Optical fiber diffuser

摘要

Optical fiber diffusers for emitting light cylindrically along a length of the fiber diffuser with preselected light intensity distributions along the length of the diffuser. The diffuser portion is defined by forming a Bragg grating in a section of the optical fiber core having a modulated index of refraction which acts to couple light radially out of the fiber along the diffuser section. The intensity distribution of light coupled out of the diffuser section of the fiber is controlled by controlling the profile of the modulated index of refraction, namely the coupling coefficient, along the length of the grating. For photodynamic therapy type II strong Bragg gratings are preferred which give higher intensity output over short distances. Multiple Bragg gratings can be written into a multimode fiber for emission of light at several positions along the fiber. Writing a Bragg grating into a multimode fiber provides a method of monitoring transmission in the fiber since some of the light can be coupled out and detected and interrogated. The diffuser device can be used as sensors since they also couple light incident on the diffuser into the core where it is transmitted to a detector.