At the microscopic scale, the light matter interaction may organize colloidal matter due to a process known as optical
binding. Optical binding has now been established as an important issue for the assembly of colloidal matter by light. In
the paper we investigate one dimensional optically bound matter of microscopic objects. We develop a dual beam optical
fiber trap using a femtosecond laser where the peak power permits us to use two-photon excitation within the host
medium. In this trap we can visualize the field distribution in an optical bound array. A numerical model is presented
which provides a comparison between theory and experiment.
The emerging field of micro fluidics is challenged with a desire to pump, move and mix minute amounts of fluid. Such micro devices are operated by means of light matter interaction, namely they can be driven through utilizing birefringence and the polarization of the light as well as the reflection and refraction of light. The latter one enables micro motors to be operated in a tangential setup where the rotors are on axis with an optical waveguide. This has the advantage that the complexity of driving such a device in a lab on a chip configuration is reduced by delivering the driving light by means of a waveguide or fiber optics. In this publication we study a micro motor being driven by a fiber optically delivered light beam. We present experimentally and theoretically how light is getting diffracted when in interaction with the rotors of a turning micro motor. By utilizing the two photon signal from a fluorescein dye being excited by a pulsed femtosecond Laser which was used to drive the motor. Additionally the rotation rate is investigated in dependence of the light field parameters.
Raman Tweezers Micro Spectroscopy has become an important and versatile technique in recent years. The technique is the amalgamation of optical tweezers and traditional Raman spectroscopy. The combination of these two well established techniques has brought key advantages in the studies of many different physical and biological systems from studying drug distribution in cells to measuring the size of aerosol particles. In this paper we present our Raman Tweezers system and discuss its advantages over conventional Raman systems, also discussed in this section is the parameters which effect collection of Raman scattered light using the ability of the optical tweezers to stack micro spheres. Finally we discuss how to extend further the functionality of the Raman tweezers technique by decoupling the trapping and excitation with the use of a fibre optical light force trap.
Optical binding may arise due to interplay between light scattering and refraction creating equilibrium positions for particles in a self-consistent manner. Binding is observed for the first time in biological cells within a dual beam fiber trap.