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Berry’s Phase in Single Mode Optical Fiber. PHY 243W Advanced Lab Chris McFarland Ryan Pettibone Emily Veit. Theory. Berry’s Phase is a geometric phenomenon the can manifest itself in optics, quantum mechanics and even classical mechanics.
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Berry’s Phase in Single Mode Optical Fiber PHY 243W Advanced Lab Chris McFarland Ryan Pettibone Emily Veit
Theory • Berry’s Phase is a geometric phenomenon the can manifest itself in optics, quantum mechanics and even classical mechanics. • It occurs when more than one physical parameter of the particle’s path are changed adiabatically. • Although the parameters are returned to their original values the measured quantity (spin or polarization) does not. • EXAMPLE: Two parameters characterizing an EM wave could be the polar and azimuthal angle of the wave’s propagation vector!
Ein Eout Manifestation of Theory • As we all know {k,E,B} constitutes an orthogonal basis. • The optical fiber parallel transports the basis. • Linearly polarized light enters the optical fiber in one direction, exits in same direction, but plane of polarization is different!
Reflectors Polarizer Single-Mode Fiber Optic Cable Tube He-Ne Laser Oscilloscope Polarizer Photo-Detector Experimental Setup
N Side View Ein Eout Experimental Setup • The helix is uniform and has pitch angle and N turns: • The plane of polarization rotation angle is given theoretically by: =360°N(1-cos)
Experimental Issues We felt that there were two main sources of error: • The “Dandruff Effect:” Noise is created by air currents and tiny dust particles blocking the laser. • SOLUTION: Create a tunnel around the laser • Slack in the Cable: Berry’s phase can occur in the optical fiber. • SOLUTION: Lay the fiber flat
Experimental Issues • not large enough to measure accurately • SOLUTION: Increase N to amplify since is proportional to N.
Conclusion • Qualitatively observing the effect of Berry’s phase by manipulation of the optical fiber was relatively easy. • However, the next group working on this should be careful to eliminate aforementioned errors if they wish to obtain results approximating theoretical results. • Our data matches the theoretical results closely, providing strong evidence for the Berry’s phase hypothesis.