Agilent/Keysight 81623B Optical Power Head

The Keysight 81623B Optical Power Head is a germanium-based detector for precision optical power measurements across the near-infrared spectrum. This remote sensor head integrates with Keysight's 816xA/B Lightwave Mainframes via 81618A or 81619A interface modules, enabling flexible positioning for component characterization, laser analysis, and amplifier testing in telecommunications and research applications. The 5 mm germanium detector delivers calibrated accuracy across distinct wavelength bands, with polarization-insensitive performance and real-time data acquisition capabilities including automated ranging and extended logging.

Technical Specifications

• Sensor Element: Germanium (Ge)


• Detector Diameter: 5 mm


• Wavelength Range: 750 nm to 1800 nm


• Power Range: +10 dBm to -80 dBm


• Detector for Fiber NA: Up to 0.3


• Detector for Open Beams: Up to 5 mm diameter


• Calibration Uncertainty (800–1000 nm): ±2.5%


• Calibration Uncertainty (1000–1650 nm): ±1.7%


• Relative Uncertainty (Polarization): Typically <±0.01 dB (typical <±0.005 dB)


• Relative Uncertainty (Spectral Ripple): Typically <±0.006 dB (typical <±0.003 dB)


• Averaging Time: 100 µs to 10 s


• Data Logging Capacity: Up to 20,000 samples


• Analog Output: 0–2 V via BNC connector


• Dimensions: 55 mm (H) × 80 mm (W) × 250 mm (D)


• Weight: 0.9 kg (without heat sink)

Key Features

• Automatic power ranging with min/max monitoring


• Magnetic D-shaped connector adapters for quick optical input switching


• Accepts 81000xI connectors, bare fiber adapters, and threaded adapters with removable ring


• Analog output proportional to optical signal (requires autoranging disabled for stable DC level)


• Operating temperature range per mainframe specifications; maximum 80% relative humidity (non-condensing); rated to 2000 m altitude

Typical Applications

• Optical component characterization and wavelength-dependent power analysis


• Laser and optical amplifier measurement in telecommunications


• Research-grade spectral power profiling from 750 nm to 1800 nm

Compatibility & Integration

• Compatible Mainframes: Keysight 8163A/B, 8164A/B, 8166A/B Lightwave Mainframes


• Interface Modules: 81618A (single-channel) or 81619A (dual-channel)


• Connector Support: MT ribbon fiber connectors and bare fiber clamps available