Abstract:
In general, in one aspect, the invention features an apparatus that includes a photonic crystal fiber configured to guide a mode of electromagnetic radiation at a wavelength, λ, along a waveguide axis. The fiber includes a core extending along the waveguide axis, and a confinement region extending along the waveguide axis and surrounding the core. The confinement region includes alternating layers of a first and a second dielectric material having thicknesses d1 and d2 and different refractive indices n1 and n2, respectively. The thickness of at least one of the alternating layers of the first material_differs from thickness d1QW or at least one of the alternating layers of the second material_differs from thickness d2QW, where d1QW and d2QW correspond to a quarter-wave condition for the two dielectric materials given by d1QW=λ/(4{square root}{square root over (n12−1)}) and d2QW=λ/(4{square root}{square root over (n22−1)}), respectively. The photonic crystal fiber has an attenuation for the guided mode at the wavelength λ that is reduced by a factor of about two or more relative to an attenuation for a reference fiber that is identical to the photonic crystal fiber except that the reference fiber has alternating layer thicknesses corresponding to the quarter-wave condition.
Abstract:
In general, in one aspect, the invention features methods that include directing radiation to a target location of a patient through a photonic crystal fiber, the photonic crystal fiber having a hollow core and flowing a fluid through the hollow core to the target location of the patient.
Abstract:
In general, in one aspect, the invention features apparatus that include an assembly including a radiation input port configured to receive radiation from a radiation source and an output port configured to couple the radiation to a photonic crystal fiber, the assembly further including a retardation element positioned to modify a polarization state of the radiation received from the radiation source before it is coupled to the photonic crystal fiber.
Abstract:
Apparatus for supporting fabric such as a net curtain 5 over an aperture such as a window comprises first and second members 4 and 2 respectively which have exposed faces which are mutually magnetically attractive, the sacond member 2 being L-shaped to provide below its exposed face a ledge for supporting the first member 4.