Creating an Exotic New Form of Light with Simple Optical Elements

Airy beams are non-diffracting optical beams first predicted by Berry and Balazs in 1979 and first demonstrated experimentally by Siviloglou, Broky, Dogariu, and Christodoulides in 2007. What makes an Airy beam unique is that it can be created in one dimension and that its lobe of highest intensity propagates along a parabolic path. Airy beams can be used for a variety of purposes including particle guidance, remote sensing and plasma channel generation. Airy beams are typically generated using specialized optical devices such as spatial light modulators (SLMs) or cubic phase masks. Besides cost, both of these specialized methods have limitations: an SLM cannot be used with a high-power laser, and a cubic phase mask is not tunable. An alternative method which is both simple and inexpensive and also not subject to these limitations is to exploit aberrations found in ordinary lenses in order to produce the required cubic phase modulation of the wavefront (Papazoglou, Suntsov, Abdollahpour, and Tzortzakisin, Physical Review A, 2010). In our research, we used the method of Papazoglou et al. to create a high-quality Airy beam. The setup included a 635 nm fiber-coupled diode laser with a collimating lens and negative and positive 80 mm focal length cylindrical lenses. Tilting and displacing the negative lens creates a coma aberration (cubic phase modulation); the subsequent positive lens removes aberrations other than the coma and roughly collimates the beam. The resulting wavefronts were imaged with a 200 mm focal length cylindrical Fourier transform lens into a Thorlabs DCC1545M CMOS camera and analyzed with ImageJ software. The transverse deflection of the highest-intensity lobe of the beam was observed by moving the camera along a linear rail to positions within a few cm of the focal plane. Were able to clearly demonstrate the nondiffracting and parabolic propagation of the beam. We found remarkable agreement with theoretical predictions the observed parabolic acceleration was perfectly predicted by the observed minimum size of the beam. We hope to continue our work on Airy beams by using the current setup to demonstrate the self-healing properties of the beam, using a similar setup with mirrors instead of lenses, thereby allowing a much broader range of electromagnetic radiation to be used to create Airy beams, and to model the wavefront of the generation an Airy beam.