81531A

Keysight Technologies (Agilent HP)Optical

The Keysight (Agilent/HP) 81531A is an InGaAs-based optical power sensor module designed for use with the HP 8153A Lightwave Multimeter mainframe. It provides high-sensitivity power measurements across a wide wavelength range of 800 to 1700 nm, making it suitable for standard single-mode and multimode optical fiber testing.

Fiber Optics Lightwave Measurement

Specifications

General

Parameter	Value
Interfaces	HP 8153A proprietary backplane interface
Display	None (uses mainframe display)

Physical

Parameter	Value
Power Supply	Powered by host HP 8153A mainframe
Operating Temperature	0 °C to +55 °C
Dimensions (W×H×D)	32 mm × 75 mm × 335 mm
Weight	0.5 kg

Optical Characteristics

Parameter	Value
Wavelength Range	800 to 1700 nm
Detector Material Type	InGaAs
Power Measurement Range	+3 to -90 dBm

Measurement Accuracy and Linearity

Parameter	Value
Noise Floor (Equivalent Noise Power)	< 1.5 pW peak-to-peak (1200 to 1600 nm, 1 s averaging time)

Optical Interface and Connectivity

Parameter	Value
Compatible Fiber Types	9/125 µm to 100/140 µm
Maximum Acceptance Angle / Numerical Aperture (NA)	≤ 0.3
Supported Connector Adapters	HP 81000 series connector adapters (FC, SC, ST, DIN, etc.)
Connection Interface to Host Mainframe	HP 8153A Lightwave Multimeter slot

Physical and Mechanical Specifications

Parameter	Value
Form Factor	Plug-in module
Host Slot Occupancy	1 slot

Optical Specifications

Parameter	Value
Sensor Diameter	1 mm
Maximum Input Power	+10 dBm
Calibration Uncertainty	±2.5% (at 1300 nm / 1550 nm, reference conditions)
Linearity	±0.02 dB (+3 to -70 dBm)

Environmental

Parameter	Value
Storage Temperature	-40 °C to +70 °C
Operating Humidity	95% R.H. max @ 40 °C (non-condensing)

Performance

Parameter	Value
Polarization Dependence	< ±0.01 dB (typical @ 1310 nm and 1550 nm)
Warm-up Time	40 min
Averaging Time Range	20 ms to 3600 s (mainframe controlled)

Technology

InGaAs Optical Power Sensor

Applications

Optical power measurement and fiber optic testing