Agilent/Keysight 81651A Optical Head

The Agilent/Keysight 81651A Optical Head is a Fabry-Perot laser diode source module for insertion loss, optical return loss, and PDL measurements of broadband components and fiber. Operating at 1550 nm with ±15 nm tolerance, it delivers > 0 dBm output power with exceptional short-term and long-term stability. The InGaAsP FP laser exhibits insensitivity to back reflections and broad spectral bandwidth, making it suitable for demanding optical characterization tasks.

– Technical Specifications

• Laser Type: Fabry-Perot laser diode (InGaAsP)
• Center Wavelength: 1550 nm (±15 nm tolerance)
• Spectral Bandwidth (rms): 0 dBm (1 mW)
• Fiber Type: Standard single-mode 9/125 µm
• Output Attenuation: 0 dB to 6 dB in 0.1 dB steps
• CW Power Stability (typical):
– Short-term (15 min): ±0.005 dB
– Long-term (24 h): ±0.03 dB
– To back reflection (RL ≥ 14 dB): ±0.03 dB
• Internal Digital Modulation: 270 Hz, 330 Hz, 1 kHz, 2 kHz, or user-selectable 200 Hz to 10 kHz with 50% duty cycle
• Coherence Control: Internal linewidth broadening available
• Dimensions: 75 mm × 32 mm × 335 mm
• Weight: 0.5 kg
• Operating Temperature: 0°C to +45°C
• Warm-up Time: 60 minutes (20 minutes if previously at same temperature)
• Recalibration Period: 2 years

– Key Features

• Class 1 laser per IEC 60825-1 (2001) and 21 CFR 1040.10 compliant
• Requires straight output connectors
• Insensitive to back reflections with stabilization for short- and long-term applications
• Wavelength displayed on instrument

– Typical Applications

• Insertion loss measurements of broadband components
• Optical return loss characterization
• Polarization Dependent Loss (PDL) assessment of fiber and components

– Compatibility & Integration

Designed for Agilent 8163A/B, 8164A/B, and 8166A/B lightwave measurement systems. Requires single (Keysight 81618A) or dual (Keysight 81619A) Interface Module for operation.