OTDR – Optical time-domain reflectometry

Lasers in OTDR (optical time-domain reflectometry)

An optical time-domain reflectometer (OTDR) is an optoelectronic instrument used to characterize, troubleshoot and maintain optical networks. OTDR testing is done by injecting a series of optical pulses into the fiber under test, and characterizing the scattered or reflected light.

The laser light pulse travels in the fiber and experiences reflections from defects, splices and connectors. The reflected light signal is directed to a sensitive photodetector, which is suitable for detecting the light emitted by the laser diode. As the speed at which the light propagates in the fiber is known as well as the time when the light pulse is sent into the fiber, the distance that the pulse has traveled can be calculated giving the position of defects in the fiber as well as the length of fiber.

An OTDR device contains a laser diode source, a photodiode detector and a highly accurate timing circuit (or time base). Lasers used in OTDR are commonly Fabry-Pérot (FP) type, sometimes Distributed Feedback (DFB). Wavelengths most commonly used are 1310 nm, 1490 nm, 1550 nm, 1625 nm, and 1650 nm.

Modulight has had inhouse laser design and production since year 2000. Combined with our industry-leading quality control and traceability we can serve even the most demanding laser customers. Our OTDR lasers are available as chips, TO-can lasers, or fiber-coupled modules. 

Thanks to our inhouse design and production we are able to customize laser chips and modules to meet customer-specific requirements. If you can’t find a perfect match from the below lists of our standard product, just contact us and let our engineering team design a tailored solution for you. Modulight vertically integrated approach allows us to provide lasers for most demanding applications within a short turnaround time.

Fiber-coupled OTDR laser modules

Lasers ready to use

Fiber-coupled coaxial or butterfly packaged laser modules are the easiest choice for OTDR equipment builders. Both package options are industry standard choices.

OTDR lasers in TO-can package

For fiber-coupling or free-space use

TO-56 is the go-to package for pulsed transmitter lasers such as the OTDR application requires. The laser beam output can be from a flat, aspherical or ball lens.

OTDR laser unmounted chips

Chips are great for customers building their own systems

As an original semiconductor laser manufacturer, Modulight can also provide OTDR lasers as unmounted bare die chips. We can also tailor you a custom laser if you need a different wavelength or otherwise different product.

Fiber-coupled OTDR lasers

Modulight has two alternative packages for fiber-pigtailed OTDR lasers; a coaxial pigtailed package with a tiny footprint, and a slightly larger but more versatile 14-pin butterfly package. The package details can be found from the datasheets, which you can access by clicking the link on the product code.

 

Product code ML5532-1310 ML5632-1310 ML5532-1490 ML5632-1550 ML5631-1625 ML5632-1625 ML1527
Package type Coaxial Butterfly Coaxial Butterfly Butterfly Butterfly Coaxial
Wavelength 1310 nm 1310 nm 1490 nm 1550 nm 1625 nm 1625 nm 1650 nm
Laser type FP FP FP FP DFB FP FP
Optical Output Power *) 180 mW 180 mW 70 mW 125 mW 80 mW 90 mW 30 mW

TO-can OTDR lasers

Modulight’s OTDR lasers are available in an industry standard package, a TO-56. Most products have a simple flat lens cap. The package details can be found from the datasheets, which you can access by clicking the link on the product code.

Product code ML1344 ML1925 ML1345 ML1979 ML1340 ML2184 ML1526
Lens type flat flat flat flat flat ball flat
Wavelength 1310 nm 1490 nm 1550 nm 1625 nm 1625 nm 1625 nm 1650 nm
Laser type FP FP FP FP FP FP FP
Optical Output Power *) 300 mW 180 mW 200 mW 150 mW 100 mW 100 mW

OTDR laser chips (bare die)

Although our most popular products in the OTDR range include the fiber-pigtailed and TO-can packaged lasers, Modulight can provide unmounted (bare die) chips for customers who prefer to do the mounting and packaging themselves.

 

Product code ML1003 ML1408 ML1954 ML1008 ML1409 ML1009 ML1411 ML1931 ML1525
Wavelength 1310 nm 1310 nm 1490 nm 1550 nm 1550 nm 1625 nm 1625 nm 1650 nm 1650 nm
Laser type FP FP FP FP FP FP FP DFB FP
Optical Output Power *) 300 mW 100 mW 180 mW 200 mW 100 mW 150 mW 100 mW 80 mW 100 mW

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