Agilent/Keysight 81635A Optical Channel Analyzer

The Agilent/Keysight 81635A is a dual-channel optical power sensor module for precision optical power measurements across communication and test environments. It houses two InGaAs detector channels in a single-slot 816x Lightwave mainframe module, supporting parallel multichannel measurements without external rack space penalties. The 81635A delivers absolute power measurements from +10 dBm to −80 dBm with ±3% uncertainty across the 800 nm to 1650 nm wavelength band, making it suitable for broadband and wavelength-division multiplexed system characterization.

Technical Specifications

• Dual InGaAs detectors, 2 independent channels


• Wavelength range: 800 nm to 1650 nm


• Power measurement range: +10 dBm to −80 dBm


• Power uncertainty: ±3%


• Polarization dependence: <±0.015 dB


• Fiber compatibility: Standard single-mode and multi-mode fibers up to 62.5 µm core; NA ≤0.24/0.3 depending on model variant


• Data logging capacity: 20,000 samples maximum


• Averaging time: Minimum 100 µs


• Analog output: 0 to 2 V proportional to optical signal strength (2 V at full input power)


• Front-panel BNC connector for analog output

Key Features

• Dual-channel simultaneous measurements in a compact single-slot form factor


• Hardware trigger lines and event triggering for synchronized data acquisition


• Triggered synchronization with tunable laser modules for spectral measurement capability


• Autoranging support with option to disable for fixed-reference analog output consistency


• Real-time data logging with minimum/maximum value recording and stability monitoring


• Configurable sampling and hardware timer integration for external control schemes

Typical Applications Optical power trending and stability analysis, spectral characterization via swept tunable laser sources, dual-channel comparative measurements, and long-term monitoring with automated event logging and triggering.

Compatibility & Integration All Keysight 816x series Lightwave mainframes. Requires Agilent 81618A (single module) or 81619A (dual module) Interface Modules. Accepts standard single-mode and multi-mode fibers through Agilent/Keysight flexible connector adapters or bare-fiber adapters.