Fabrication of 4 × 1 signal combiner for high-power lasers using hydrofluoric acid

• Published in: Optics express Vol. 26; no. 23; pp. 30667 - 30677
• Main Authors: Choi, In Seok, Park, Jongseon, Jeong, Hoon, Kim, Ji Won, Jeon, Min Yong, Seo, Hong-Seok
• Format: Journal Article
• Language: English
• Published: United States 12.11.2018
• ISSN: 1094-4087; 1094-4087
• DOI: 10.1364/OE.26.030667

We report a new method to fabricate a 4 × 1 signal combiner that comprises an output fiber port and a tapered fused bundle (TFB) with four input fiber ports. The TFB is etched in a solution of hydrofluoric acid and spliced with an output fiber of core diameter 105 μm and cladding diameter 125 μm. Each cladding of the four input optical fiber is etched to approximately 72.5 μm. The etched TFB was fabricated by tapering after forming a bundle of four etched optical fibers. Subsequently, the 4 × 1 signal combiner is fabricated by fusion splicing between the fabricated TFB and output optical fiber with a numerical aperture of 0.15. The efficiency of each port of the fabricated 4 × 1 signal combiner is in the range of 93.3-98.3%. When an optical power of approximately 624.5 W was input to the signal combiner, the maximum output was ~612 W and the efficiency was ~98%. The beam quality factor, M 2is measured to be approximately 14.6, which is calculated as the beam parameter product (BPP) of 5.02 mm·mrad.