All-Fiber Gas Cell
A new type of optical fiber, known as photonic crystal fiber, allows for light to propagate over long distances with minimal losses through a hollow core that is only a few micrometers in diameter, formed in the center of a glass fiber. Such a fiber offers the potential of extremely strong interactions of light with gases in a highly compact geometry. However, until now it was not possible to create such an all-fiber gas cell in which the pressure could be varied. By using extremely short laser pulses to drill small holes through the side of the photonic crystal fiber to its core, such an all-fiber gas cell has been realized. Each end of the fiber is then spliced to a piece of conventional, all-glass fiber, sealing the fiber core, which can now be easily filled via the laser drilled holes with any gas. Light injected into the end of the fiber-cell system then passes through the fiber and interacts with the gas over distances that can extend many meters and yet the light remain tightly confined to the core. By injecting gases that respond very strongly to light, the result can be an optical device whose transmission properties are sensitive to light beams that contain only a few photons, a response which is necessary for quantum communication applications.
SEM image of a photonic-crystal fiber laser drilled with 80-nJ pulses and (b) close-up image of drilled capillary formed in the side of fiber, the diameter of the channel is 1.5 μm.
[Lead CNS Investigator: Gaeta group – Nanophotonics Thrust, Center for Nanoscale Systems]
For additional information see:
- C. J. Hensley, D. H. Broaddus, A. L. Gaeta, and C. B. Schaffer, “Photonic band-gap fiber gas cell fabricated using femtosecond micromachining,” subm. to Optics Express (2007).