A precision ground diamond blade is attached to a resonant acoustic stepped horn. The ultrasonic horn resonance is maintained by an electronic circuit for the duration of the cleave and then automatically terminated to preserve battery life. The ultrasonically vibrating blade moves slowly toward the tensioned fiber on stictionless damped bearings. Cleaving then takes place without the damage from compressive stresses and blade intrusion into the fiber that is typical of conventional cleavers. The adjustable diamond blade normally gives 20,000 cleaves and is replaceable. Select fiber cleavers according to your application requirements. Fiber cleavers, designed for fusion splicing, need a low average angle that is one degree or less, whereas cleavers appropriate for mechanical connectors require angles below three degrees. So determine whether you require a single-fiber or multi-fiber cleaver before you cleave the fibers at one time. A fiber cleaver utilizes an automatic anvil drop for fewer required steps and better cleaving consistency. The automated anvil design can save time and significantly improve the quality of the cleave by eliminating human error and subpar cleaves associated with scribes and manual cleavers. To perfectly cleave optical fibers, perform the following steps:

Fibers with particularly large diameters, e.g. beyond 200μm, can also be difficult to cleave. They need a higher tension force. By purchasing from reputable manufacturers, you’ll enjoy manufacturer support and warranties; service for periodic maintenance and cleaning that extends the life of the cleaver; and a cleaver made of the best durable metal materials. Note that it is often very worthwhile to carefully inspect fiber cleaves before using them, as later on it may be much more tedious to locate a fault. Even with a mechanical precision cleaver, the results may not be fully reliable because they require correct settings and can be spoiled by a defect blade, which is not easy to recognize. Additional Treatment: Polishing Cleaving is the process by which an optical fiber is “cut” or precisely broken for termination or splicing. Just like cutting glass plate, fiber is cut by scoring or scratching the surface and applying stress so the glass breaks in a smooth manner along the stress lines created by the scratch. Properly done, the fiber will cleave with a clean surface perpendicular to the length of the fiber, with no protruding glass on either end.There are laser-based devices (containing a CO 2 laser) which allow the preparation of fiber ends as an alternative to cleaving. Strictly speaking, the used process is not cleaving (which is a mechanical breaking process) but rather something like laser cutting. Nevertheless, it has become common to name it laser cleaving because it produces similar results. And an optical fiber cleaver is the tool to cut (called cleave in the fiber optic industry) the fiber in such a good way. In the cleaving process, the brittle glass fiber is fractured in a controlled manner as shown below.

Both optical fiber slicing techniques require that the fiber tips are a smooth end face that is perpendicular (90°) to the fiber axis as shown below. Cleaving is the standard method to obtain such surfaces, or sometimes the first step towards that goal. It is a process of controlled breaking of the glass of a bare fiber. It begins with making a tiny fracture (scratch) on the side of the fiber, e.g. with a sharp diamond, carbide or ceramic blade, before or while some defined tension or bending is applied to the fiber. This causes the fiber to break, starting at the mentioned fracture point: the fracture rapidly propagates over the full fiber cross-section. Often, the cleaving leads to a very clean surface of the obtained two fiber parts.

Problematic Cases

Since fracture is such a violent and difficult to control process, even the best commercial cleaver will sometime produce defective cleaves.

The optimum settings of a mechanical fiber cleaver – in particular, the applied tension – substantially depend on details like the glass materials and the fiber diameter. Often, fiber cleavers are pre-adjusted for silica fibers with the standard diameter of 125μm. For fluoride fibers or other mid-infrared fibers, for example, one may have difficulties finding suitable parameters for repeatable cleaving results. The quality of the obtained cleaves has different aspects, the relevance of which depends on the application:Sumitomo is most well known for their consistently high-quality fusion splicers which are now considered standard equipment by many technicians and engineers in the fiber optic field. Note that cleaving is not cutting, as the bulk of the process is just breaking. Only the initial tiny break is prepared with a blade. If fibers should be fusion-spliced, the cleaved surfaces should be quite precisely perpendicular to the axis and must be smooth over the whole fiber cross-section. For example, one could not properly but together the fiber surfaces if a fiber had a small protrusion (a part standing out), even if that is only near the edge, far away from the fiber core. Also, only for smooth regular surfaces, the surface tension of the softened fibers will optimally self-align the fibers during the fusion process. In addition, a kink shape due to non-perpendicular cleaves can cause substantial coupling losses, particularly for large mode area fibers. When we need to join two optical fibers together, we usually use mechanical splice or fusion splice. Tools for fiber cleaving are called fiber cleavers. Different kinds of such instruments are explained in the article on fiber cleavers. Simple and inexpensive cleavers, based e.g. on some pen-shaped scribes, are sufficient for simple purposes, when used with proper training. For a higher and more consistent cleave quality, which is less dependent on the operator, mechanical precision splicers are used, which are substantially more expensive. Problematic Cases

Conversely, if the Fresnel reflection of a fiber end needs to be exploited (e.g. for building a fiber laser), it is important to keep the cleave angle small – well below the beam divergence angle corresponding to the fiber mode. Large mode area fibers are more critical in this respect. AFL Telecommunications, a subsidiary of Fujikura Ltd. of Japan since 2005, is widely recognized by the telecommunications industry as one of the foremost fiber optic solution providers. A microscope may be required to properly inspect the obtained fiber surfaces. There are hand-held microscopes for such purposes, and fusion splicing apparatuses also often contain a microscope. Cleavers, like fusion splicers, continue to evolve with new and improved features, such as automated fiber scrap collection, automated scoring mechanisms, and the latest automatic blade rotation technology.

Also available on Newport.com

For very high-quality fiber surfaces, it is often necessary to apply some polishing procedure after cleaving. One may, for example, insert the fiber end into a hollow glass tube and fix it there with a glue. The tube gives the fiber a higher strength and is inserted into a polishing apparatus. The fiber is polished down together with the glass tube. This procedure allows one to produce a high-quality surface with an arbitrary well-defined orientation of the fiber surface. However, it takes substantially more time than simple cleaving. See the article on polishing of fibers for details. Laser Cleaving of Fibers