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345 Senior Design Project. Lasing Rare-earth doped microspheres. Lawrence Tai. Introduction. Under the direction of Professor Gary Eden, and those in the Laboratory of Optical Physics and Engineering, I attempted to create my own microspheres and to get them to lase. Goals. Etch fiber
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345 Senior Design Project Lasing Rare-earth doped microspheres Lawrence Tai
Introduction • Under the direction of Professor Gary Eden, and those in the Laboratory of Optical Physics and Engineering, I attempted to create my own microspheres and to get them to lase
Goals • Etch fiber • Create microsphere • Pump sphere in attempt to get it to lase • Test array of microspheres
Background - Fiber • ZBLAN Fiber (Zirconium, Barium, Lanthanum, Aluminum, and Sodium) • Transmits better than Silica glass, and wider spectrum • Fiber consists of coating, 125 μm cladding, and ~2 μm core.
Background - Microspheres • Good resonators with low losses • High Q (quality) value • Possibly uses in many different devices • Optical communication devices • Lasers • High resolution spectroscopy
Review of original design • Hydrogen Torch • Dye Laser • Lens • Fiber Holder
Etching process • Tetrahydrofuran (THF) – Remove Coating • Solution of 0.3M HCl and small amounts of Boric acid – etch cladding • Use DI water and Isopropynal to clean and dry fiber • Also tested solutions such as HF, H2SO4, and another solution with HCl and ZrOCl2
Microsphere creation • Used Hydrogen torch to create the microspheres
Microspheres • Holmium (Ho) doped ZBLAN • Pump 645 nm Lase 550 nm • Erbium (Er) doped ZBLAN • Pump 800 nm Lase 540 nm
Microspheres • Whispering Gallery Modes • Light traveling within surface boundary reflected at small angles • Best way of achieving low losses
Pump Laser • Argon ion pumping a dye laser • Unable to get dye laser to lase • Pumps at 645 nm • Argon ion pumping Ti:sapphire laser • Pumps at ~800 nm
Possible tests • Visual test – should see green • Spectrum with spectroscope to confirm visual test • Power in/out
Results • Unfortunately not able to get microsphere to lase. • Measured wavelength of pump laser -> 800.6 nm • Measured power of pump laser -> 240 mW
Possible explanations • Unable to correctly couple the laser into the microsphere • Hitting sphere head on possibly canceling out photons inside of microsphere • Created a bad microsphere
Challenges • Finding correct etching process • Dye Laser • Size of fibers
Successes • Refined process of etching fibers • Creation of microspheres
Future work • Get microsphere to lase • Couple multiple microspheres and collect data. • Creating an array of microspheres and getting them to lase.