Zubin Jacob

Optical Hyperlens: Far-field imaging beyond the diffraction limit

We propose an approach to far-field optical imaging beyond the diffraction limit. The proposed system allows image magnification, is robust with respect to material losses and can be fabricated by adapting existing metamaterial technologies in a cylindrical geometry.

Semiclassical theory of the hyperlens

We study ray dynamics inside the hyperlens, a device recently demonstrated as capable of sub-diffraction-limited far-field imaging. The obtained semiclassical result of spiraling rays is confirmed by numerical simulations of Gaussian beam scattering from the hyperlens.

Semiclassical theory of the Hyperlens

We study ray dynamics inside the Hyperlens, a device recently demonstrated as capable of sub-diffraction-limited far-field imaging. The obtained semiclassical result of spiraling rays is confirmed by numerical simulations of gaussian beam scattering from the hyperlens.

Optical Hyperspace: Negative Refractive Index and Subwavelength Imaging

The art and science of optics is centered upon our ability to control the refractive index of materials, thereby directing the flow of light. From the stained-glass windows of Gothic cathedrals to modern LCD projectors, from Galileos telescope to terabit optical communication systems, devices made possible by skillful manipulation of the refractive index have resulted in countless technological and cultural breakthroughs. For centuries, the refractive index has been regarded as a strictly positive quantity âx80x94 such was the universal experience. Recent advances in fabrication and processing techniques, however, have enabled the creation of materials with a negative refractive index. This development opens many new chapters in the fields of optical physics and device engineering. Negative index greatly expands the parameter space accessible for manipulating light, opening the way for devices with unprecedented capabilities âx80x94 for example, imaging systems with subwavelength resolution and ultrasmall waveguides. The novel systems made possible by negative index materials (NIMs) may bring about revolutionary technological changes.nnIn the present chapter we describe a method to achieve negative refraction via materials with a hyperbolic dispersion relation. Both natural materials and metamaterials can exhibit this property. We show that in addition to providing a simple path to nonmagnetic negative refraction, the hyperbolic dispersion relation enables novel devices for waveguiding and subwavelength imaging.nnThe present-day interest in NIMs started in the early 2000s. The origins of the subject, however, date back many decades. Indeed, as a general wave propagation phenomenon, negative refraction has been known since the early 20th century. It was noted, in particular, that negative refraction naturally occurs at the interface with a medium characterized by negative phase velocity. No such materials were known in the electromagnetic domain, and so the early discussions involved only mechanical oscillations. The first detailed treatment of negative refraction in electromagnetism was provided by Veselago in 1968. He showed that to attain negative phase velocity for electromagnetic (EM) waves, the material response must be of the form Iµ < 0, I¼ < 0. When this condition is satisfied, the E, H, and k vectors form a left-handed triplet. As a result, the wave vector k and the Poynting vector S are oriented in opposite directions; the system has negative phase velocity, which is the condition for negative refraction. Indeed, negative phase velocity serves as a definition of negative index materials. While mechanical and radio frequency devices exhibiting such effective negative indices were known at the time of Veselagos writing, bulk materials with negative phase velocity were not found in nature and were not readily attainable.

Optical "Hyperlens": imaging in the far field beyond the diffraction limit

We propose a system for far field optical imaging below the diffraction limit. As opposed to the superlens based on negative index materials, our approach allows image magnification and is robust with respect to material losses.

Optical hyperlens: far-field imaging beyond the diffraction limit

We propose an approach to far-field optical imaging beyond the diffraction limit. The proposed system allows image magnification, is robust with respect to material losses and can be fabricated by adapting existing metamaterial technologies in a cylindrical geometry.

Semiclassical theory of hyperlensing and cloaking

We develop the ray optic Hamiltonian for a cylindrically anisotropic medium such as the hyperlens using the semiclassical approximation, which reveals an interesting spiralling behaviour of ray trajectories and also gives an alternative explanation to the subdiffraction far field imaging behaviour of the device. The Hamiltonian can be further used to derive the material parameters needed for non magnetic cloaking. Numerical simulations of gaussian beam scattering from these devices confirm the respective semiclassical results.

Asymmetric microdisk resonators: Using geometry to control evanescent field

The geometry of a microdisk resonator can be used to control the intensity of its evanescent field. Asymmetric microdisk devices can allow for substantial increase of the distance between the evanescently coupled elements of optoelectronic circuits.

Optical hyperspace : negative refractive index and subwavelength imaging in anisotroptic dielectric metamaterials

We propose an approach to far field optical imaging below the diffraction limit, based on dielectric metamaterials with strong anisotropy. As opposed to the superlens that relies on negative index materials, our method allows image magnification and is robust with respect to material losses.