Arkady Rudnitsky

Nano photonic and ultra fast all-optical processing modules

In this paper we present an all-optical approach allowing the realization of logic gates and other building blocks of a processing unit. The modules have dimensions of only few microns, operation rate of tens of Tera Hertz, low power consumption and high energetic efficiency. The operation principle is based upon construction of unconventional wave guiding nano-photonic structures which do not include non-linear materials or interactions. The devices developed and presented in this paper include logic diffractive phase detector, generalized diffractive phase detector, logic gates as AND, OR and NOT, amplitude modulator and analog adder/subtractor.

All-optical nano modulator on a silicon chip.

We present an all-optical modulator realized on a silicon chip. The proposed modulator has nano scale dimensions and a high extinction ratio. Its operation principle is based on a spatially non-uniform variation of the absorption of a miniaturized, silicon waveguide - based Mach-Zehnder interferometer (MZI). The absorption variation is obtained by illuminating the MZI with visible light. Our modulator may be used as an interfacing link between microelectronic processing circuits and optical information transmission links. We provide details on the fabrication and the experimental characterization of the suggested device. Since the operation principle is not based on a high Finesse resonator, the modulator is less sensitive to wavelength changes and its operation rate is not connected to the time required for the optical response to reach steady state but rather to material related effects.

All-optical linear reconfigurable logic with nonlinear phase erasure

We introduce a novel all-optical logic architecture whereby the gates may be readily reconfigured to reprogram their logic to implement (N)AND/(N)OR/X(N)OR. A single gate structure may be used throughout the logic circuit to implement multiple truth tables. The reconfiguration is effected by an optical reference signal. The reference may also be adapted to an arbitrary Boolean complex alphabet at the gate logic inputs and calibrated to correct gate imperfections. The all-optical gate structure is partitioned into a linear interferometric front end and a nonlinear back end. In the linear section, two optical logic inputs, along with a reference signal, linearly interfere. The nonlinear back end realizes a phase-erasure (or phase-reset) function. The reconfiguration and recalibration capabilities, along with the functional decoupling between the linear and nonlinear sections of each gate, facilitate the potential aggregation of large gate counts into logic arrays. A fundamental lower bound for the expended energy per gate is derived as 3hnu+kT ln2 Joules per bit.

All-optical integrated micro logic gate

In this paper we present a novel approach for realizing an integrated all-optical logic gate. The basic principle is based upon stimulated emission process generated in an active gain medium while special interferometric photonic wave-guiding structure allows the realization of an integrated micro scale device. The operation rate of the proposed device structure can theoretically reach tens of Tera-Hertz.

Implantable photonic devices for improved medical treatments

Abstract. An evolving area of biomedical research is related to the creation of implantable units that provide various possibilities for imaging, measurement, and the monitoring of a wide range of diseases and intrabody phototherapy. The units can be autonomic or built-in in some kind of clinically applicable implants. Because of specific working conditions in the live body, such implants must have a number of features requiring further development. This topic can cause wide interest among developers of optical, mechanical, and electronic solutions in biomedicine. We introduce preliminary clinical trials obtained with an implantable pill and devices that we have developed. The pill and devices are capable of applying in-body phototherapy, low-level laser therapy, blue light (450 nm) for sterilization, and controlled injection of chemicals. The pill is also capable of communicating with an external control box, including the transmission of images from inside the patient’s body. In this work, our pill was utilized for illumination of the sinus-carotid zone in dog and red light influence on arterial pressure and heart rate was demonstrated. Intrabody liver tissue laser ablation and nanoparticle-assisted laser ablation was investigated. Sterilization effect of intrabody blue light illumination was applied during a maxillofacial phlegmon treatment.

A Self-Powered Medical Device for Blood Irradiation Therapy

Implantable wireless devices may allow localized real-time biomedical treating and monitoring. However, such devices require a power source, which ideally, should be self-powered and not battery dependent. In this paper, we present a novel self-powered light therapeutic device which is designed to implement blood irradiation therapy. This device is self-powered by a miniaturized turbine-based generator which uses hydraulic flow energy as its power source. The research presented in this paper may become the first step towards a new type of biomedical self-operational micromechanical devices deployed for biomedical applications.

Cascadable and reconfigurable photonic logic gates based on linear lightwave interference and non-linear phase erasure

Feasibility of cascading and reconfiguring a pair of linear-nonlinear all-optical logic gate structures is experimentally demonstrated using RF photonics. Progress in highly integrated O/E/O repeaters over Si/InP hybrid platforms enables large-scale reconfigurable gate arrays.

Home-use cancer detecting band aid

In this paper we present a novel concept in which special band aid is developed for early detection of cancer. The band aid contains an array of micro needles with small detection array connected to each needle which inspects the color of the surface of the skin versus time after being pinched with the needles. We were able to show in pre-clinical trials that the color varies differently if the skin is close to tumor tissue.

Collimated backlight for displays and micro-projectors

A backlight illuminator with low divergence angle will significantly improve the efficiency, contrast and color gamut of liquid-crystal displays (LCDs) and micro-projectors. However, converting light from a light-emitting diode (LED) with large angle of divergence into a low-angle of divergence beam using a device that is only a few mm thick is extremely challenging task. Here, we propose a novel solution to this problem by using an optimized light-guide collimator and a quasi-diffractive-optical element. The idea is to illuminate the screen with LED through a parabolic waveguide/funnel that converts a point source into a collimated beam with relatively small diameter. The collimated beam at the output of the parabolic collimator is aligned at an angle to a prismatic quassi diffractive optical element (DOE) fabricated on top of a piece of glass. The illumination at an angle increases the size of the illuminating spot and the goal of the DOE is to correct the propagation direction of the illuminating beam. The proposed concept is demonstrated via preliminary numerical and experimental results.

Fully Integrated Magneto Optic in Fiber Micro Modulator

In this paper we present the construction and the preliminary testing of an integrated magneto optic in-fiber modulator. The modulation concept is based upon insertion of Fe micro particles into holes drilled in an optical single mode fiber reaching the fiber’s core, and spatial translation of the particle in the hole, by means of external alternating magnetic field. Preliminary results show an extinction ratio of about -4dB.