An Optimized Vapor Phase Doping Process to Fabricate Large Core Yb-Doped Fibers

Abstract

The paper demonstrates a standardized process of vapor phase doping to fabricate large core Yb-doped preforms with longer useful length in reproducible manner. The optimization of the process led to successful achievement of Yb-doped core thickness of 4.5 mm (in 14.8 mm of preform diameter) by depositing up to 30 number of core layers with controlled amount of generated precursor vapors. The influence of the process parameters was studied rigorously to enhance the useful preform length up to 380 mm. A combination of Yb and Al in different proportions was doped into the core with uniform dopant concentration along the length by adjusting few process parameters efficiently. The Al 2 O 3 concentration up to the level of 17.8 mol% has been achieved successfully which resulted in NA of 0.31. This is the highest ever doping of Al in passive fibers by any modified chemical vapor deposition process. The Yb 2 O 3 content in the active fibers is as high as 0.47 mol%.

Synthesis and characterization of rare earth‐doped silica nanoparticles for optimizing vapor phase doping technique

“…In order to study the particle morphology, Al/Yb-doped soot particles were deposited inside a Heraeus F-300 silica tube (length 300 mm and diameter 20/17 mm) following VPD technique [can be found in details in our earlier publication ref 9 ]. The experiments were carried out at three vapor phase compositions of (i) pure SiO 3 [thd = 2,2,6, 6-tetramethyl-3,5-heptanedionate] were used as precursor materials for Al 2 O 3 and Yb 2 O 3 , respectively.…”

“…In this context, conventional solution doping (SD) method depicted several limitations specifically to make large core preforms with homogeneous dopant distribution along the preform length and resulted inadequate process reproducibility . The search for an alternate process led to the development of vapor phase doping (VPD) technique, which demonstrated high reproducibility for producing large core fibers in recent times …”

“…6 The search for an alternate process led to the development of vapor phase doping (VPD) technique 7 , which demonstrated high reproducibility for producing large core fibers in recent times. 8,9 While selection of the process technology plays an important role in getting the right kind of fiber, another major issue is to get control over RE and co-dopant incorporation level and their homogeneous distribution into silica network. In this regard, the role of deposition temperature and gas phase composition on pore size distribution is well known for SD method, which results in localized variation of Al/RE-salt during solution soaking step.…”

Vapor phase doping process for fabrication of rare earth doped optical fibers: Current status and future opportunities

“…By controlling these parameters judicially, the process reproducibility and dopants uniformity along the preform length could be increased substantially. It also has been reported that incorporation efficiency of Al in silica matrix is much higher than that of Yb .…”

Graded‐Index Ytterbium‐Doped Optical Fiber Fabricated through Vapor Phase Chelate Delivery Technique

“…[2][3][4] These techniques have been quite successful in embedding RE ions in multitude of optical waveguide structures, such as step, trench, and pedestal refractive-index profiles for specific applications. [5][6][7] Recent developments in spatial division multiplexing (SDM) and multimodal nonlinear pulse propagation have generated renewed interest in optical fibers with graded refractive-index (GRIN) profiles. [8,9] From transmission of information at high spectral efficiency to generation of visible supercontinuum, the multimode passive GRIN fibers are penetrating both in commercial and research space.…”