Agilent/Keysight 81625A,High Power Optical Head

The Agilent/Keysight 81625A is a high-power optical sensor head designed for precision optical power measurements across extended spectral ranges. Built around an InGaAs detector element with a 5 mm aperture, it delivers accurate measurements from -80 dBm to +20 dBm across the 850 nm to 1650 nm band. The unit integrates with Agilent/Keysight lightwave multimeter mainframes through dedicated interface modules, enabling high-power laser and amplifier characterization in demanding measurement environments.

Technical Specifications

• Sensor Type: InGaAs


• Detector Diameter: 5 mm


• Aperture Diameter: 5 mm


• Wavelength Range: 850 nm to 1650 nm


• Optical Power Input Range: -80 dBm to +20 dBm


• Wavelength Accuracy: ±4.0% (950 nm to 1630 nm); ±2.5%


• Analog Output: Not available


• Physical Dimensions: 55 mm × 80 mm × 250 mm


• Weight: 0.9 kg (without heat sink)

Key Features

• InGaAs sensor element optimized for near-infrared measurements


• Wide dynamic range spanning -80 dBm to +20 dBm


• Broad wavelength coverage from 850 nm to 1650 nm


• Compact 5 mm detector geometry


• Direct integration with Keysight lightwave multimeter ecosystems

Typical Applications

• High-power laser characterization and monitoring


• Optical amplifier output measurement


• Spectral power analysis in telecommunications and fiber-optic systems


• Precision optical power validation across extended wavelength bands

Compatibility & Integration The 81625A requires either the 81618A single optical head interface module or 81619A dual optical head interface module for connection to Agilent/Keysight lightwave multimeter mainframes. This modular architecture enables flexible multi-channel measurement configurations within existing test systems. Product Status: Manufacturer obsolete. Self-support resources available via Keysight website. Repair and calibration services may be available through Keysight Service Centers or authorized third-party providers.