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82140 Olching / Germany

Phone: +49 (0)8142 / 28 64-0
Fax: +49 (0)8142 / 28 64-11



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Photonics News No 76

Reading our company newsletter, Photonics News, keeps you up to date. All technological and product news, as well as current information about LASER COMPONENTS, is available in concentrated form.

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The Mode Specialist - Arden Photonics


Arden Photonics develops and manufactures components and measurement devices for optical fibers and lasers. The company was founded in the West Midlands in England in 2001, which helps explain the origin of the company’s name:
The name Arden comes from the Forest of Arden, an old oak forest that once spanned a large area in Central England, including Stratford-upon-Avon, the birthplace of William Shakespeare.
Its founder, David Robinson, is still the general manager of the company, which is located in Solihull, south of Birmingham.

Mode Controllers and Mode Meters
With Arden Photonics’ mode controllers, measurements can be guaranteed according to encircled flux conditions.  The meters test the mode distribution in the fibers and ensure standard reproducible measurements.

Reproducible Measurements according to Encircled Flux

DIN EN 61280-4-1:2009 Standard in the Attenuation Measurement of Multi-mode Fibers
Local fiber optic networks feature high data rates: The increased demands of IP-based data transmission will in the future require bandwidths of up to 10 gigabits and higher. Internet TV, online music services, and SmartHome applications are only some of the drivers of this development. The high data volume can be covered by implementing multi-mode fibers (MMFs). To control their transmission quality, the attenuation must be identified precisely and reproducibly. This initially requires meters that conform to the DIN61280-4-1 norm; they must also conform to the encircled flux conditions.

Underfill, Overfill

The coupling conditions in MMFs significantly influence both attenuation and bandwidth: The excitation conditions vary, including underfill, overfill, and encircled flux.
Underfill. When coupling a laser (or VCSEL), large core diameters lead to so-called “underfill”: The core is not completely illuminated, and the attenuation appears lower than it actually is.
Overfill. The opposite occurs when light is coupled by an LED. The beam diameter is larger; not all of the power can be coupled into the fiber core. This leads to “overfill.”

Encircled Flux – Measuring Reproducibly
The encircled flux (EF) parameter was introduced in order to define the fill state of MM fibers during coupling. This is standardized as part of the IEC61280-4-1 norm and defines coupling conditions in relation to the power in the fiber core. Such defined conditions include the radial size of the coupling area and the angular distribution.
The ratio of the transmitted power at a given radius of the fiber core to the absolute coupled power is defined as the EF parameter.

Conformity of Measurement Standards
Mode controllers can be used to ensure conformity of measurement standards. The controller is a passive fiber optic component that guarantees excitation conditions according to the norm – irrespective of the light source used (LED or laser). It is inserted either between the source and the fiber to be measured (LSPM) or after the launch fiber in OTDR measurements. Both standard telecom MM fibers (50 µm and 62.5 µm) have their own controllers.

Encircled Flux Measurements
To date, encircled flux measurements for mode determination have only been carried out in the laboratory. Meters such as the MPX are used for this purpose. Anybody who assembles or manufactures fiber optic cables should use a meter for mode determination to test the quality of his products. “Encircled flux” measurements can be performed in the field using mode controllers.

Further product information:
Mode Controller

Arden Photonics Ltd


Contact Person:    Dr. Andreas Hornsteiner
Address:    Werner-von-Siemens-Str. 15
ZIP / City:    82140 Olching
Phone:    +49 (0) 8142 2864-82
Fax:    +49 (0) 8142 2864-11

MPX Modal Explorer

Measuring Station for Encircled Flux

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Your contact person

Claudia Michalke

+49 (0) 8142 2864-85