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: Apparatus is provided for reducing hypertension of a subject. A selective circumferential pressure applicator (60) includes at least two surfaces (61) that increase baroreceptor activity of the subject, by applying pressure to an artery (20) of the subject at two or more respective non-contiguous regions around the circumference of the artery, at a longitudinal site of the artery, such that between the non-contiguous regions, at the longitudinal site (a) there is at least one region (22) of the artery that is more relaxed than in the absence of the device, and (b) there is at least one region (21) of the artery that is more tense than in the absence of the device. A joint (63) couples the surfaces to each other. For at least a portion of the subject's cardiac cycle, the joint does not to contact the subject's artery. Other applications are also provided.

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: Apparatus and methods are described including an implantable device shaped to define (a) at least two artery-contact regions, the artery-contact regions comprising struts that are configured to stretch an arterial wall by applying pressure to the arterial wall, and (b) at least two crimping regions that comprise locking mechanisms configured to prevent the crimping regions from becoming crimped due to pressure from the wall of the artery on the artery-contact regions. The crimping regions are configured to be crimped during insertion of the device, via a catheter, by the locking mechanisms being unlocked during insertion of the device. Other embodiments are also described.

Abstract: Apparatus and methods are described, including identifying a subject as suffering from hypertension. In response to the identifying (a) a radius of curvature of a first set of at least three regions of an arterial wall of the subject is increased at a given longitudinal location, while (b) allowing the first set of regions of the arterial wall to pulsate. A device is implanted inside the artery at the longitudinal location such that the device applies pressure to the arterial wall at a second set of at least three regions of the artery, but does not contact the first set of regions, the first set of regions and the second set of regions alternating with each other. Other embodiments are also described.

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 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: An optical waveguide including: a dielectric core region extending along a waveguide axis; and a dielectric confinement region surrounding the core about the waveguide axis, the confinement region comprising a photonic crystal structure having a photonic band gap, wherein during operation the confinement region guides EM radiation in at least a first range of frequencies to propagate along the waveguide axis, wherein the core has an average refractive index smaller than about 1.3 for a frequency in the first range of frequencies, and wherein the core a diameter in a range between about 4? and 80?, wherein ? is a wavelength corresponding to a central frequency in the first frequency range.

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 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 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: High index-contrast fiber waveguides, materials for forming high index-contrast fiber waveguides, and applications of high index-contrast fiber waveguides are disclosed.

Abstract: An optical waveguide having a working mode with a tailored dispersion profile, the waveguide including: (i) a dielectric confinement region surrounding a waveguide axis, the confinement region comprising a photonic crystal having at least one photonic bandgap, wherein during operation the confinement region guides EM radiation in a first range of frequencies to propagate along the waveguide axis; (ii) a dielectric core region extending along the waveguide axis and surrounded by the confinement region about the waveguide axis, wherein the core supports at least one guided mode in the first frequency range; and (iii) a dielectric dispersion tailoring region surrounded by the confinement region about the waveguide axis, wherein the dispersion tailoring region introduces one or more additional modes in the first range of frequencies that interact with the guided mode to produce the working mode.