Acoustically Induced Phase and Intensity Modulation in Optical Fibers.
JOHN CARROLL UNIV CLEVELAND OHIO DEPT OF PHYSICS
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Studies have been made on the use of long length, low-loss optical fiber coils as direct acoustic sensors. The theory of optical mode propagation in step index fibers is briefly presented. Phase modulation theory is considered and then applied to a fiber that propagates only the first four optical modes. The results of this theory are then compared to experimental data obtained using such a fiber. When a fiber coil is exposed to a sinusoidal pressure variation in water two phase modulation processes are easily detected. The first is due to interference between directly transmitted and back and forth reflected beams. The second arises because of interference between two propagating modes in the fiber. Data obtained on these two processes are discussed in detail. Experimental data is also presented on intensity modulation effects detected in several different multimode step index fibers. Author
- Acoustic Detection and Detectors
- Fiber Optics and Integrated Optics