Agilent Keysight 8156A-100 High Power Optical Attenuator

The Agilent/Keysight 8156A-100 is a optical attenuator for precise control of optical power in telecommunications testing and measurement. Operating across 1200 nm to 1650 nm, it delivers 60 dB attenuation range with 0.001 dB resolution and ±0.1 dB accuracy. The instrument accommodates single-mode and 50 µm multimode fiber via external connector interfaces, supporting both R&D and production environments.

A novel single filter design eliminates dark spots and attenuation overshoots or undershoots, ensuring stable performance without ranging artifacts. Repeatability reaches ±0.005 dB typical, while polarization sensitivity remains below 0.075 dBp-p. Insertion loss measures 4.5 dB typical with return loss exceeding 35 dB.

Maximum input power is +23 dBm, with switching time ranging from 20 ms to 400 ms.

Technical Specifications

• Wavelength Range: 1200 nm to 1650 nm


• Attenuation Range: 60 dB


• Resolution: 0.001 dB


• Attenuation Accuracy (Option 100): ±0.1 dB typical


• Attenuation Accuracy (Options 101/201): ±0.05 dB typical


• Polarization Sensitivity (Option 100): <0.075 dBp-p typical


• Polarization Sensitivity (Options 101/201): <0.02 dBp-p typical


• Repeatability: 35 dB (Option 100), >45 dB (Options 101/121), >60 dB (Options 201/221), >22 dB (Option 350)


• Maximum Input Power: +23 dBm


• Switching Time: 20 ms to 400 ms


• Operating Temperature: 0°C to 55°C


• Storage Temperature: -40°C to 80°C


• Humidity: <95% RH (0°C to 40°C)


• Power Requirements: 100/120/220/240 Vrms (±10%), 45–400 Hz, 90 VA max


• Dimensions: 9 mm H × 212.3 mm W × 345 mm D


• Weight: 5.3 kg (net)

Key Features

• Single filter design - no dark spots, overshoots, or undershoots


• Fiber support for single-mode and 50 µm multimode (Option 350)


• HP-IB/GPIB remote control interface


• Programmable back reflector mode with external reference reflector (HP 81000BR) compatibility


• Optional 13 dB monitor tap output on select options (121, 221)


• Multiple configuration options tailoring return loss and insertion loss performance

Typical Applications

• Fiber-optic component characterization and testing


• Telecommunications system validation and debug


• Optical power level regulation in test benches


• Reflection sensitivity measurement and analysis


• Production and manufacturing test environments

Compatibility & Integration The 8156A operates as a mainframe and requires external optical connector interfaces from the Agilent 81000FI series (FC/PC, SC/APC, ST, and other types available). Integration with HP 81000BR reflectors enables back reflector measurements. Multiple performance options - 100, 101, 121, 201, 221, and 350 - allow customization of return loss, insertion loss, monitoring capability, and fiber type support.