The Pump and PM signal combiner is vital for high-power fiber lasers and amplifiers, efficiently merging multiple pump lasers with a polarization-maintaining signal into a single output fiber. Pump and PM Signal Combiner perform a very important task however, their development is not without major technical challenges.

So, let us look at some common development challenges in the creation of Pump and PM signal combiners.

Common Issues During Production of Pump and PM Combiners

Mode Field Matching

The major difficulty in designing a Pump and PM signal combiner is successfully matching the mode field and mode field diameters of the input fibers and output fibers. The larger the mode field mismatch, the higher the insertion might be experienced and, hence, poorer power transfer.

Even worse, if the signal is also in the polarization maintaining system, complications arise likely resulting in higher losses. Designers need to match core diameters, numerical aperture, and refractive index profiles to ensure losses are kept to a minimum while maintaining signal integrity.

Polarization Alignment and Adjustment

The polarization of the signal channel is a basic requirement to be maintained by a PM combiner. Even a small misalignment results in polarization crosstalk that compromises system performance. It is important to have precise rotational alignment between PM fibers during manufacturing to ensure that the slow and fast axes are properly aligned.

Thermal and mechanical stress could also cause birefringence variation during operations and this hampers the challenge of achieving long-term polarization stability.

Thermal Management at High Optical Power

The importance of thermal management increases when optical power increases. A Pump and PM signal combiner with a couple watts of optical power to a kilowatt must dissipate excess heat readily. Poor thermal design may lead to fiber breakdown, coating deterioration, or mode instability.

Material selection, packaging design, and possibly active cooling are all important elements to combat thermal accumulation particularly for small footprint combiners.

Complexity of Splicing and Assembly

When assembling a Pump and PM signal combiner, the complexity of precise and intricate manipulation of different fibers requires fusion splicing where all splices must be optimized to achieve strength and stability with good optical performance under thermal cycling.

The complexity of designing Pump and PM signal combiners is further increased by the additional level of precision needed with polarization maintaining fibers. Within a typical assembly of this type, active alignment has to be done during splicing to stabilize polarization extinction ratios in the combined polarization state.

Back Reflection and Optical Isolation

Design complexity also arises from the concerns regarding back reflections, especially in high power systems.  To avoid negative feedback due to return loss that may destabilize laser sources or damage components, a Pump and PM signal combiner design requires the need to minimize return loss within the combined system.

Return loss qualities in our combiner can be made better or worse through anti-reflective coatings, angled splicing, mode-field control, etc.  In addition to the above concerns, designing optical isolation and low insertion loss adds additional complexity to the overall design.

So, if you are looking for reliable Pump and PM signal combiners, visit DK Photonics online today.