Multimode Fiber Cables MMC

for UV/VIS or VIS/NIR

FC-APC-3
FC-APC-1
Representative product images. Individual product images are found on the individual product pages.
Multi-mode fiberMulti-
Mode

Features

Multimode fiber cable with customer-specified fiber connectors.
  • Wavelength ranges UV/VIS or VIS/NIR
  • Core diameters 50 µm - 300 µm
  • Fiber patch cable available with buffer or as Ø 3 mm cable with Kevlar strain-relief
  • Customer-specified connectors type FC, DIN or AVIO, E2000, ST (only 0°-polish), or F-SMA (only 0°-polish) with  0°-polish or 8°-polish
  • Amagnetic titanium connectors for connectors of type FC PC or FC APC

Description

Multimode fiber cable with customer-specified fiber connectors.

Fiber
The multimode fibers are either graded (gradient index, GRIN) index or step index fibers with an NA specified by the fiber manufacturer. Schäfter+Kirchhoff offer pure silica core fibers with core diameter is 50 µm - 600 µm. There are fibers suitable for either the wavelength range UV/VIS or for the wavelength range VIS/NIR.

Fiber Cable
All fiber lengths can be customer specified. The multimode fiber cables are offered with buffer in black, or a Ø 3 mm cable in black with Kevlar strain-relief.

Fiber Connectors
For each fiber end the fiber connectors can be selected from a wide range of connector types (FC, DIN or AVIO, E2000, ST (only 0°-polish), or SMA-905 (F-SMA) (only 0°-polish) with 0°-polish or 8°-polish. All fiber connectors of type FC assembled by Schäfter+Kirchhoff have an alignment index (key). The wide key (type "N") fiber connector has an alignment index (key) of 2.14 mm width. The narrow key (type "R") fiber connector has an alignment index (key) of 2 mm width. Special fiber connectors are available so that the fiber cable is vaccum compatible down to 10-7 mbar (only Ø 900 µm buffer fiber cables).

Amagnetic fiber connectors
For FC PC or FC APC type connectors amagnetic versions completely made of titanium can be selected. Those connectors have a ceramic ferrule. The relative permeability µr of the connector is near 1 (χ = 5·10- 5, µr = 1.00005), making it transparent to magnetic fields.

Order Options

  TypeCore DiameterWavelength RangeNumerical ApertureSuitable for Vacuum Feed-throughs
MMC-S-UV/VIS-50-NA022Step index50 µmUV - VIS0.22x
MMC-S-VIS/NIR-50-NA022Step index50 µmVIS - NIR0.22x
MMC-G-VIS/NIR-50-NA020Graded index50 µmVIS - NIR0.20x
MMC-S-VIS/NIR-62.5-NA027Graded index62.5 µmVIS - NIR0.27x
MMC-S-UV//VIS-105-NA022Step index105 µmUV - VIS0.22x
MMC-S-VIS/NIR-105-NA022Step index105 µmVIS - NIR0.22x
MMC-S-UV//VIS-200-NA022Step index200 µmUV - VIS0.22 
MMC-S-VIS/NIR-200-NA022Step index200 µmVIS - NIR0.22 
MMC-S-VIS/NIR-300-NA022Step index300 µmVIS - NIR0.22 
MMC-S-UV/VIS-400-NA022Step index400 µmUV - VIS0.22 
MMC-S-VIS/NIR-400-NA022Step index400 µmVIS - NIR0.22 
MMC-S-UV/VIS-600-NA022Step index600 µmUV - VIS0.22 
MMC-S-VIS/NIR-600-NA022Step index600 µmVIS - NIR0.22 
          
For a complete Order Code additional information such as cable type, cable length, and connector type are necessary. Please contact us.         

FAQ

  • Connector Type FC PC and FC APC
    • How do I attach a fiber cable?

      1. To prevent damage to the sensitive fiber end-face, always insert the fiber connector`s ferrule at an angle, with the connector key properly aligned to the receptacle notch.
      2. When the ferrule tip is safely located in the inner cylinder of the receptacle, align the connector to the receptacle axis and carefully introduce the connector into the fiber coupler.
      3. Then, orient the connector key in a way that it is pressed gently onto the right-hand side of the receptacle notch ("right-hand orientation rule").
      4. Gently screw on the connector cap nut onto the receptacle until it is finger-tight.
      5. Gently tighten the fiber grub screw to reduce the free play of the ferrule in the receptacle.

    • What is the "right-hand orientation rule"?

      When the ferrule tip is safely located in the inner cylinder of the receptacle, align the connector to the receptacle axis and carefully introduce the connector into the fiber coupler. 

      Then, orient the connector key in a way that it is pressed gently onto the right-hand side of the receptacle notch.

      The tightened grub screw and the "right-hand orientation rule" for the connector, ensure a high reproducibility in mode field position and angle, which is especially important for attaching and reattaching polarization-maintaining fibers reproducibly.

    • Can I attach a narrow key fiber cable to a fiber coupler with a wide key receptacle?

      Yes, you can- without any problem. Simply adhere to the "right-hand orientation rule".

      Generally, with any FC PC or FC APC type connector there is a freeplay when inserting the fiber into the fiber coupler. The free play in between the connector ferrule and receptacle is only a few microns, but necessary for inserting the ferrule without force. There is a difference between the receptable and key width for wide key (2.14 mm) and narrow key (2.0 mm) fibers. If you follow the so-called "right-hand orientation rule" you can reproducibly attach and reattach even PM fibers with narrow key receptacle to fiber couplers with wide key receptacle without difficulty.

      "Right-hand orientation rule":

      When the ferrule tip is safely located in the inner cylinder of the receptacle, align the connector to the receptacle axis and carefully introduce the connector into the fiber coupler. Then, orient the connector key in a way that it is pressed gently onto the right-hand side of the receptacle notch. The tightened grub screw and the "right-hand orientation rule" for the connector, ensure a high reproducibility in mode field position and angle, which is especially important for attaching and reattaching polarization-maintaining fibers reproducibly.


    • Can I use an end cap fiber with a mating sleeve?
      Since the radiation has already started to diverge within the end cap, a simple mating is no longer possible. Please use a fiber-to-fiber coupler in this case.
  • What is the minimum bend radius for my fiber cable?
    • Do you have a Ø 900 µm cable?
      If yes, then the min. bend radius is 15 mm. More information can be found here.
    • Do you have a Ø 3 mm cable?
      If yes, then the min. bend radius is 40 mm. More information can be found in the drawing here.
  • Multimode fiber coupling
    • Why does my beam profile change when I touch the fiber?

      The beam profile exiting a multimode fiber is strongly dependent on how the light interacts within the fiber and is often very different from that of a single-mode fiber - it might even change with time and fiber position. For a good, symmetric, and “super-Gaussian” distribution of light exiting the multimode fiber (aside from laser speckle), it is important that mode mixing has occurred within the fiber or that multiple modes have been excited from the start when coupling in.

      For example, if you couple light into the fiber from a single-mode laser source, only a few modes will be excited. If you then change the fiber position or touch the fiber, the ex-fiber beam profile can change rapidly over time because different modes are excited that may not have a symmetric, Gaussian-like output (e.g. donut modes).
       
      To avoid this, you can either make the multimode fiber longer (to increase mode mixing as it passes through the fiber) or coil the fiber with a smaller bend radius to increase mode mixing. You can also choose a smaller focal length to have a larger light cone when coupling into the fiber, which in turn excites more modes. Often a combination of these three strategies will result in a stable, “super-Gaussian” beam profile exiting the multimode fiber.

    • Why does my beam profile look non-Gaussian?
      The beam profile exiting a multimode fiber is strongly dependent on how the light interacts within the fiber and is often very different from that of a single-mode fiber - it might even change with time and fiber position. For a good, symmetric, and “super-Gaussian” distribution of light exiting the multimode fiber (aside from laser speckle), it is important that mode mixing has occurred within the fiber or that multiple modes have been excited from the start when coupling in.

      For example, if you couple light into the fiber from a single-mode laser source, only a few modes will be excited. If you then change the fiber position or touch the fiber, the ex-fiber beam profile can change rapidly over time because different modes are excited that may not have a symmetric, Gaussian-like output (e.g. donut modes).

       To avoid this, you can either make the multimode fiber longer (to increase mode mixing as it passes through the fiber) or coil the fiber with a smaller bend radius to increase mode mixing. You can also choose a smaller focal length to have a larger light cone when coupling into the fiber, which in turn excites more modes. Often a combination of these three strategies will result in a stable, “super-Gaussian” beam profile exiting the multimode fiber.