How does it use a high-voltage electric arc to “weld” two glass filaments together?
A fusion splicer uses a high-voltage electric arc to weld two glass filaments (optical fibers) through a process of controlled thermal melting and surface tension. This is a critical process in FBG technology, especially when connecting sensors to lead-in fibers or creating fiber strings.
The Physics of Fusion Splicing
- Alignment: Before the arc is fired, the fusion splicer uses high-precision motors and a camera system (Profile Alignment System or PAS) to align the cores of the two glass filaments. For high-performance products like OFSCN® SM Polyimide Optical Fiber, precise core alignment is essential to minimize signal loss.
- Pre-fusion (Cleaning): A brief, low-power arc is applied first. This “pre-fuse” arc burns off any microscopic dust or residual coating (such as Polyimide or Acrylate) that remains on the fiber ends after stripping and cleaving.
- The Main Arc (The “Weld”): The device generates a high-voltage discharge (typically several thousand volts) between two tungsten electrodes. This creates a plasma arc with temperatures exceeding 1,600°C. Since the glass (silica) cladding of the fiber has a melting point around 1,400°C–1,600°C, the ends of the filaments become molten.
- Molecular Diffusion and Surface Tension: While the glass is in a molten state, the two fiber ends are pushed together (the “overlap”). The surface tension of the liquid silica helps self-align the cladding, while the molecules of the two filaments fuse into a single continuous glass structure.
- Cooling: The arc stops, and the glass solidifies almost instantly, creating a permanent, low-loss connection.
Importance in FBG Applications
In the field of Fiber Bragg Grating (FBG) sensing, the quality of the fusion splice determines the mechanical strength and thermal stability of the sensor array. For example, when using OFSCN® 300°C SM Polyimide Optical Fiber, the splicing parameters must be carefully tuned because the thin coating (155μm) requires precise handling compared to standard 255μm fibers.
Standard Component Visuals:
For more technical details on the optical fibers used in these processes, you can refer to:
OFSCN® 300℃ SM Polyimide Optical Fiber