Using laser heating technology, the optical fiber can be stitching, which is more versatile than the traditional arc system. For decades, optical fiber splicing has depended on traditional heating methods, such as filament or electrode. Although laser heating is a known alternative method since 1970s, the commercially available carbon dioxide (CO2) laser source has recently attracted widespread interest in the industry.
CO2 laser processing has many obvious advantages. The laser source itself is very clean, which means that it does not bring any pollution to the final component, such as chemical electrode pollution, etc. At the same time, the laser can maintain a very stable state for a long period of time, thus reducing the maintenance demand.
However, compared with other electronic surface heating techniques, the main advantage is that the absorption heating is essentially different. By absorption, the heating process can directly point to where the process is crucial. The directional heating not only improves the quality of the available optical fiber components, but also realizes the unique shape and design of the fiber.
In order to make the absorption heating effective, the fiber forming tool is very important. With that in mind, Nyfors and Furlong Hoff Institute of Applied Optics and precision engineering developed a product called Smartsplicer, and fixed it on the ring beam, and processed it through the 360 degree angle of entry.
The annular design is made of patented Axicon splicing technology. The electric telescope in front can adjust the size and thickness of the ring, thereby improving the flexibility of the process. In addition, the incident angle of the laser beam can be dynamically changed in order to achieve the best heating performance. For example, the laser beam can be focused on the ring shape, used for the end cap splicing, or focused on the side of the optical fiber, for fiber to fiber splicing, cone-shaped or manufacturing optical fiber composite device (see Figure 1).
Figure 1. different configurations of laser beam (red) end cap splicing (a), coning and fiber splicing (b). (image source: Nyfors)
Structured optical fiber splicing
The advantages of Smartsplicer can be embodied by a variety of special applications. Nyfors has previously developed a new fiber optic sensor in collaboration with Swedish Institute, Serstech and Swedish police. In the project funded by VINNOVA, a Swedish government agency, the goal of the partners is to build an optical fiber sensor for detecting trace gases in crime or accident scene.
At present, the police dog is the most effective method to detect the above gas. However, the police dog does not specify the gas in the field, and it can not be available at any time. Through the sensor, police officers arriving at the scene can quickly determine whether there is an unstable gas in the air. The Raman spectrum of the gas is obtained by using an empty core fiber that can be quickly filled with the surrounding gas and emits light. However, in order to achieve this, the process of splicing hollow light into ordinary light is very important.
Figure 2. a typical fragile hollow core fiber for sensing applications.