HP 8156A Optical Attenunator Option 121

The HP 8156A Optical Attenuator with Option 121 is a programmable instrument for precise optical power control across single-mode fiber systems. Delivering 60 dB attenuation range with 0.001 dB resolution and ±0.05 dB accuracy, it supports R&D, production testing, and calibration in telecommunications and component characterization. Option 121 adds a built-in monitor output (13 dB tap) and 45 dB return loss performance, enabling direct measurement of attenuated signal power without external instrumentation. The no-ranging single filter design eliminates dark spots and attenuation overshoots, ensuring repeatable ±0.005 dB performance across the 1200 nm to 1650 nm wavelength band. Polarization sensitivity remains below 0.02 dB peak-to-peak, critical for precision measurements in polarization-dependent applications.

– Technical Specifications

• Wavelength Range: 1200 nm to 1650 nm
• Attenuation Range: 60 dB
• Resolution: 0.001 dB
• Attenuation Accuracy: ±0.05 dB
• Insertion Loss: 3.3 dB typical (includes two connector losses)
• Return Loss: >45 dB
• Polarization Sensitivity: <0.02 dB peak-to-peak
• Repeatability: ±0.005 dB
• Switching Time: 20–400 ms
• Maximum Input Power: +23 dBm
• Fiber Type: Single-mode (9 µm)
• Interface: HP-IB (GPIB)
• Dimensions: 212.3 mm W × 89 mm H × 345 mm D
• Weight: 5.3 kg net; 9.6 kg shipping

– Key Features

• Programmable attenuation with automatic sweep capability (up and down)
• Wavelength compensation with automatic attenuation correction
• Monitor output for real-time signal power measurement at attenuator output
• Back reflector mode for component and system reflection sensitivity measurement
• Single filter design—no ranging gaps or attenuation discontinuities

– Typical Applications

• Fast telecommunications system R&D and production testing
• Optical component calibration and characterization
• Reflection sensitivity and return loss measurements
• Signal power level control in fiber optic test benches

– Compatibility & Integration

Requires HP 81000xI Series optical interface connectors (sold separately). Option 121 configuration uses straight physical contact (PC) connectors. Back reflector operation requires external HP 81000BR reference reflector.