Theoretical Investigation of an Optical Vibration Using Laser Beams from Optical Fibers Inserted at an Angle of 35 Degrees

Abstract

Optical trapping is a technique that is used to capture, translate, and manipulate microscopic particles, such as dielectric microspheres and cells. This cell manipulation and examination technology can be integrated on a Lab-on-a-Chip device. We have already developed an optically vibration system. The optical vibration system was formed using a temperature stabilized 1480nm cw diode laser. The output of laser light was coupled into optical fibers, which had optical connectors at these fiber ends. The fiber end had a hemispherical micro-lens with 5μm radius of curvature for focusing the laser beam emerging from the optical fiber end. These trapping fibers were attached to xyz manipulators and were inserted into a sample cell at an angle of 35 degrees. The trapped microsphere, 10μm diameter polystyrene particle (refractive index 1.59), could be optically vibrated by controlling laser power emerging from optical fibers. We theoretically analyzed the optical forces exerted on a microsphere by laser beams. Its operating principle is based upon the conservation of photon momentum carried by the incident laser light on a trapped microsphere. From these theoretical results, we verified that our proposed optical manipulation technique was useful for the manipulation of biological cells.