Agilent/Keysight 81624A Optical Power Head

The Agilent/Keysight 81624A is an InGaAs optical power head engineered for precise optical power measurements across the near-infrared spectrum. It delivers measurement accuracy as low as ±2.2% at reference conditions (1000 nm to 1630 nm) with exceptional linearity of ±0.02 dB in the CW range from +10 dBm to -70 dBm. The large area 5 mm diameter InGaAs detector provides low polarization dependent loss, low spectral ripple, and high return loss - critical performance metrics for optical component testing and characterization in demanding measurement environments.

Technical Specifications

• Sensor Type: Large area InGaAs detector


• Detector Diameter: 5 mm


• Wavelength Range: 800 nm to 1700 nm


• Power Range: +10 dBm to -90 dBm


• Measurement Accuracy: ±2.2% (1000 nm to 1630 nm at reference conditions)


• Linearity: ±0.02 dB (CW, +10 dBm to -70 dBm)


• Fiber Compatibility: Standard single-mode and multimode (max. 100 µm core, NA < 0.3)

Key Features

• Low polarization dependent loss minimizes measurement errors in polarization-sensitive applications


• Low spectral ripple ensures flat response across the operating wavelength range


• High return loss reduces reflective errors from the detector interface


• Wide dynamic range from +10 dBm to -90 dBm supports both high-power and ultralow-power measurements


• 5 mm active area accommodates both single-mode and multimode fiber coupling

Typical Applications

• Optical component characterization and validation


• In-service optical power monitoring


• Wavelength-dependent power profiling (800 nm to 1700 nm)


• Low-loss optical system testing

Compatibility & Integration The 81624A connects to the Agilent 81618A (single-channel) or 81619A (dual-channel) interface modules, which integrate into Agilent optical mainframes: 8163A/B, 8164A/B, and 8166A/B. This modular architecture enables flexible multi-head measurement configurations within a single chassis.