Spatially coherent multicolored optical vector vortex beams were created using a tunable liquid crystal q-plate and a supercontinuum light source. The feasibility of the q-plate as a tunable spectral filter (switch) was demonstrated, and the polarization topology of the resulting vector vortex beam was mapped. Potential applications include multiplexing for broadband high-speed optical communication, ultradense data networking, and super-resolution microscopy.

Optical transmission through a spiral phase plate is analyzed by treating the device as a Fabry-Perot etalon with an azimuthally varying thickness. The transmitted beam is calculated to contain a coherent superposition of optical vortices with different winding numbers. This yields an intensity profile with a periodic modulation as a function of azimuthal angle where the orientation rotates as a function of the laser frequency. These effects are quantified experimentally and theoretically.

The spiral phase plate etalon transmission function is calculated from the low-reflectivity to high-reflectivity regime. Two approximations are considered: thick-plate approximation and thin-plate approximation. The thick-plate approximation explicitly takes into account the angle between the azimuthally increasing surface and the flat surface, while the thin-plate approximation does not. The two results are in agreement in the low-reflectivity regime, but not in the high-reflectivity regime. The thick-plate approximation is expected to provide a more accurate and general description of the device in all regimes. Origins of the device output intensity dependence on angle due to multiple vortex states present in the device are discussed, and a constraint on the number of internal reflections due to device geometry is also discussed.

Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 08/25/2015 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspxAbstract. This work presents propagation dynamics of structured light (complex light) containing optical vortices after it has undergone multiple reflections in a spiral phase plate (SPP) device having a nonzero surface reflection. In the calculations, the thick-plate approximation is assumed as it is expected to give a more accurate representation of the standard geometry of an SPP device from a low-surface reflection to a high-surface reflection. Calculations showing the propagation of counter-rotating optical vortices are presented, and the effect of the statistical nature of photons on the observation of the angular intensity modulation of the beam is discussed. Rumala: Propagation of structured light beams after multiple reflections in a spiral phase plate Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 08/25/2015 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx Optical Engineering 111306-8 November 2015 • Vol. 54(11) Rumala: Propagation of structured light beams after multiple reflections in a spiral phase plate Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 08/25/2015 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx