HP 81534A Return Loss Module

The HP 81534A Return Loss Module is a precision optical instrument for measuring reflected power in fiber optic systems across the 1250 nm to 1600 nm window. It combines an InGaAs detector with an integrated directional coupler to isolate and quantify return loss from single reflections and multi-point reflection sources. The module operates with 9/125 µm single-mode fiber and delivers dynamic range up to 60 dB at 0 dBm source power—extendable beyond 65 dB with Option 001 pigtail output. Total measurement uncertainty reaches ±0.40 dB across 0–50 dB and ±0.65 dB from 50–60 dB, with relative uncertainty of ±0.25 dB and ±0.50 dB respectively.

– Technical Specifications

• Sensor Element: InGaAs
• Wavelength Range: 1250 nm to 1600 nm
• Applicable Fiber: 9/125 µm single-mode
• Dynamic Range: Up to 60 dB (0 dBm source); >65 dB with Option 001
• Total Uncertainty: ±0.40 dB (0–50 dB), ±0.65 dB (50–60 dB)
• Relative Uncertainty: ±0.25 dB (0–50 dB), ±0.50 dB (50–60 dB)
• Operating Temperature: 0 °C to +55 °C
• Recalibration Interval: 1 year
• Warm-up Time: 5 minutes
• Dimensions: 75 mm H × 32 mm W × 335 mm D
• Weight: 0.6 kg

– Key Features

• Directional coupler isolates reverse-traveling light for accurate reflected power measurement
• Sensitive integrated detector captures milliwatt-level and lower power signals
• Requires external light source, typically provided by compatible mainframe
• Calibration reference available via HP 81000BR or cleaved fiber end for pigtailed components
• Option 001 extends measurement range for pigtail-terminated devices

– Typical Applications

Return loss characterization of connectors, splices, filters, multiplexers, cross-connects, and optical amplifiers. Suited for single-mode systems in telecommunications, R&D, and production environments where signal integrity assessment is critical.

– Compatibility & Integration

Plugs directly into HP 8153A, 8163A, 8164A, and 8166A mainframes. Uses standard Agilent optical interface connectors (sold separately).