Crystal Fibre Ytterbium Double Clad Fiber Range

Actively doped double clad fibers is a group of very efficient brightness converting fibers. Such fibers are pumped by multimode diodes and provides lasing/amplification in a single mode. Traditionally, double clad fibers have been made as step-index fibers of different materials - most typically with a polymer outer cladding. With the PCF technology, the fibers can be made of all silica.

Double clad fibers made with photonic crystal fiber technology are known as air-clad fibers and provide a range of new benefits: The extremely high numerical aperature (NA) for the pump core/inner cladding is possible, allowing efficient pumping with inexpensive / high power broad area emitting pumps. The large mode area for the single mode signal facilitates high power levels while avoiding nonlinearities and providing a good overlap between the pump guide and the signal guide area (= high pump absorption, high efficiency). The fibers have efficient mode and ray scrambling even for circular pump cores and the all glass design has a much higher damage threshold than standard double-clad fibers.

Crystal Fibre Ytterbium Double Clad Fiber Range 
                  DC-70-11-PM-Yb DC-135-15-PM-Yb-01 DC-170-40-Yb-2 DC-200-40-PZ-Yb-01 DC-200-70-PM-Yb-ROD DC-200-85-Yb-ROD

Core size 11 ± 1 μm 15 ± 1 μm 40 ± 3 μm 40 ± 2 μm 70 ± 5 μm 85 ± 5 μm
Pump cladding diameter 70 ± 3 μm 135 ± 5 μm 170 ± 10 μm 200 ± 5 μm 200 ± 5 μm 200 ± 5 μm
Pump cladding geometry Circular Circular Circular Circular Circular Circular
Cladding diameter 170 ± 5 μm 280 ± 10 μm 620 ± 25 μm 450 ± 20 μm 1700 ± 100 μm 1700 ± 100 μm
Coating diameter 300 ± 20 μm 345 ± 20 μm 770 ± 30 μm 620 ± 30 μm NA NA
Coating material HT acrylate HT acrylate HT acrylate HT acrylate None None
Mode properties Single mode Single mode Single mode Single mode Single mode Single mode
MFD 12 ± 1 μm 16 ± 1 μm 30 ± 3 μm 29 ± 2 μm 55 ± 5 μm 65 ± 5 μm
Signal core NA @ 1 μm 0.08 ± 0.005 0.055 ± 0.01 ~0.03 ~0.03 ~ 0.02 ~ 0.02
Fiber format Flexible Flexible Flexible Flexible Rod Rod
Min bending radius 10 cm 10 cm 40 cm 30 cm NA NA
Pump absorption @ 976 nm ~ 4 dB/m 2.8 dB/m ~ 13 dB/m ~10 dB/m ~ 30 dB/m ~ 30 dB/m
Pump absorption @ 915 nm ~ 12 dB/m ~8 dB/m ~ 4.5 dB/m ~3 dB/m ~ 10 dB/m ~ 10 dB/m
Pump NA @ 950 nm 0.63 ± 0.03 0.6 ± 0.05 0.62 ± 0.05 0.55 ± 0.05 0.6 ± 0.05 0.54 ± 0.05
PER db > 17 dB > 18 dB Non-PM > 15 dB > 15-25 dB Non-PM
Birefringence > 1.0·10-4 1.3·10-4 Non-PM > 1·10-4 > 1·10-4 Non-PM

Advantages of the fibers, are:

High peak power levels
High pulse energy while single mode
High pump NA (0.6-0.7)
High pump absorption (up to 30 dB/m)
Short fiber lengths
All-glass design - no polymers - for excellent power handling
Good thermal properties
High reliability