By using the diffracted field of the LP<sub>11</sub> mode of a hollow-core optical fiber, we have produced a micrometer-sized, focused dark laser spot in the near field of the fiber. The minimum half-width of the dark spot is less than 1 <i>μ</i>m . In particular, by masking the hollow core and metal coating the cladding with a microsphere, we blocked the light propagating in the cladding and obtained a clean dark spot, which may be useful in atom-optical experiments such as with atomic lenses, atom traps, and atom switches.
© 2001 Optical Society of America
(000.4930) General : Other topics of general interest
(020.7010) Atomic and molecular physics : Laser trapping
(050.1940) Diffraction and gratings : Diffraction
(140.3300) Lasers and laser optics : Laser beam shaping
Yong-Il Shin, Kihwan Kim, Jong-An Kim, Heung-Ryoul Noh, Wonho Jhe, Kyunghwan Oh, and Un-Chul Paek, "Diffraction-limited dark laser spot produced by a hollow optical fiber," Opt. Lett. 26, 119-121 (2001)