Photodynamic therapy (PDT) is a novel promising method to treat cancer. As the name implies, it requires that optical power is delivered with surgical precision to the disease-affected regions. Optical power density, its uniformity and emission angle play a critical role in the PDT therapy, hence special fiber-based light diffusers have to be used in the method to deliver the light. Whereas standard fibers emit light from their end, light diffusers are engineered so that light is emitted from the cladding around its full perimeter and over a predefined length (and in most cases it is advantageous that as little initial power reaches the far end of the fiber as possible). Fibrain have developed a novel approach to manufacture fiber-based light diffusers, which allows to fabricate them on almost all types of optical fiber and with a controlled length of the light-emitting region. Now, after the legal process is complete, our innovative technology is officially patent protected!