FiberLert Live Fiber Detector

Dec. 14, 2022
Fluke Networks' Live Fiber Detector is a pocket-sized tester that detects invisible near-infrared wavelengths used in fiber optic communications.

2022 NED Innovation Award Finalist

The FiberLert Live Fiber Detector is a pocket-sized tester that detects invisible near-infrared (850 to 1625 nm) wavelengths used in fiber optic communications. When placed in front of an active fiber optic port or patch cord, the tester emits a continuous light and optional tone. Unlike more complex testers, the FiberLert requires no setup or interpretation of measurement readings on the part of the user.


FiberLert removes the guesswork by clearly indicating where the signal is present and where it is not. This allows users to quickly pinpoint and remedy the cause of the problem, such as a failed transceiver or failed patch cord. FiberLert supports single-mode, multimode, UPC/APC patch cords and ports and can test without contacting the port or patch cord, reducing the risk of contamination or damage.


FiberLert’s LightBeat feature flashes the LED, indicating a powered-on condition and good battery. A timer shuts the tester off after five minutes of inactivity to extend battery life. The rugged design includes a convenient pocket clip and is backed by a two-year warranty.

  • Detects optical power in single-mode and multimode fiber wavelengths (near infrared range 850 to 1625 nm)
  • No setup or interpretation is needed—light and sound indicate the presence of an optical signal
  • Non-contact detector reduces the risk of contamination and damage
  • Suitable for ports and patch cords, SM, MM, UPC, and APC connections
  • LightBeat flashes to indicate operation and battery status; powers off after five minutes of inactivity to preserve battery life (2xAAA, included)
  • Two-year warranty
Operating PrincipleSenses near-infrared light emitted from fiber optic cabling.
A continuous red glow at the handle and an audible beeping noise
(if not switched off) indicates the presence of near-infrared light.Optical InterfaceNon-contact ceramic ferrule.
Fits directly with 0.05 in. (1.25 mm) LC receptacles.
Tethered ferrule adapter for testing 0.05 in.(1.25 mm)
ferrule patch cord.
Supports single, multimode, UPC, and APC connectors and ports.Wavelength Detection850 to 1625 nmOptical Power Detection Range+3 dBm to -30 dBmLight DetectionRed LED indicator when optical power is detectedLightBeat IndicatorFlashes twice every two seconds
when on and battery strength is sufficientBatter SaverAutomatically turns off after 5 minutes of inactivityBatteries2 AAA alkaline batteries includedBattery LifeTypically, greater than 1 year (5 hrs. of use a week)Size0.6 x 1.0 x 6.6 in. (1.6 x 2.5 x 16.8 cm)Weight59 g (2.1 oz)Operating Temp. Range14 to 122°F (-10 to 50°C)Operating Humidity Range95% (50 to 95°F (10 to 35°C))
Non-condensing 75% (95 to 104°F (35 to 40°C)
Non-condensing uncontrolled < 50°F (10°C)Operating Altitude?  1.8 miles (3,000 m)Storage Temp. -4 to 122°F (-20 to 50°C)