상용 MMF를 사용한 O-band 및 C-band용 빔 확산형 광섬유 분석 및 제작 연구

Abstract

Optical communication lenses are efficient, but expensive and generating a lot of losses. To overcome this limitation of lenses, researches have been continuously fulfilled to use Graded-index Multi-mode fibers (GRIN-MMFs) with a high refractive index instead of other lenses but most of the efforts showed high insertion loss. In this paper, an efficient method to produce a low-loss beam expanded fiber is proposed using commercially available GRIN-MMFs and working simultaneously at the O-band and C-band. The core diameters of the GRIN-MMFs presented in this paper are 50 μm, 62.5 μm, 85 μm with the cladding diameter of 125 μm. by simulating the fused connection of Single-mode optical fiber (SMF) and GRIN-MMF, an optimum length LOP of the GRIN-MMF which shows adequate focusing behavior will be suggested and a low-loss beam expanded fiber also be manufactured based on the simulation. Using light source in the wavelength bands of 1310 nm and 1550 nm, optical loss in dB of the beam expanded fiber was measured at the working distances WD of 10 μm, 30 μm, 50 μm, and 100 μm. The measured loss for the beam expanded fibers with the core diameter of 50 μm at WD=100 μm was within 0.60 dB and 0.72 dB at the wavelengths of 1310 nm and 1550 nm, respectively. with the core diameter of 62.5 μm the loss was within 0.66 dB and 0.66 dB at 1310 nm and 1550 nm, respectively. Finally, with the core diameter of 85 μm the loss was under 0.80 dB and 0.61 dB at 1310 nm and 1550 nm, respectively. The results showed that it is Possible to produce all fiber type GRIN-fiber lenses with the advantages of low cost, high reliability, easy alignment and splicing, and resultingly easy produce.