Magnetic Force and Laser Excitation of Transverse Oscillations in Optical Microfibers

It is showed the possibility of contactless excitation of transverse oscillations in quartz optical microfibers (fiber microguides) due to their diamagnetic properties. The microguides are made from standard optical fibers by chemical etching and thermal drawing in an electric discharge arc. Dependences were found of resonance frequencies and Q factors of transverse oscillation modes of microguides on the ambient air density in a wide range of values corresponding to a pressure of 5 to 10⁵ Pa. Laser excitation of transverse oscillations in microguides was implemented and possible mechanisms of this excitation are discussed. It was found that in vacuum the resonance frequencies of transverse oscillations in microguides under laser excitation conditions are noticeably higher than in the case of magnetic force excitation of oscillations. The magnetic force excitation of microguide oscillations is shown to be possible at significant distances (~1 mm) between a microguide and the source of inhomogeneous magnetic field. These findings can serve as a basis for the development of new types of optical fiber modulators controlled by magnetic field and/or laser radiation and for the design of resonant optical fiber optic sensors with sensitive elements, based on optical microfibers.