HP / Agilent 81657A Dual Fabry-Perot Laser Source, 1310nm & 1550nm

The HP/Agilent 81657A is a dual-wavelength Fabry-Perot laser source delivering stable, back-reflection-insensitive output at 1310 nm and 1550 nm. Operating at up to +13 dBm per channel with ±0.03 dB power stability over 24 hours, it performs insertion loss, optical return loss, and polarization-dependent loss measurements across fiber optic communication systems. The source couples to standard single-mode 9/125 µm fiber and integrates with Agilent 8163/8164/8166 series mainframes via separate optical interface connectors. Internal digital modulation modes span 270 Hz to 10 kHz with programmable 0–6 dB attenuation in 0.1 dB steps.

Technical Specifications

Wavelengths: 1310 nm (±15 nm), 1550 nm (±15 nm)

Output Power: +13 dBm per channel (≈20 mW); maximum permissible CW output 52 mW

Power Stability: ±0.03 dB over 24 hours; ±0.005 dB over 15 minutes

Spectral Bandwidth (rms): <5.5 nm at 1310 nm; <7.5 nm at 1550 nm

Fiber Interface: Single-mode 9/125 µm; beam waist 9 µm; numerical aperture 0.1

Attenuation Range: 0–6 dB in 0.1 dB increments

Modulation Modes: Internal digital at 270 Hz, 330 Hz, 1 kHz, 2 kHz; free selection 200 kHz–10 kHz; 50% duty cycle

Laser Classification: Class 1M (IEC 60825-1:2001); Class IIIb (21 CFR 1040.10); Class 3A (IEC 60825-1:1998)

Key Features

Back-reflection immune operation ensures measurement stability without external isolation

Dual-channel architecture eliminates need for multiple sources in 1310/1550 nm test suites

Internal coherence control enables linewidth broadening for PDL characterization

Programmable pulse modulation with shaped outputs

Fault-triggered optical shutoff via internal safety circuitry

Typical Applications

Component insertion loss and return loss measurement

Polarization-dependent loss (PDL) characterization

Optical system-level performance validation

Wavelength-dependent attenuation testing

Compatibility & Integration Designed for use with Agilent 8163A/B, 8164A/B, and 8166A/B mainframes. Requires Agilent 81000xI series optical interface connectors (sold separately). Integrates with optical power meter modules for complete test solutions.