Erbium-Ytterbium Doped Fibers For Cladding Pumped Amplifiers

Fibercore’s range of Erbium-Ytterbium (ErYb) doped fibers are deployed globally in LiDAR, laser and amplifier applications. They may be found in automotive ADAS units, civilian and military LiDAR ranging systems, satellite to satellite communications systems, high powered telecoms optical amplifiers and as seed lasers or amplifiers in fiber lasers. These applications present a diverse range of requirements on the fiber, subsequently Fibercore have developed three families of ErYb doped fibers to address these needs: Cladding Pumped (CP), Triple Clad (TC) and Double Clad (DC) fibers.

 

The all-silica design of the CP and SMM (Single Mode and Multi Mode) fibers ensures that all pump light is guided within the silica structure, without any pump light reaching the coating. This design removes the risk of the fiber losing pump guidance due to coating damage or coating degradation, making the CP and SMM fibers ideal for high volume manufacturing lines and harsh environments as found in automotive, military and space applications. Subsequently, different coating types may be used depending on the application environment, for example a high temperature acrylate coating can be used for applications of up to 150°C. As the pump guidance comes from the silica structure, allowing a pump NA of around 0.22, these fibers are optimized for single pump systems or side coupled pumping.

• Multiple Mode Field Diameter (MFD) options
• Premuim product where the pump guidance is confined to the “all-silica” boundary of the inner cladding (either octagonal or petal shaped, nominally ~105 μm Ø).

These fibers are designed for use with 0.22 NA pump fibers, where the pump is fully confined to 105 μm inner cladding. Matched with passive fibres SMM900, SMM1500 and MM(105/125)0.22 to maximise performance, while simplifying procurement.

Circular outer cladding gives lower average splice loss and higher repeatability than octagonal cladding structures

For applications that require use of higher NA (≥0.45) pump guides, we recommend our suite of HD low index coated Er-Yb doped fibers, e.g., TC1500Y(11/125)HD, and matched passive fiber range, e.g. DC1500(11/125)0.12HD.

• The fiber can be stripped, cleaved, spliced, and recoated as if it was standard Single Mode Fiber (SMF) as there is no low index coating
• Circular outer cladding gives lower average splice loss and higher repeatability than octagonal cladding structures

For applications that require use of higher NA (≥0.45) pump guides, we recommend our suite of HD low index coated Er-Yb doped fibers, e.g., TC1500Y(11/125)HD, and matched passive fiber range, e.g. DC1500(11/125)0.12HD.

ADVANTAGES

• Ideal for low-cost manufacturing lines as the fiber can “piggyback off” Erbium-Doped Fiber Amplifier (EDFA) production lines
• CP fiber can be striped, cleaved and spliced just like a standard telecoms fiber
• Standard splice protectors can be used (does not need low index recoat)
• Round cladding is easier to splice with exceptional reliability
• Performance independent of coating quality.

Triple clad (TC) fibers offer the ultimate performance for high power reliability and splice repeatability, making them ideal for high performance, high reliability amplifiers and lasers. The inner octagon ensures most of the pump modes are confined away from the glass coating interface, limiting the pump energy level reaching the coating and reducing the probability of failure in case of any coating damage. The circular outer cladding ensures high quality cleaving and accurate core alignment is possible for highly repeatable low splice loss. As the coating assists with guiding the pump modes, high NA pump combiners with around 0.45 NA can be used for the highest pump power input.

• Core Mode Field Diameter options of 6 μm and 11 μm
• Premium product offering the “best of both worlds” geometry, containing a 0.45 NA Outer pump guide – Circular outer cladding, pump confined by the glass/low index polymer boundary (125 μm Ø).

Available with matched passives for use with 0.45 NA pump fibers and pump combiners, e.g., DC1500(11/125)0.12HD, where the pump fills the full 125 μm cladding.

• Fibercore’s novel “High Durability” HD low index coating package, provides world leading power handling, reliability and environmental resistance in a 0.45 NA fiber.
• TC geometry enhances pump mode mixing and results in outstanding fiber efficiency.
• Circular outer cladding means that the fiber can be easily stripped, cleaved and spliced, and maximises mechanical reliability.
• Talk to us about your splice and recoat needs, as we have multiple approaches for different system requirements.

ADVANTAGES

• Reduces pump energy at the glass-coating interface
• Increases absorption
• Improves reliability
• Compatible with standard fiber laser pump combiners
• Round cladding is easier to splice

For high volume, low bill of material (BoM), cost sensitive designs where a trade off in robustness and performance against price is acceptable, the Double Clad (DC) range of fibers offer an excellent option. The DC fibers have the same high-quality core composition of the CP and TC fibers but differ in the pump guide where the DC active fiber has an octagonal cladding with a 0.45 NA low index coating. This cladding and coating structure is a standard in the laser industry and performs exceptionally well in production lines that take care with handling the coating and have designs which can tolerate marginally higher splice losses. 

• Core Mode Field Diameter options of 6 μm and 11 μm
• Cost effective product containing a single 0.45 NA pump guide with octagonal outer cladding, pump confined by the glass/low index polymer boundary (nominally ~125 μm Ø)

Suitable for use with 0.45 NA double clad fibers and pump combiners, e.g., DC1500(11/125)0.12HD, where the pump fills the full 125 μm cladding.

• Fibercore’s HD (High Durability) low index coating package, provides world leading power handling and reliability in 0.45 NA fibers.
• Octagonal outer for cost sensitive applications

• Lower cost option to more premium fibers
• Compatible with standard fiber laser pump combiners

At Fibercore, we are always innovating and improving our fiber designs to enable new products or improve existing ones and we welcome feedback for future fiber designs. If your business has specific needs for a certain application, get in touch with our team on sales@fibercore.com.