Extending single mode performance of all-solid large-mode-area single trench fiber

Abstract

Abstract:We report a novel "single trench fiber" design for mode area scaling of the fundamental mode while offering effective single mode operation for a compact fiber laser device. This fiber design allows very high suppression of the higher order modes by offering high loss and power delocalization. It has the advantages of low cost and easy fabrication thanks to all solid fiber design, cylindrical symmetry, and higher refractive index of core as that of the cladding. A Yb-doped single trench fiber with a 40µm core diameter has been fabricated from modified chemical vapor deposition process in conjunction with solution-doping offering an effective mode area of as large as ~1,000µm 2 at 1060nm for the bend radius of 20cm. Detailed characterizations confirm a robust single mode behavior of the fiber. Comparative analysis with other fiber designs shows significant performance enhancement of effective single mode operation suitable for fiber laser applications.

Highly efficient Yb-free Er-La-Al doped ultra-low NA large mode area single-trench fiber laser

“…A preform was fabricated using MCVD process in conjunction with solution doping process. We have used the similar recipe to fabricate this preform as that used for Yb-doped STF [12,13]. A flat refractive index profile was obtained as shown in Fig.…”

Trench-Assisted All-Solid Large-Mode-Area Fiber for Robust Single-Mode Operation

“…In order to address these issues, we have recently proposed all-solid single trench fiber (STF) having cylindrical symmetry and higher refractive index of core as of cladding for bend configuration that is needed for a compact laser device [3][4][5]. Our optimized modified chemical vapour deposition (MCVD) process in conjunction with solution doping technique has shown the suitability of STF design for mass-scale production.…”

“…On the other hand, the FM loss remains lower than 0.1dB/m and high power fraction in core (>80%). The detail of numerical analysis is reported in [5]. The STF is an all-solid structure and refractive index of core is higher than of cladding as shown in Fig.…”

“…1(a). Due to these two features, it has been fabricated by conventional MCVD process in conjunction with rod-in-tube process as reported in our previous studies [3][4][5]. We have fabricated three Yb-doped STFs having different core diameters of 20μm, 30μm, and 40μm.…”

“…Characterizations for these fibers ensure a Gaussian output. The details of experimental studies can be found in our publications [3][4][5]. For example, Fig.…”