Challenge
Laser Heated Pedestal Growth (LHPG) is a highly delicate fabrication technique for growing the highest quality crystals. This is accomplished by melting a narrow region with a highly controlled CO2 laser beam. The focused beam is moved along the crystal, or floating zone, and as the molten region melts the impure solid at its forward edge, it leaves a wake of purer material solidified behind it. However, for such a process to produce the highest quality of sapphire optical fibers, all parameters of this process must be actively monitored and controlled.
Solution
A unique light source is required to provide the high pulling rates of materials with very high melting points. The source must have unparalleled power stability to produce a uniform molten zone whose viscosity doesn’t negatively impact the drawing process. The Access Laser AL30-ST-FCCL provides the required functionality in a compact size allowing easy integration into the complex vacuum system, which holds the target crystal. Superior mode quality is also critical so the laser can to be properly guided by a reflaxicon, which radially distributes the laser energy over the molten zone, and reduces thermal gradients even further.
Results
The system’s ability to grow tapered fibers enables the fabrication of compact evanescent wave absorption sensors with exceptionally high sensitivity. Likewise, due to the sophistication and versatility of the system made possible by Access Laser technology, the monolithic all-crystalline ultra-probe, for the MicroMaterials OptoTemp 2000 fiber-optical thermometer, has the highest temperature measuring capability of any comparable device on the market.
