Efficient power coupling from a 980-nm, broad-area laser to a single-mode fiber using a wedge-shaped fiber endface

• Published in: Journal of lightwave technology Vol. 8; no. 9; pp. 1313 - 1318
• Main Authors: Shah, V.S., Curtis, L., Vodhanel, R.S., Bour, D.P., Young, W.C.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: New York, NY IEEE 01-09-1990; Institute of Electrical and Electronics Engineers
• Subjects: Applied sciences; Circuit properties; Diode lasers; Electric, optical and optoelectronic circuits; Electronics; Erbium-doped fiber lasers; Exact sciences and technology; Fiber lasers; Integrated optics. Optical fibers and wave guides; Laser beams; Laser excitation; Laser theory; Optical and optoelectronic circuits; Optical coupling; Optical fiber polarization; Power lasers; Pump lasers; Geometrical configuration; Single mode waveguide; Optical coupling; Laser; Optical circuit; Optical fiber
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/50.59158

A theoretical and experimental study of an efficient technique for coupling a broad-area laser to a single-mode fiber without the use of bulk optical components was carried out. The technique uses a wedge-shaped fiber endface to approximate a cylindrical lens action to correct for the phase mismatch between the curved laser beam wavefront and the planar fiber beam. A theoretical formula for the coupling efficiency in the absence of both angular and transverse misalignments is derived. By optimizing the wedge angle and the axial separation between the laser facet and the fiber endface, a maximum coupling efficiency of 47%, compared to 20% for the square endface, achieved, resulting in 15.2 mW of power in the single-mode fiber. The fabrication process consists of a simple polishing procedure requiring a wedge-shaped polishing tool and is highly reproducible.< >