Abstract: In general, in one aspect, the disclosure features a system that includes a flexible waveguide having a hollow core extending along a waveguide axis and a region surrounding the core, the region being configured to guide radiation from the CO2 laser along the waveguide axis from an input end to an output end of the waveguide. The system also includes a handpiece attached to the waveguide, wherein the handpiece allows an operator to control the orientation of the output end to direct the radiation to a target location of a patient and the handpiece includes a tip extending past the output end that provides a minimum standoff distance between the output end and the target location.

Abstract: In general, in one aspect, the disclosure features a system that includes a flexible waveguide having a hollow core extending along a waveguide axis and a region surrounding the core, the region being configured to guide radiation from the CO2 laser along the waveguide axis from an input end to an output end of the waveguide. The system also includes a handpiece attached to the waveguide, wherein the handpiece allows an operator to control the orientation of the output end to direct the radiation to a target location of a patient and the handpiece includes a tip extending past the output end that provides a minimum standoff distance between the output end and the target location.

Abstract: In general, in one aspect, the disclosure features a system that includes a flexible waveguide having a hollow core extending along a waveguide axis and a region surrounding the core, the region being configured to guide radiation from the CO2 laser along the waveguide axis from an input end to an output end of the waveguide. The system also includes a handpiece attached to the waveguide, wherein the handpiece allows an operator to control the orientation of the output end to direct the radiation to a target location of a patient and the handpiece includes a tip extending past the output end that provides a minimum standoff distance between the output end and the target location.

Abstract: In general, in one aspect, the disclosure features a system that includes a flexible waveguide having a hollow core extending along a waveguide axis and a region surrounding the core, the region being configured to guide radiation from the CO2 laser along the waveguide axis from an input end to an output end of the waveguide. The system also includes a handpiece attached to the waveguide, wherein the handpiece allows an operator to control the orientation of the output end to direct the radiation to a target location of a patient and the handpiece includes a tip extending past the output end that provides a minimum standoff distance between the output end and the target location.

Abstract: In general, in one aspect, the disclosure features a system that includes a flexible waveguide having a hollow core extending along a waveguide axis and a region surrounding the core, the region being configured to guide radiation from the CO2 laser along the waveguide axis from an input end to an output end of the waveguide. The system also includes a handpiece attached to the waveguide, wherein the handpiece allows an operator to control the orientation of the output end to direct the radiation to a target location of a patient and the handpiece includes a tip extending past the output end that provides a minimum standoff distance between the output end and the target location.

Abstract: In general, in one aspect, the disclosure features a system that includes a flexible waveguide having a hollow core extending along a waveguide axis and a region surrounding the core, the region being configured to, guide radiation from the CO2 laser along the waveguide axis from an input end to an output end of the waveguide. The system also includes a handpiece attached to the waveguide, wherein the handpiece allows an operator to control the orientation of the output end to direct the radiation to a target location of a patient and the handpiece includes a tip extending past the output end that provides a minimum standoff distance between the output end and the target location.

Abstract: In general, in one aspect, the disclosure features a system that includes a flexible waveguide having a hollow core extending along a waveguide axis and a region surrounding the core, the region being configured to, guide radiation from the CO2 laser along the waveguide axis from an input end to an output end of the waveguide. The system also includes a handpiece attached to the waveguide, wherein the handpiece allows an operator to control the orientation of the output end to direct the radiation to a target location of a patient and the handpiece includes a tip extending past the output end that provides a minimum standoff distance between the output end and the target location.

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: 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 a waveguide that includes a core extending along a waveguide axis and a confinement region surrounding the core. The confinement region includes a spiral portion and a non-spiral portion, wherein the spiral portion and the non-spiral portion extend along the waveguide axis.

Abstract: In general, in one aspect, the invention features methods that include guiding radiation at a first wavelength, ?1, through a core of a photonic crystal fiber and guiding radiation at a second wavelength, ?2, through the photonic crystal fiber, wherein |?1??2|>100 nm.

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, ?, 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=?/(4?{square root over (n12?1)}) and d2QW=?/(4?{square root over (n22?1)}), respectively.

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 systems, including a photonic crystal fiber including a core extending along a waveguide axis and a dielectric confinement region surrounding the core, the dielectric confinement region being configured to guide radiation along the waveguide axis from an input end to an output end of the photonic crystal fiber. The systems also includes a handpiece attached to the photonic crystal fiber, wherein the handpiece allows an operator to control the orientation of the output end to direct the radiation to a target location of a patient.

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, ?, 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=?/(4{square root}{square root over (n12?1)}) and d2QW=?/(4{square root}{square root over (n22?1)}), respectively.

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 systems, including a photonic crystal fiber including a core extending along a waveguide axis and a dielectric confinement region surrounding the core, the dielectric confinement region being configured to guide radiation along the waveguide axis from an input end to an output end of the photonic crystal fiber. The systems also includes a handpiece attached to the photonic crystal fiber, wherein the handpiece allows an operator to control the orientation of the output end to direct the radiation to a target location of a 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: In general, in one aspect, the invention features a waveguide that includes a core extending along a waveguide axis and a confinement region surrounding the core. The confinement region includes a spiral portion and a non-spiral portion, wherein the spiral portion and the non-spiral portion extend along the waveguide axis.