for UV/VIS or VIS/NIR
Multi-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.
| Type | Core Diameter | Wavelength Range | Numerical Aperture | Suitable for Vacuum Feed-throughs | |
|---|---|---|---|---|---|
| MMC-S-UV/VIS-50-NA022 | Step index | 50 µm | UV - VIS | 0.22 | x |
| MMC-S-VIS/NIR-50-NA022 | Step index | 50 µm | VIS - NIR | 0.22 | x |
| MMC-G-VIS/NIR-50-NA020 | Graded index | 50 µm | VIS - NIR | 0.20 | x |
| MMC-S-VIS/NIR-62.5-NA027 | Graded index | 62.5 µm | VIS - NIR | 0.27 | x |
| MMC-S-UV//VIS-105-NA022 | Step index | 105 µm | UV - VIS | 0.22 | x |
| MMC-S-VIS/NIR-105-NA022 | Step index | 105 µm | VIS - NIR | 0.22 | x |
| MMC-S-UV//VIS-200-NA022 | Step index | 200 µm | UV - VIS | 0.22 | |
| MMC-S-VIS/NIR-200-NA022 | Step index | 200 µm | VIS - NIR | 0.22 | |
| MMC-S-VIS/NIR-300-NA022 | Step index | 300 µm | VIS - NIR | 0.22 | |
| MMC-S-UV/VIS-400-NA022 | Step index | 400 µm | UV - VIS | 0.22 | |
| MMC-S-VIS/NIR-400-NA022 | Step index | 400 µm | VIS - NIR | 0.22 | |
| MMC-S-UV/VIS-600-NA022 | Step index | 600 µm | UV - VIS | 0.22 | |
| MMC-S-VIS/NIR-600-NA022 | Step index | 600 µm | VIS - NIR | 0.22 | |
| For a complete Order Code additional information such as cable type, cable length, and connector type are necessary. Please contact us. | |||||
Typical Spectra, graded vs step index, etc.
Selection of focal length
Collimated beam diameter and divergence
Calculation of spot diameter
Details on the structure of 3 mm and 900 µm fiber cables.
FC, AVIM and E2000
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.
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.
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.
Polarization-maintaining fiber cables
Single-mode fiber cables
Fiber Coupler for multi-mode fiber cables.
Fiber Collimators for collimating light exiting a multi-mode fiber cable
