Process development for Cross Mode Coupling of Optical Fibers

In this SBIR program, Q-Peak will develop a continuous manufacturing process to facilitate deterministic cross coupling between optical fibers.  The process will allow managing mode coupling in two-fiber sensor architectures, coupling of power from pump fibers to gain fibers for fiber lasers in a distributed length methodology and formation of unique signal add/drop functionality for optical networks.  Q-Peak will focus on the process development of a side-pumping architecture for fiber lasers as this allows managing the amount of energy coupled per unit length between pump fibers and the gain fiber.  The primary advantage for fiber lasers is that length management of pump coupling is, to first order, equivalent to managing thermal rise in the gain fiber avoiding thermal runaway and destructive effects of over pumping based on specific dopant ions and dopant density in the active fiber. We will address the manufacturability, electrical-to-optical and optical-to-optical efficiency, and a risk assessment of other parameters important to the energy transfer process. While side-pumping has been demonstrated for Ytterbium-doped fiber lasers, the diversity of ions used in fiber lasers (Yb, Nd, Yb-Er, Er, Tm, and Pr) requires a flexible and adaptable coupling process where the energy transfer can be tailored to the specific fiber construction, mode space, materials, and the specific dopant ion density.