Frozen Waves: Longitudinal Patterning of Twisted Light

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Summary of Proposal for Public Release:***Conventional optical beams suffer from diffraction i.e., the spatial size of the beam, measured in a plane transverse to its direction of propagation, increases with the propagation distance. They also suffer from attenuation when traveling in an absorbing medium and scatter from small objects in their path (i.e. change their original direction). On the other hand, Frozen waves (FWs) and Modified Frozen Waves (MFWs) are a class of optical beams, which not only address the aforementioned shortcomings over a predefined finite distance, but perhaps more intriguing will allow the user to shape and modify the beam's intensity along its direction of propagation (i.e., along the beam's optical axis.) Moreover, MFW can carry angular momentum (spin or orbital) which means they can impart torque and rotation to small objects on their path.*** In this proposal, we further develop the theory of MFWs and we will investigate their applications in optical micromanipulation and sensing. In particular, we will examine the possibility of observing optical torsions in cells; in which oppositely directed torques are applied to the two-ends of a cell in a motion similar to squeezing water from a wet towel. Information gathered from biomechanical properties of cells is extremely important in determining cells' health and pathology. Moreover, we will use the orbital angular momentum properties of the MFWs to sense and measure the index of refraction associated with various liquids and gases.