Double clad ytterbium fibers made with photonic crystal fiber technology are known as air-clad fibers and provide a range of new benefits: The extremely high numerical aperture (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.
Features
- Single-mode with large mode area
- Handles high peak power and pulse energy
- High NA circular pump core
- High pump absorption with no skew-rays
- All-glass design – no polymers – for excellent power handling
- High reliability
Flexible fibers
- DC-135/14-PM-Yb
- DC-200/40-PZ-Yb
Gain modules
Flexible fibers
| DC-135/14-PM-Yb | DC-200/40-PZ-Yb | |
| Signal core | ||
| Mode properties | Single-mode | Single-mode |
| Cut-off [nm] | ≤ 1000 | See White Paper |
| Beam quality (typical) @ 1064 nm | M2 ≤ 1.3 | M2 ≤ 1.3 |
| Mode-field diameter, 1/e2 @ 1064 nm [µm] | 15 ± 1 | 31 ± 2 |
| Multi-mode pump core | ||
| Pump absorption @ 915 nm [dB/m] | 2.30 ± 0.35 | 3.75 ± 0.75 |
| Pump absorption @ 976 nm, typical [dB/m] | ≈ 7 | ≈ 10 |
| Polarization parameters | ||
| Birefringence Δn @ 1100 nm, typical | ≥ 1 x 10-4 | ≥ 1 x 10-4 |
| PER, typical @ 1064 nm [dB] | ≥ 15 | ≥ 15 |
| Physical properties | ||
| Signal core diameter [µm] | ≈ 14 | ≈ 40 |
| Pump cladding diameter [µm] | 135 ± 3 | 200 ± 3 |
| Outer cladding diameter [µm] | 275 ± 8 | 450 ± 20 |
| Coating diameter [µm] | 360 ± 15 | 540 ± 30 |
| Coating material, single-layer | High-temperature acrylate | High-temperature acrylate |
| Outer and pump cladding material | Pure silica | Pure silica |
The Single-Mode Advantage
All our fibers are single-mode leading to several advantages compared to standard multimode LMA fibers:
- Better output stability
- Excellent beam quality
- No need for tight coiling
- No coiling-induced mode area compression
See also our white paper on DC-200/40-PZ-Yb modal properties
The output of the ytterbium-doped DC-200/40-PZ-Yb fiber from NKT Photonics where the 1064 nm seed laser (~6 µm spot size) launch position is scanned across the input facet of the fiber. Only the fundamental mode (LP01) is present in the output beam. When the input launch position is changed the mode profile is maintained but with reduced power. This demonstrates the single-mode property of the DC-200/40-PZ-Yb.
