Agilent/Keysight 81626B,High Power Optical Head

The Keysight/Agilent 81626B is a high-power optical head designed for precision optical signal analysis across the 850 nm to 1650 nm wavelength range. This sensor module integrates with Keysight's 81618A (single-channel) or 81619A (dual-channel) interface modules to enable accurate optical power measurements in critical test environments. The 81626B features a large-area 5 mm InGaAs detector optimized for low polarization-dependent loss (PDL) and minimal spectral ripple, delivering measurement uncertainties as low as ±0.002 dB under standard conditions.

Its broad dynamic range spans +27 dBm to −70 dBm (1250–1650 nm) or +23 dBm to −70 dBm (850–1650 nm), accommodating both high and low optical power levels in a single measurement session. An analog output (BNC connector, 0–2 V proportional to signal strength) enables direct signal representation for systems requiring real-time waveform capture or external processing.

Technical Specifications

• Sensor: InGaAs, Ø 5 mm


• Wavelength range: 850 nm to 1650 nm


• Power range: +27 dBm to −70 dBm (1250–1650 nm); +23 dBm to −70 dBm (850–1650 nm)


• PDL uncertainty: Typically ±0.002 dB


• Spectral ripple uncertainty: Typically ±0.002 dB


• Optional uncertainty (special calibration): ±2.5%


• Return loss: > 60 dB typical (D-shape adapter 81001xx)


• Noise (peak-to-peak): < 100 pW (1200–1630 nm); < 400 pW (800–1200 nm)


• Minimum averaging time: 100 µs


• Analog output: BNC connector, 0–2 V range (autoranging must be disabled)


• Operating temperature: 0°C to 40°C


• Warm-up time: 40 min


• Recalibration interval: 2 years


• Dimensions: 57 mm × 66 mm × 156 mm


• Weight: 0.5 kg

Key Features

• Large-area detector minimizes noise and extends dynamic range


• Magnetic quick-change D-shaped adapter interface


• Removable 81624DD adapter ring supports threaded connector types


• Low PDL and spectral ripple for high-confidence measurements

Typical Applications

• Optical communications component verification


• System integration and acceptance testing


• Research and development


• High-accuracy optical power characterization

Compatibility & Integration Operates with Keysight 8163A/B, 8164A/B, and 8166A/B lightwave mainframes via 81618A or 81619A interface modules. Supports fiber adapters for standard connector types, MT ribbon connectors, and bare fiber clamps.