Flat Ridge Fiber for Fundamental Model Power Scaling From Single Aperture
Final rept. 15 Feb-29 Oct 2007
LIEKKI OY LOHJA (FINLAND)
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This report results from a contract tasking Liekki Oy as follows i. Design, Growth and Fabrication of Preforms. At least 3-4 preforms with 2 or more different core dimensions and refractive indices will be produced. Early design and simulation work will be carried out to provide several iterations of target cross sections for the composite ridge fiber. Preliminary evaluations indicated that the area of the Yb doped core can be 2-4 times greater in a rib waveguide than in a standard step index fiber while still delivering single mode. The planar glass structure provides a great deal of flexibility in selecting the relative dimensions of the active core, the undoped slab and surrounding cladding. In addition to preform growth, the applicability of existing bonding and grinding technologies to flat ridge structures will be evaluated . Bonding techniques for different glass structures utilized to attach the different parts of the flat ridge fiber perform are especially challenging because of potential impact of interface quality on the final mode shape. Similarly, grinding tolerances may be more stringent these will have to be carefully evaluated. Ridge Fiber Drawing Technology elements for drawing rectangular fibers were successfully developed at Liekki in the past year, but implemented in practice only for clad passive fibers used to deliver diode radiation. The application of the drawing technologies to the case of active ridge fibers is especially challenging because the fibers cannot cannot spin during the process. On this objective we will address key fiber drawing challenges sleeving and drawing speed Preliminary lasing experiments of selected prototype flat ridge fiber. These will be constructed as feasibility demonstrations designed to provide proof-of-concept validations of the basic ridge fiber approach. The experiments will be conducted at Liekki, using in-house diodes, splicing equipment, optics and test equipment.
- Lasers and Masers
- Fiber Optics and Integrated Optics