Agilent/Keysight 81553SM High Power Singlemode Optical Head

The Agilent/Keysight 81553SM is a single-mode optical head module for precise optical power measurements in fiber optic systems. Built on Fabry-Perot laser technology, it delivers stable 1550 nm output suitable for testing and characterizing optical components and networks. The module integrates directly into Agilent/Keysight 8153A, 8163A, 8164A, and 8166A lightwave mainframes.

Technical Specifications

• Laser Type: Fabry-Perot, InGaAs


• Central Wavelength: 1550 nm ± 20 nm


• Output Power: Greater than 0 dBm


• Spectral Bandwidth: Less than 4 nm RMS


• Fiber Type: 9/125 µm single-mode


• Output Attenuation: 0 dB to 6 dB, adjustable in 0.1 dB steps


• Long-term CW Stability: ± 0.003 dB (after 20 minute warm-up)


• Internal Modulation Frequencies: 270 Hz, 1 kHz, 2 kHz (50% duty cycle)


• Analog Output Bandwidth: DC to <300 Hz (expandable to 1000 Hz depending on range)


• Analog Output Voltage: 0–2 V into open circuit


• Output Impedance: 600 Ω typical


• Maximum Input Voltage: ±10 V

Key Features

• Internally adjustable attenuation with 0.1 dB resolution enables precise signal conditioning across a 6 dB range


• Multiple modulation frequencies support flexible test protocols and component characterization


• Long-term stability of ± 0.003 dB ensures repeatable measurements in production and field environments


• Proprietary module interface provides direct connection to Agilent/Keysight lightwave platforms

Typical Applications

• Optical power measurement and characterization


• Fiber optic component testing


• Optical network validation and troubleshooting


• Signal conditioning for optical measurement systems

Compatibility & Integration Designed for Agilent/Keysight 8153A, 8163A, 8164A, and 8166A lightwave mainframes. Requires a separately ordered 81000xI connector interface. Optimal performance achieved after 20 minute warm-up period.