Creating and controlling non-Rayleigh speckles

Speckles, or spatially random light fields, occur in both classical or quantum waves. They can be heard in radio static and seen on ripples in the ocean surface.

Researchers commonly use Rayleigh statistics when characterizing the physics of speckles. Bender et al. investigated non-Rayleigh speckles by developing a new method to control, create, and study them.

The authors developed a method to both control the intensity probability distribution function of speckle and their long range spatial intensity correlations. This means that they can modify the speckles’ topology and the formation of partial order in the speckle patterns, as illustrated in the top image of this article.

To control the complex light, the authors shined a uniform laser beam onto a controllable scattering surface called a spatial light modulator.

“With a spatial light modulator, we can arbitrarily create different random scattering surfaces which produce speckle patterns on a CCD camera,” author Nicholas Bender said. “By precisely encoding high-order correlations into the surface generating a speckle pattern, we can control the statistical properties of the speckle patterns measured by the camera.”

According to the authors, the new method is versatile and simple and should be suited for a large range of optical applications and experiments.

“Our method is advantageous because both the topology and the degree of spatial order in the speckled optical potentials are arbitrarily customizable and reconfigurable without any mechanical motion,” said Bender.

Source: “Creating and controlling complex light,” by Nicholas Bender, Hasan Yılmaz, Yaron Bromberg, and Hui Cao, APL Photonics (2019). The article can be accessed at https://doi.org/10.1063/1.5132960 .