Optical Fiber Evolver Code

Soldered Metallized Optical Fiber

Pretty Solder is used in some interconnects to hold optical fiber in alignment with optoelectronic devices, e.g. lasers or P-I-N junction sensors. (See, for example, this paper by Powell et al.) Typically, the fiber is fixed by "tweezers" some distance from the end of the fiber, and the solder placed next to the fiber between the tweezers and the device. The solder is then melted, and surface tension pulls it over the wetting pad and onto the fiber. The surface tension of the molten solder also pulls the fiber toward the substrate, resulting in a shift out of alignment with the device.

Pictures This evolver file is used to predict the shape of the solder droplet around the fiber, the capillary force exerted on the fiber, and the bending shift of the fiber due to that capillary force. In these pictures, the fiber is shown in its original unshifted position, and the holes show where Evolver predicts the fiber has shifted to when the solder reaches its equilibrium shape. The bounding box in the top picture is aligned with the fiber, showing the tilt of the fiber relative to the substrate.

To use this file, modify the paramters to meet your needs, press "Submit", and save the result as fiber.fe. Next, run "evolver fiber", and when you have an Evolver prompt, type evolve, and it will automatically run to completion, refining and smoothing the mesh as it goes.

Substrate wetting pad width (mm):
Substrate wetting pad length (mm):
Solder contact angle on pad (degrees):
Solder contact angle on fiber (degrees):
Total droplet volume (mm^3):
Fiber radius (mm):
Density (ignored):
Solder surface energy (g/s^2):
Initial "pitch" angle (radians):
Initial "yaw" angle (radians):
Original fiber center height (mm):
Original fiber y-offset (mm):
Length from fiber fixed end to droplet center (mm):
Length from droplet center to fiber free end (mm):
Fiber modulus, g/(mm-s^2):