Optical fibers with selected claddings (e.g., micro-structured claddings) are well known, for example from U.S. Pat. Nos. 5,907,652, 6,522,820, 6,594,429, 6,766,088 and 6,775,450. In the fibers described in one or more of these patents an apparent aim is to introduce some regions of air or other selected refractive index into the involved cladding to give it a different (e.g., lower) effective index than would otherwise be the case and thereby give the fiber characteristics, such as increased power handling ability, attractive for some applications.
In the known fibers having selected cladding designs, such as, for example, micro-structured claddings, the formation of the micro-structure can be an expensive and/or difficult matter, and usually is achieved by the making of holes in the cladding material of a preform from which the fiber is drawn, and these holes become extended over great lengths in the drawing of the fiber from the preform.
Although one or more of the known optical fibers may have had certain features that represented or were thought to represent an advance in the art when introduced, disadvantages or drawbacks remain, particularly with regard to certain applications.
Accordingly, it is an object of the present invention to provide an improved optical fiber that can address one or more of the disadvantages or drawbacks of the prior art.
Other objects and advantages of the invention will be apparent from the following description of preferred embodiments.