EXFO LFD-100 Live Fiber Detector

The EXFO LFD-100 Live Fiber Detector is a portable instrument that identifies active optical fibers without cable disconnection, enabling safe fiber identification during network maintenance and installation. Using a non-intrusive macrobending technique, it detects live and dark fibers across singlemode and multimode architectures while preserving signal integrity and preventing fiber stress. The instrument provides absolute or relative power readings, signal direction indication, and signal type classification - distinguishing customer traffic from continuous or modulated test signals at 270 Hz, 1 kHz, or 2 kHz.

Technical Specifications

• Fiber Compatibility: Singlemode and multimode fibers; supports 250 µm, 900 µm, and 3 mm jacket sizes; detects signals on fibers 4–9 of 12-fiber ribbon cables


• Power Measurement: Absolute or relative readings in dBm or dB; 0.1 dB display resolution above −50 dBm; absolute core power accuracy ±2 dBm


• Signal Detection: Identifies signal presence, type (customer traffic, continuous, modulated), and direction


• Test Methodology: Macrobending detection with low insertion loss; non-disruptive to live network traffic


• Display & Operation: Back-light toggle via 3-second dBm/ref button press; auto-off after 5 minutes inactivity or 10 seconds after failed self-test


• Power Source: Standard 9V alkaline battery; 8–10 hour runtime; low battery indicator


• Physical: 24 × 6.4 × 2.5 cm; 0.32 kg (with battery); 0.9 kg shipping weight


• Environment: Operating temperature −10° to 50°C; storage −40° to 60°C; 0–95% humidity (non-condensing)

Key Features

• Universal adjustable clamping head accommodates fiber sizes from 250 µm to 3 mm without tool changeover


• Non-removable head design ensures consistent, safe macrobending contact


• Distinguishes modulated test signals at three discrete frequencies: 270 Hz, 1 kHz, 2 kHz


• Delivers 0.1 dB resolution for precision splice and connector alignment verification

Typical Applications

• Cable labeling verification


• Continuity testing on dark fiber routes


• Pre-rerouting signal presence confirmation

Compatibility & Integration Works with standard singlemode and multimode patchcords, color-coated fibers, and 12-fiber ribbon cables. Universal head design eliminates adapter requirements across diverse fiber geometries.