineers, technicians, laboratories, production facilities, and service organizations working with single-mode optical communication systems.

• High-performance Option 201 configuration: Provides enhanced attenuation accuracy, repeatability, polarization performance, and return-loss capability.
• 60 dB attenuation range: Supports controlled optical loss from the minimum insertion-loss level through an additional 60 dB of attenuation.
• 1200 nm to 1650 nm wavelength range: Covers common single-mode telecom and photonics test wavelengths, including the 1310 nm and 1550 nm regions.
• 9/125 µm single-mode fiber: Designed for professional single-mode fiber optic measurement systems.
• High return loss: Provides return loss greater than 60 dB with the specified angled-contact configuration.
• Fine attenuation adjustment: Supports a minimum attenuation step of 0.001 dB for precise optical power control.
• High attenuation accuracy: Provides attenuation linearity below ±0.1 dB and typical performance below ±0.05 dB.
• Excellent repeatability: Provides repeatability below ±0.01 dB, with typical performance below ±0.005 dB.
• Low polarization-dependent loss: Provides PDL below 0.075 dB peak-to-peak, with typical performance below 0.02 dB peak-to-peak.
• Low polarization mode dispersion: Provides 4 fs PMD for demanding optical measurement applications.
• Fast settling: Settling time ranges from 20 ms to 400 ms, depending on the attenuation setting.
• High optical input capability: Supports a maximum input level of 23 dBm or 200 mW.
• Programmable operation: Supports GPIB control, SCPI commands, and Agilent 8157A compatibility mode.

Precision Optical Attenuation

The Agilent 8156A Option 201 is designed to introduce a controlled amount of loss into a single-mode optical path. The instrument provides an attenuation range of 60 dB, excluding insertion loss, with a minimum programmable step of 0.001 dB.

This fine adjustment capability is useful when setting optical power at the input of a receiver, simulating fiber-link loss, testing optical power-meter linearity, evaluating component response, or measuring system performance at progressively reduced signal levels.

The attenuation accuracy is specified at less than ±0.1 dB under constant-temperature conditions, with typical performance below ±0.05 dB. Repeatability is specified at less than ±0.01 dB, with typical performance below ±0.005 dB. These characteristics support repeatable optical test sequences in laboratory and automated production environments.

High-Return-Loss Option 201 Configuration

Option 201 is the high-performance, high-return-loss configuration of the Agilent 8156A. It uses angled-contact optical connections and provides return loss greater than 60 dB. The return-loss value is typical and depends in part on the performance and condition of the external optical connectors.

High return loss can be important when testing reflection-sensitive optical components, laser sources, amplifiers, receivers, and communication systems. Reducing reflected optical power helps limit measurement instability and unwanted interaction between the attenuator and other devices in the optical path.

The instrument provides a useful back-reflection range from 5 dB to 60 dB when configured with the required Agilent 81000BR back reflector. The back-reflection operating mode allows the desired return-loss value to be entered, displayed, and adjusted within the limits established by the instrument insertion loss and connector return loss.

Operating Modes and Front-Panel Functions

The Agilent 8156A provides several operating modes for attenuation control, wavelength correction, calibration offsets, sweeping, back-reflection adjustment, optical path control, and storage of frequently used configurations.

• Attenuation mode: Displays the selected attenuation value and allows the operator to vary the optical attenuation.
• Wavelength correction: Allows entry of the operating wavelength for automatic correction of attenuation using stored typical correction values.
• Calibration offset: Provides an offset factor for adjusting the displayed value within a 99.99 dB range.
• Display-to-calibration function: Sets the displayed attenuation value to 0.00 dB for reference-based workflows.
• Sweep mode: Supports manual or automatic upward and downward attenuation sweeps with configurable start, stop, step size, and dwell time.
• Back-reflection mode: Allows a desired return-loss value to be entered and adjusted when the required back-reflector accessory is used.
• Enable and disable function: Uses an internal shutter to interrupt the optical path with greater than 80 dB blocking attenuation.
• Store and recall: Stores and recalls nine user-selectable parameter configurations and provides access to the default setting.

Automatic Wavelength Correction

The Agilent 8156A allows the user to enter the operating wavelength so that the instrument can apply automatic attenuation correction using stored typical correction values. This function supports measurements across the instrument’s 1200 nm to 1650 nm wavelength range.

Wavelength correction is useful when the same attenuator is used with sources operating at different wavelengths. The correct wavelength should be entered before precision measurements so the displayed attenuation reflects the appropriate correction for the selected optical test condition.

Attenuation Sweep Applications

The sweep function supports manual or automatic changes in attenuation. The operator can define the start value, stop value, step size, and dwell time for automatic sweep operation.

Automated attenuation sweeps are useful for receiver sensitivity testing, dynamic-range evaluation, bit error rate measurements, optical threshold testing, power-meter linearity checks, and other procedures requiring optical power to be changed through a controlled sequence.

The 20 ms to 400 ms settling time depends on the actual attenuation setting. Automated test software should allow sufficient settling time before recording measurements at each attenuation level.

Typical Applications

The Agilent 8156A Option 201 Optical Attenuator is suitable for professional applications such as:

• Single-mode optical power control
• Receiver sensitivity testing
• Optical receiver dynamic-range measurement
• Fiber link-loss simulation
• Bit error rate testing
• Optical power-meter linearity testing
• Laser source and transmitter evaluation
• Optical amplifier characterization
• Reflection-sensitive optical measurements
• Passive and active optical component testing
• Laboratory and production test systems
• Automated optical measurement applications

Product Overview

Brand	Agilent Technologies
Model	8156A
Installed Option	201
Option Description	High-performance, high-return-loss version
Product Category	Programmable Single-Mode Optical Attenuator
Instrument Format	Non-modular bench instrument
Fiber Type	9/125 µm single-mode fiber
Connector Contact Type	Angled contact
Primary Application	Precise attenuation and high-return-loss control in single-mode optical test systems
Suitable For	Telecom laboratories, photonics research, component characterization, production testing, receiver evaluation, and automated optical test systems

 

Option 201 Optical Specifications

Specification	Agilent 8156A Option 201 Details
Wavelength Range	1200 nm to 1650 nm
Attenuation Range	60 dB, excluding insertion loss
Minimum Attenuation Step	0.001 dB
Fiber Type	9/125 µm single-mode fiber
Connector Type	Angled contact
Return Loss	Greater than 60 dB
Insertion Loss	Less than 1.8 dB
Attenuation Accuracy	Less than ±0.1 dB
Typical Attenuation Accuracy	Less than ±0.05 dB
Repeatability	Less than ±0.01 dB
Typical Repeatability	Less than ±0.005 dB
Polarization-Dependent Loss	Less than 0.075 dB peak-to-peak
Typical Polarization-Dependent Loss	Less than 0.02 dB peak-to-peak
Polarization Mode Dispersion	4 fs
Useful Back-Reflection Range	5 dB to 60 dB

 

General Performance Characteristics

Characteristic	Details
Settling Time	20 ms to 400 ms, depending on the attenuation setting
Maximum Optical Input Level	23 dBm (200 mW)
Optical Shutter Blocking	Greater than 80 dB
Calibration Offset Range	99.99 dB
Stored User Configurations	Nine
Recommended Recalibration Period	One year
Warm-Up Time	Not required when previously stored within the operating-temperature range

 

GPIB and Automated System Integration

All operating modes and parameters of the Agilent 8156A can be programmed through its GPIB interface. The instrument supports the SCPI command set and includes an Agilent 8157A compatibility mode.

This remote-control capability allows the attenuator to be integrated into automated optical test systems. Test software can set attenuation, enter wavelength values, apply calibration offsets, control attenuation sweeps, operate the shutter, store or recall configurations, and coordinate readings with external optical power meters or receivers.

Remote-Control Feature	Details
Interface	GPIB
Programmable Functions	All supported operating modes and parameters
Command Set	SCPI
Compatibility Mode	Agilent 8157A
GPIB Function Code	SH1, AH1, T6, L4, SR1, RL1, PP0, DC1, DT0, C0

 

Electrical, Environmental, and Mechanical Specifications

Specification	Details
Input Voltage	100 V, 120 V, 220 V, or 240 V RMS ±10%
Line Frequency	48 Hz to 400 Hz
Maximum Power Consumption	90 VA
Operating Temperature	0 °C to 55 °C
Storage Temperature	-40 °C to 70 °C
Humidity	Less than 95% relative humidity from 0 °C to 40 °C
Dimensions	89 mm high x 212.3 mm wide x 345 mm deep
Dimensions, Imperial	3.5 inches high x 8.36 inches wide x 13.6 inches deep
Net Weight	5.3 kg (11.7 lb)
Shipping Weight	9.6 kg (21.2 lb)
Non-Volatile Memory Backup	Maintains current modes and data for at least 10 years after delivery with the instrument switched off

 

Connector Interface Requirements

The Agilent 8156A requires two optical connector interfaces. Option 201 uses an angled-contact optical configuration. The exact connector interfaces installed or included with an individual instrument should be confirmed through the product photographs and listing details.

The specified optical performance was measured at 1310 nm and 1550 nm using a Fabry-Perot laser source, single-mode fiber, and Agilent 81000AI or 81000SI connector interfaces. Return loss depends partly on the performance and cleanliness of the external connectors.

Compatible patch cables, connector polish, key orientation, and interface type should be confirmed before connection. Angled-contact and straight-contact connectors should not be mated directly because their end-face geometries differ.

Measurement Preparation and Optical Interface Care

Before operation, users should verify the wavelength, attenuation setting, connector type, expected optical input level, and required operating mode. The optical input should not exceed the instrument’s maximum input level of 23 dBm or 200 mW.

All optical connector end faces and interfaces should be inspected and cleaned before mating. Contamination can increase insertion loss, reduce return loss, create instability, and affect attenuation repeatability.

Patch cables should be routed with appropriate bend-radius control and strain relief. During precision measurements, cables and connectors should remain stationary to help maintain stable optical coupling and backreflection conditions.

Calibration and Testing Before Shipment

When calibration is technically applicable and supported, the Agilent 8156A Option 201 is calibrated before shipment. The calibration process may include verification of attenuation accuracy, repeatability, insertion loss, return loss, polarization-dependent loss, shutter function, wavelength correction, GPIB control, and other supported operating modes.

Following successful calibration, the instrument may include a calibration label, calibration certificate, and related calibration data, depending on the equipment and calibration service. The recommended recalibration period specified for the Agilent 8156A is one year.

If formal calibration is unavailable or not applicable to the specific instrument, the unit receives comprehensive functional and performance testing. This process may include evaluation of front-panel operation, attenuation control, sweep operation, optical shutter, wavelength entry, offset functions, stored settings, GPIB communication, connector condition, and available optical performance.

This testing helps verify that the equipment operates correctly and that its available functions have been evaluated before it is released for shipment. The exact calibration scope, documentation, test data, and included service records should be confirmed before purchase when these items are required for laboratory, production, regulatory, or quality-management applications.

Buyer Considerations

The Agilent 8156A Option 201 is a configuration-specific high-performance optical attenuator. Buyers should confirm that the 1200 nm to 1650 nm wavelength range, 60 dB attenuation range, 9/125 µm single-mode fiber, angled-contact connector requirement, and greater than 60 dB return loss match the intended application.

The installed connector interfaces should be verified before purchase. Two connector interfaces are required, but connector adapters, patch cables, the Agilent 81000BR back reflector, and the Option 202 back-reflector kit should not be assumed to be included unless specifically identified in the product listing.

Buyers should review the instrument condition, display, controls, optical interfaces, shutter operation, attenuation mechanism, GPIB interface, calibration status, service history, and included accessories.

The Agilent 8156A Option 201 should not be confused with Option 100 or Option 101. Option 201 is specifically the high-performance, high-return-loss configuration with angled-contact optical interfaces and greater than 60 dB return loss.

Why Buy from AssetRelay?

AssetRelay supplies professional equipment and product solutions for fiber optic, telecom, laboratory, production, inspection, cleaning, RF/microwave, electronic test, and photonics applications. The Agilent 8156A Option 201 Optical Attenuator is listed to help engineers, laboratory personnel, production facilities, procurement teams, and service organizations source precise optical attenuation equipment for professional test systems.

Buyers should review the available product photographs, physical condition, installed connector interfaces, included accessories, calibration information, and application requirements before purchase. Confirming these details helps ensure that the instrument matches the intended wavelength range, fiber type, connector polish, optical power level, return-loss requirement, and automated test workflow.

Only accessories specifically identified in the product listing should be considered included. Optical patch cables, connector interfaces, back-reflection accessories, optical power meters, laser sources, cleaning supplies, and GPIB cables may be required separately.