Boris M. Chernobrod

Suppression of intensity fluctuations in free space high-speed optical communication based on spectral encoding of a partially coherent beam

A new concept of a free space, high-speed (Gbps) optical communication system based on spectral encoding of radiation from a broadband pulsed laser is developed. It is shown that, in combination with the use of partially coherent laser beams and a relatively slow photosensor, scintillations can be suppressed by orders of magnitude for distances of more than 10 km.

Measurement of single electron and nuclear spin states based on optically detected magnetic resonance

A novel approach for measurement of single electron and nuclear spin states is suggested. Our approach is based on optically detected magnetic resonance in a nano-probe located at the apex of an AFM tip. The method provides single electron spin sensitivity with nano-scale spatial resolution.

Improving the sensitivity of frequency modulation spectroscopy using nanomechanical cantilevers

It is suggested that nanomechanical cantilevers can be employed as high-Q filters to circumvent laser noise limitations on the sensitivity of frequency modulation spectroscopy. In this approach, a cantilever is actuated by the radiation pressure of the amplitude modulated light that emerges from an absorber. Numerical estimates indicate that laser intensity noise will not prevent a cantilever from operating in the thermal noise limit, where the high Q’s of cantilevers are most advantageous.

Single-spin microscope with sub-nanoscale resolution based on optically detected magnetic resonance

Recently we proposed a new approach which potentially has single spin sensitivity, sub-nanometer spatial resolution, and ability to operate at room temperature (J. Appl. Phys. 97, 014903 (2005); U.S. Patent No. 7,305,869, 2007). In our approach a nanoscale photoluminescent center exhibits optically detected magnetic resonance (ODMR) in the vicinity of magnetic moment in the sample related with unpaired individual electron or nuclear spins, or ensemble of spins. We consider as a sensor material that exhibit ODMR properties nitrogen-vacancy (N-V) centers in diamond. N-V centers in diamond has serious advantage having extraordinary chemical and photostability, very long spin lifetimes, and ability single-spin detection at room temperature. The variety of possible scanning schemes has been considered. The potential application to 3D imaging of biological structure has been analyzed.

Reduction of laser intensity scintillations in turbulent atmospheres using time averaging of a partially coherent beam

We demonstrate experimentally and numerically that the application of a partially coherent beam (PCB) in combination with time averaging leads to a significant reduction in the scintillation index. We use a simplified experimental approach in which the atmospheric turbulence is simulated by a phase diffuser. The role of the speckle size, the amplitude of the phase modulation, and the strength of the atmospheric turbulence are examined. We obtain good agreement between our numerical simulations and our experimental results. This study provides a useful foundation for future applications of PCB-based methods of scintillation reduction in physical atmospheres.

Uncooled infrared and terahertz detectors based on micromechanical mirror as a radiation pressure sensor

We consider midinfrared (5 - 25 μm) and terahertz (100 - 1000 μm), room-temperature detectors based on a microcantilever/micromirror sensor of the radiation pressure. The significant enhancement of sensitivity is due the combination of non-absorption detection and a high quality optical microcavity. Applications for spectrometry and imaging are analyzed. It is shown that the radiation pressure sensor potentially has sensitivity at the level of or better than the best conventional uncooled detectors.

Sensitivity Analysis of a Proposed Novel Opto-Nano-Mechanical Photodetector for Improving the Performance of LIDAR and Local Optical Sensors

We propose a novel approach to the development of a new generation of optical sensors with enhanced detection sensitivity for chemical species. The novelty comes from combining an extremely high Q cantilever sensor with an already well established very sensitive technique, frequency modulation (FM) spectroscopy. In existing implementations, this inherent sensitivity is limited by the inadequacy of current state-of-the-art electronic filters to differentiate the weak amplitude modulated (AM)signal from the inevitable high-frequency laser noise, a consequence of the deterioration in the quality factor with increasing frequency exhibited by these filters. Our approach combines FM techniques with the rapidly advancing technology of nano-mechanical resonator (cantilever) development. Here a cantilever functions as both a sensitive photodetector and a high-quality spectral or temporal filter. These ultra-low mass devices enable detection of the photon momentum rather than conventional detection by photon energy. At least one order of magnitude enhancement appears feasible with existing cantilever technology.

The effects of phase diffuser on scintillations of laser radiation for long-distance propagation in the atmosphere

We consider theoretically and numerically the suppression of fluctuations (scintillations) of a laser beam propagating through turbulent atmospheres by applying a phase modulator. Both spatial and temporal phase variations introduced by this phase modulator are analyzed. The explicit dependences of the scintillation index on the initial correlation length and finite-time phase variations for long propagation paths are obtained. Results of modeling and numerical simulations are presented. We demonstrate that an appropriately chosen phase modulator can significantly suppress the scintillations of the laser beam caused by turbulent atmospheres.

QUANTUM ENGINEERING FOR THREAT REDUCTION AND HOMELAND SECURITY

We review the results of our current research on quantum engineering which include the theory, modeling and simulations of quantum devices for potential applications to threat reduction and homeland security. In particular, we discuss: (i) scalable solid-state quantum computation with qubits based on (a) nuclear spins of impurity atoms in solids, (b) superconducting junctions, and (c) unpaired electron spins of spin radicals in self-assembled organic materials; (ii) quantum neural devices; (iii) quantum annealing; (iv) novel magnetic memory devices based on magnetic tunneling junctions with large tunneling magnetoresistance; (v) terahertz detectors based on microcantilever as a light pressure sensor; (vi) BEC based interferometers; (vii) quantum microscopes with a single-spin resolution based on (a) a magnetic resonant force microscopy and (b) an optically detected magnetic resonance; and (viii) novel approach for suppression of fluctuations in free space high-speed optical communication. Finally, we describe the similarities between the behavior of cross sections in reactions with heavy nuclei in the regions of strongly overlapped resonances and electron conductivity in semiconductor heterostructures.

IR photodetector based on an optically cooled micromirror as a light pressure sensor

We consider mid-infrared (5 - 25 μm), optically cooled detectors based on a microcantilever sensor of the radiation pressure. The significant enhancement of sensitivity is due the combination of low effective temperature (10 K), non-absorption detection and a high quality optical microcavity. Spectrometry applications are analyzed. It is shown that an optically cooled radiation pressure sensor potentially has an order of magnitude better sensitivity than the best conventional uncooled detectors.