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Study of Factors Affecting Performance of Spin-Polarized Atomic Gyroscopes. Uyen Nguyen Huynh Dr. Andrei M. Shkel Max Perez Jesper Eklund Monty Rivers Ilya N. Chepurko Marc Salleras. IM-SURE. Outline. Introduction Motivation Background on Thin-film Design
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Study of Factors Affecting Performance of Spin-Polarized Atomic Gyroscopes Uyen Nguyen Huynh Dr. Andrei M. Shkel Max Perez Jesper Eklund Monty Rivers Ilya N. Chepurko Marc Salleras IM-SURE
Outline • Introduction • Motivation • Background on Thin-film Design • Background on Polarized Light • Procedure • Results • Conclusion 2
Introduction B1cos(ωat) • NMRG: Nuclear Magnetic Resonance Gyroscope • Requires circularly polarized light and high optical power • Interest: optical properties at various α Static Field Bo Cross-section of assembled NMRG* Photodiode VCSEL Drawing by Jesper Eklund * John Kitching, Elizabeth Donley, Andrei M. Shkel, E. Jesper Eklund, and Eleanor Hodby, "Compact Atomic Magnetometer and Gyroscope Based on a Diverging Laser Beam," UC Case No. 2008-002, Patent pending.
NMR Cell • Coated with alternating layers of high and low indices of refraction • Filled with NMR gas 1.8mm Graphics and fabricated by Max Perez
Motivation • NMR Gyroscope performance affected by: • Circularly polarized light • Intensity of reflected light • Study the effects of multilayer reflectors and fabrication imperfection on reflectance and polarization state of light 5
Why Multi-Layer Thin-Film? nH*LH = nL*LL = λair/4 Air H L H L Si Image from http://en.wikipedia.org/wiki/Image:Optical-coating-2.png
Polarization States Image from http://www.thorlabs.com/Thorcat/12900/12973-D02.pdf
Experimental Procedure Poincare Sphere Sensor Sample ¼ Wave-Plate ½ Wave-Plate VCSEL λ = 795nm Full Cell ½ Cell
Power Split Ratio • Power Split Ratio: • 0 ≤ a ≤ 1 • Phase difference: • -180o ≤ ∆ ≤ 180o • Circularly Polarized light: • a = 0.5 • ∆ = ± 90o Image from http://www.thorlabs.com/Thorcat/12900/12973-D02.pdf
Test Samples • Bulk Silicon cell • 12 Si3N4-SiO2 layer cell (n = 2.0, 1.5) • 8 Si-SiO2 layer cell (n = 3.7, 1.5) • 6 Si-SiO2 layer cell • 6 Si-SiO2 layer wafer Graphics and fabricated by Max Perez 10
Results of 6-Layer Cell ½ NMR Cell Sensor VCSEL 11
Results of 6-Layer Wafer 6 Layer Wafer Sensor VCSEL 12
Analysis Results of the 6-Layer Cell Sensor ½ NMR Cell E0x VCSEL 13
Results of Double Reflection Graph and samples by Max Perez
Conclusion • Multi-layer thin-film design: • Improves cell’s reflectance to ~ 99% • Able to keep circularly polarized light inside cell • Fabrication imperfection: • Decreases reflectance of NMR cell • Varies phase difference significantly • Changes the polarization state of light inside cell • Improves reflectance compared to bulk Si cell 16
Acknowledgements NATIONAL SCIENCE FOUNDATION IM-SURE Managing Director : Said M. Shokair Faculty Mentor: Andrei M. Shkel, PhD. MicroSystems Lab Max Perez Jesper Eklund Monty Rivers Ilya N. Chepurko Marc Salleras 17