Agilent/Keysight 81650A High Power Optical Head

The Keysight 81650A is a single-wavelength Fabry-Perot laser source module engineered for insertion loss, optical return loss, and polarization dependent loss (PDL) measurements of broadband components and fiber. Operating at 1310 nm with exceptional back-reflection insensitivity and stabilized output across short and long-term measurement intervals, this module integrates into compatible Keysight Lightwave mainframe systems to deliver precise optical characterization capabilities.

Technical Specifications

• Fabry-Perot laser diode at 1310 nm center wavelength


• Wavelength tolerance: ±15 nm


• Spectral width (rms): 0 dBm (1 mW minimum), maximum CW 15.6 mW


• Output attenuation: adjustable 0 dB to 6 dB in 0.1 dB steps Stability & Control


• Short-term power stability (15 min): < ±0.005 dB typ


• Long-term power stability (24 h): ±0.03 dB typ


• Back-reflection insensitivity (RL ≥ 14 dB): ±0.003 dB typ


• Internal coherence control for linewidth broadening


• Digital modulation: 270 Hz, 330 Hz, 1 kHz, 2 kHz, and 200 kHz to 10 kHz (50% duty cycle) Optical Interface


• Single-mode fiber: 9/125 µm


• Output connector: straight contact Physical Characteristics


• Dimensions: 75 mm (H) × 32 mm (W) × 335 mm (D)


• Weight: 0.5 kg


• Warm-up time: 60 minutes (20 minutes if stored at same temperature)

Key Features

• Back-reflection insensitivity enables measurements without optical isolators in many applications


• Dual-timescale stability supports both dynamic and static characterization


• Adjustable output power extends measurement dynamic range


• Internal modulation sources simplify test setups for coherence and linewidth studies

Typical Applications

• Component insertion loss characterization


• Optical return loss (ORL) measurement


• Polarization dependent loss (PDL) analysis


• Broadband fiber and component evaluation

Compatibility & Integration The 81650A operates exclusively as a plug-in module within these Keysight mainframe systems:

8163A/B Lightwave Multimeter

8164A/B Lightwave Measurement System

8166A/B Lightwave Multichannel System Use with optical power meter modules for complete measurement solutions. Operating temperature: 0°C to +45°C; storage: -40°C to +70°C. Class 1 laser per IEC 60825-1 and FDA CFR 21.