Gregory J. Gbur

Simulating fields of arbitrary spatial and temporal coherence.

Optical coherence theory typically deals with the average properties of randomly fluctuating fields. However, in some circumstances the averaging process can mask important physical aspects of the field propagation. We derive a new method of simulating partially coherent fields of nearly arbitrary spatial and temporal coherence. These simulations produce the expected coherence properties when averaged over sufficently long time intervals. Examples of numerous fields are given, and an analytic formula for the intensity fluctuations of the field is given. The method is applied to the propagation of partially coherent fields through random phase screens.

Diffraction of evanescent waves and nanomechanical displacement detection

Sensitive displacement detection has emerged as a significant technological challenge in mechanical resonators with nanometer-scale dimensions. A novel nanomechanical displacement detection scheme based upon the scattering of focused evanescent fields is proposed. The sensitivity of the proposed approach is studied using diffraction theory of evanescent waves. Diffraction theory results are compared with numerical simulations.

Use of Nonconventional Incoherent Beam Arrays for Reduction of Turbulence-induced Scintillation

General guidelines for use of nonconventional incoherent beam arrays in scintillation reduction are explored; with these a new beam class is considered and the scintillation of the corresponding incoherent beam array is significantly reduced.

Construction of arbitrary vortex and superoscillatory fields

Superoscillations, oscillations of a bandlimited signal at frequencies greater than its band limit, have been verified both theoretically and experimentally. The design of such superoscillatory waves, however, has typically relied on complicated mathematics. We introduce a simple Fourier method to construct superoscillations in the transverse plane of an optical field in the form of optical vortices.

Partially Coherent Vortex Beams of Arbitrary Order

Analytic solutions for partially coherent vortex beams (PCVBs) of any azimuthal order are presented. Coherence and singular properties of these beams and their possible use in free-space optical communication are discussed.

Spatial Coherence Modulation with a Subwavelength Plasmonic Hole Array

We have investigated the spatial coherence properties of light on transmission through a subwavelength metallic hole array which supports surface plasmons. It shows that the modulation of such properties strongly depends on the array geometry.

Reduction of Turbulence-induced Scintillation by Nonuniformly Polarized Beam Arrays

We have investigated scintillation properties of nonuniformly polarized beam arrays. It is shown that turbulence-induced scintillation can be significantly reduced by such arrays whose nonuniformly polarized beamlets have optimized scintillation properties.

Phase Singularities in Partially Coherent Wavefields

Though partially coherent wavefields do not possess a deterministic phase, their correlation functions can possess zeros with nontrivial phase structures in their neighborhood. We discuss the optics and possible applications of such singularities.

Plasmonic Modification of Temporal Coherence

Through simulations and a simple model, it is demonstrated that the temporal coherence of a wavefield can be modified by surface plasmons. The effect is analogous to correlation-induced spectral changes.