Agilent/Keysight 81634A,InGaAs Optical Head (Large Area)

The Agilent/Keysight 81634A is an InGaAs optical power measurement head engineered for precision characterization across the 800 nm to 1700 nm wavelength range. This module interfaces with Agilent/Keysight 816x series lightwave mainframes to deliver accurate optical power measurements in communications systems and component testing. The large-area InGaAs sensor provides excellent sensitivity across broad spectral bands with measurement accuracy of 2.5% at reference conditions (1000 nm to 1630 nm).

Technical Specifications

• Sensor Element: InGaAs


• Wavelength Range: 800 nm to 1700 nm


• Power Range: +10 dBm to −110 dBm, +10 dBm to −90 dBm, or +10 dBm to −80 dBm (selectable)


• Measurement Accuracy: 2.5% (1000 nm to 1630 nm at 23°C ±5°C)


• Linearity: 55 dB


• Operating Temperature: 0°C to 40°C (specifications valid at 23°C ±5°C)


• Humidity: Non-condensing


• Data Storage: Up to 100,000 samples


• Fiber Compatibility: Standard SM and MM up to 62.5 µm core

Key Features

• Supports both single-channel (81618A) and dual-channel (81619A) interface modules


• SCPI-compliant programming; compatible with 8164A, 8166A, and 8153A systems


• Data logging with min/max value tracking and stability measurements


• Trigger synchronization for spectral measurements with tunable laser sources


• 81634B variant includes BNC analog output signal


• Dimensions: 57 mm × 66 mm × 156 mm; weight: 0.5 kg (81634B)

Typical Applications

• Optical power measurement in fiber-optic communication systems


• Optical component characterization (detectors, modulators, attenuators)


• Wavelength-dependent power analysis in the near-infrared band


• Multichannel lightwave system testing

Compatibility & Integration The 81634A is a plug-in module for Agilent/Keysight 816x mainframe systems. Operation requires an interface module (single or dual channel) and warm-up, zeroing, and auto-range configuration for specification validity.