Direct current in semiconductor is theoretically shown. to be capable of doubling the frequency of the incoming optical radiation, The second order susceptibility, proportional to the current is calculated to be in th...
Direct current in semiconductor is theoretically shown. to be capable of doubling the frequency of the incoming optical radiation, The second order susceptibility, proportional to the current is calculated to be in the 10(-14) - 10(-13) m/V range, Applications of the novel phenomenon in probing and mapping of the current in semiconductor devices are considered. (C) 1995 American Institute of Physics.
The interference between two optical fields with nonzero spectral linewidths forms multiple moving space-charge fields inside photoconductive semiconductors that contain deep-level donors and traps. The de components ...
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The interference between two optical fields with nonzero spectral linewidths forms multiple moving space-charge fields inside photoconductive semiconductors that contain deep-level donors and traps. The de components of the photocurrents generated can be expressed in terms of a convolution of a function that is characteristic of the crystal and the signal optical power spectrum when the other optical field (local oscillator) has a negligible linewidth. This permits the recovery of the optical signal power spectrum.
We establish a new necessary and sufficient condition for a multivariate Gaussian random process to be reciprocal. This result is then used to prove that the state vector of a two-point boundary value system is recipr...
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We establish a new necessary and sufficient condition for a multivariate Gaussian random process to be reciprocal. This result is then used to prove that the state vector of a two-point boundary value system is reciprocal. We do not impose any nonsingularity conditions on the covariance function of the state vector.
Eigenmodes of three-wave interactions in second-order [chi(2)] nonlinear materials are explored that have a no-energy-exchange property between all the waves. They are shown to exhibit cross-induced nonlinear refracti...
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Eigenmodes of three-wave interactions in second-order [chi(2)] nonlinear materials are explored that have a no-energy-exchange property between all the waves. They are shown to exhibit cross-induced nonlinear refraction and to be ideal candidates for amplitude-dependent phase control in chi(2) materials that emulate nonlinear refractive-index effects in third-order [chi(3)] materials. It is shown that all these eigenmodes are spatially stable.
The massive and continuous spread of COVID-19 has motivated researchers around the world to intensely explore,understand,and develop new techniques for diagnosis and *** lung ultrasound imaging is a less established a...
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The massive and continuous spread of COVID-19 has motivated researchers around the world to intensely explore,understand,and develop new techniques for diagnosis and *** lung ultrasound imaging is a less established approach when compared to other medical imaging modalities such as X-ray and CT,multiple studies have demonstrated its promise to diagnose COVID-19 *** the same time,many deep learning models have been built to improve the diagnostic efficiency of medical *** integration of these initially parallel efforts has led multiple researchers to report deep learning applications in medical imaging of COVID-19 patients,most of which demonstrate the outstanding potential of deep learning to aid in the diagnosis of *** invited review is focused on deep learning applications in lung ultrasound imaging of COVID-19 and provides a comprehensive overview of ultrasound systems utilized for data acquisition,associated datasets,deep learning models,and comparative performance.
Equations that describe the steady-state dependence of the coherent-coupling properties of photorefractively induced refractive-index gratings on high-speed periodic biphase, sinusoidal, and triangular phase modulatio...
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Equations that describe the steady-state dependence of the coherent-coupling properties of photorefractively induced refractive-index gratings on high-speed periodic biphase, sinusoidal, and triangular phase modulation impressed on one of the input optical beams are found and solved for both depleted and undepleted pump conditions. The period of the phase modulation wave form was kept short compared with the grating-formation time but did not cause significant spectral broadening. The results obtained were verified with data obtained from measurements of two-wave mixing in the photorefractive material, InP:Fe.
We describe how two-wave mixing of light scattered at the entrance face of a photorefractive crystal can be used to measure the frequency difference between two independent lasers. This method can be used to accomplis...
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We describe how two-wave mixing of light scattered at the entrance face of a photorefractive crystal can be used to measure the frequency difference between two independent lasers. This method can be used to accomplish initial frequency acquisition in coherent optical homodyne receivers.
This paper addresses the following problem: Suppose a communication channel is to be set up between two points inside a simple polygon whose sides are opague to the transmission. The transmission originates at a point...
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This paper addresses the following problem: Suppose a communication channel is to be set up between two points inside a simple polygon whose sides are opague to the transmission. The transmission originates at a point s, called source, and is to be received at a point d, called destination. Clearly, a direct communication is impossible unless the points s and d are in sight of each other inside the polygon. Therefore, some repeaters (mirrors, for instance, if the transmission is optical in nature) are to be installed inside the polygon to make the communication feasible. What is the minimum number of repeaters required? The author introduces key lemmas that lead to an efficient algorithm for a minimum link path. An algorithm for finding a minimum link path is also presented.
Acoustic pulses have been generated in both metals and nonmetals using a low‐energy tunable dye laser emitting 6‐ns pulses with 20–210‐μJ energies. The acoustic waveforms have been detected optically with a calib...
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Acoustic pulses have been generated in both metals and nonmetals using a low‐energy tunable dye laser emitting 6‐ns pulses with 20–210‐μJ energies. The acoustic waveforms have been detected optically with a calibrated laser interferometer having improved signal‐to‐noise ratio. In this fashion, noncontact characterization of nonmetallic, as well as metallic samples of small size, has been shown to be feasible, using a potentially portable system. In addition between the relationship acoustic signal level and incident laser energy (and power density) has been measured for a polyimide‐glass‐fiber composite material.
Due to tiny relativistic effects, a host of nonlinear interactions of microwave or optical radiation with a single trapped electron in a strong magnetic field is feasible. This phenomenon, relativistic so-called nonli...
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Due to tiny relativistic effects, a host of nonlinear interactions of microwave or optical radiation with a single trapped electron in a strong magnetic field is feasible. This phenomenon, relativistic so-called nonlinear optics of a single electron, includes hysteretic and isolas resonances and various multiphoton excitations, in particular, stimulated cyclo-Raman resonances and subharmonics of any order. The authors develop a unified approach to all these effects. Results valid for arbitrary electron energy and for any order of interaction are obtained, and higher order cyclo-Raman resonances are predicted.< >
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