We demonstrate a simple method for efficient coupling of standard single-mode optical fibers to a high- Q optical microsphere cavity. Phase-matched excitation of whispering-gallery modes is provided by an angle-polished fiber tip in which the core-guided wave undergoes total internal reflection. In the experimental setup, which included a microsphere with both an input and an output coupler, the total fiber-to-fiber transmission at resonance reached 23% (total insertion loss, 6.3 dB), with loaded quality factor <i>Q</i>≥3×10<sup>7</sup> and unloaded <i>Q</i>≈1.2×10<sup>8</sup> at 1550 nm. A simple pigtailing method for microspheres permits their wider use in fiber optics and photonics devices.
© 1999 Optical Society of America
(060.0060) Fiber optics and optical communications : Fiber optics and optical communications
(130.1750) Integrated optics : Components
(230.0250) Optical devices : Optoelectronics
(270.0270) Quantum optics : Quantum optics
Vladimir S. Ilchenko, X. Steve Yao, and Lute Maleki, "Pigtailing the high-Q microsphere cavity: a simple fiber coupler for optical whispering-gallery modes," Opt. Lett. 24, 723-725 (1999)