Perfect Optical Vortex to Produce Controllable Spot Array

Controllable motion of optical vortex arrays using electromagnetically induced transparency.

We demonstrate control of the collective motion of an optical vortex array using an electromagnetically induced transparency media. Scanning the frequency detuning between the pump and probe fields changes the susceptibility of the media, producing a unique effective diffraction of the vortex array for each detuning. We measure several experimental configurations and compare them to numerical s...

Optical phased array radiating optical vortex with manipulated topological charges.

Optical antennas are key elements in quantum optics emitting and sensing, and behave wide range applications in optical domain. However, integration of optical antenna radiating orbital angular momentum is still a challenge in nano-scale. We theoretically demonstrate a sub-wavelength phased optical antenna array, which manipulates the distribution of the orbital angular momentum in the near fie...

Efficient generation of a perfect optical vortex by using a phase optical element

We consider generation of a perfect optical vortex by three elements: (i) amplitude-phase element with its transmission being proportional to the Bessel function, (ii) optimal element with the transmission proportional to the sign of the Bessel function, and (3) helical axicon. Maximal intensity of light on the ring is shown to be achieved by using the optimal element. Thickness of the light ri...

Controllable vortex chirality switching on spherical shells

Robust Spot Fitting for Genetic Spot Array Images

In this paper we address the problem of reliably fitting parametric and semi-parametric models to high density spot array images obtained in genetic expression experiments. The goal is to measure the amount of genetic material at specific spot locations. A lot of spots can be modelled accurately by a Gaussian shape. In order to deal with highly overlapping spots we use robust M-estimators. When...