Agilent / Keysight 81940A 1520-1630nm Tunable Laser Source

The Keysight 81940A is a compact tunable laser source operating across 1520–1630 nm, delivering precise optical stimulus for component and system characterization. This module integrates a built-in wavemeter, coherence control, and SBS suppression to enable low-uncertainty measurements across the C and L bands with mode-hop-free tuning, high output power, and exceptional wavelength stability. Designed for modular integration with 8163A/B, 8164A/B, and 8166A/B mainframe systems, it excels in testing optical amplifiers, DWDM devices, and both active and passive optical components.

Technical Specifications

• Wavelength Range: 1520 nm to 1630 nm (110 nm total tuning range)


• Wavelength Resolution: 1 pm; 125 MHz at 1550 nm


• Mode-Hop-Free Tuning: Full wavelength range


• Sweep Speed: 50 nm/s maximum


• Absolute Wavelength Accuracy: ±20 pm (typical ±5 pm)


• Relative Wavelength Accuracy: ±10 pm (typical ±5 pm)


• Wavelength Repeatability: ±2.5 pm (typical ±1 pm)


• Wavelength Stability (24 h): ±2.5 pm


• Linewidth: >50 MHz (1570–1620 nm, coherence control off); 100 kHz effective (coherence control on)


• Output Power: ≥+14.5 dBm peak (typical); ≥+13 dBm (1570–1620 nm); ≥+10 dBm (full range)


• Power Linearity: ±0.1 dB


• Power Stability: ±0.01 dB over 1 hour (typical); ±0.03 dB over 24 hours


• Power Flatness vs. Wavelength: ±0.2 dB (typical ±0.1 dB) across 1570–1620 nm; ±0.3 dB (typical ±0.15 dB) full range

Key Features

• Built-in wavemeter for direct wavelength measurement and reduced calibration uncertainty


• Coherence control to suppress stimulated Brillouin scattering and cavity-induced interference


• Continuous sweep mode enabling repeatable, mode-hop-free operation across all bands


• High output power sufficient for direct amplifier stimulus without external boosters

Typical Applications Optical amplifier characterization, DWDM component testing, wavelength-dependent device response measurement, and multiband optical system validation.

Compatibility & Integration Pluggable module for Keysight 8163A/B, 8164A/B, and 8166A/B optical instrument mainframes.