Electronic Optical Phase Modulation

Abstract

Researchers at the University of Central Florida have developed a process using nonlinear optical procedures to exactly reverse the propagation direction and phase variation of a beam of light. Until now, purely optical techniques have been used to realize optical phase conjugation (OPC), which is used for many applications, ranging from laser medicine to imaging to communications. However, the classical approach is limited by its inability to adapt the phase conjugation quickly and precisely. Now, using the UCF electronic optical phase modulation (E-OPC) process, optical transmission through complex media such as biological tissue, traditionally limited by multiple light scattering, can now be realized.

In laser medicine, this technique can fluorescently label a cell (such as a cancer cell) and use the advantages of OPC to selectively interact with these cells without effect to surrounding tissues. These actions can be thermal, mechanical or chemical, all mediated by the back propagated optical beam. This process can also be applied to defense applications where the light/electromagnetic waves come from objects of interest. Using this method, it is possible to use OPC to illuminate, interfere or destroy the object that was illuminated.

Technical Details

The UCF invention combines electronic and optical phase conjugation. Typically, there is an efficiency limitation due to phase conjugation relying on nonlinear optical processes. However, the invention resolves this issue by introducing electronic phase conjugation (E-OPC) as a complementary method. OPC defines a special relationship between two coherent optical beams propagating in opposite directions with reversed wavefronts and identical transverse amplitude distributions. The two-step process of E-OPC begins by measuring the wavefront of the signal wave (fluorescence) using a reference beam and charge-coupled device (CCD) arrays so that both quadratures of the wavefront are measured. The measured wavefront is then conjugated in the electrical domain and applied to a spatial modulator array that generates the phase modulated beam to back propagate to the sample. E-OPC removes the wavelength and efficiency limitation as CCDs respond over a broad spectrum and provides the unique ability to remove aberrations due to a turbid medium.

Benefit

Market Application