We present an experimental study of the coherence properties of amplified slow light by four-wave mixing (FWM) in a three-level electromagnetically induced transparency (EIT) system driven by one additional pump field. High energy gain (up to 19) is obtained with a weak pump field (a few mW/cm2) using optically dense cold atomic gases. A large fraction of the amplified light is found to be phase incoherent to the input signal field. The dependence of the incoherent fraction on pump field intensity and detuning and the control field intensity is systematically studied. With the classical input pulses, our results support a recent theoretical study by Lauk et al. [Phys. Rev. A88, 013823 (2013)], showing that the noise resulting from the atomic dipole fluctuations associated with spontaneous decay is significant in the high gain regime. This effect has to be taken into consideration in EIT-based applications in the presence of FWM.
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http://dx.doi.org/10.1364/OL.39.003394 | DOI Listing |
Ann Thorac Cardiovasc Surg
January 2025
Department of Cardiovascular Surgery, Kobe University, Kobe, Hyogo, Japan.
Purpose: In totally endoscopic off-pump left atrial appendage (LAA) closure and surgical ablation, securing the operative field is sometimes difficult in some patients because of a narrow working space caused by an elevated diaphragm or ventricles. In this study, we aimed to investigate the effectiveness of a method that facilitates securing the operative field using an artificial pneumothorax.
Methods: We analyzed 71 consecutive patients who underwent totally endoscopic off-pump LAA closure and bilateral pulmonary vein isolation.
Optical nonreciprocal devices are critical components in integrated photonic systems and scalable quantum technologies. We propose an all-optical approach to achieve integrated optical nonreciprocity utilizing a moving index grating. The grating is generated in a nonlinear optical waveguide through the Kerr effect by driving the waveguide with two counter-propagating pump fields of slightly different frequencies.
View Article and Find Full Text PDFLarge energy single-frequency nanosecond (ns) near-infrared light source is an essential device in the field of the remote chemical analysis based on the laser-induced breakdown spectroscopy (LIBS). In this paper, a large energy single-frequency ns 824 nm light source with high repetition rate is presented, which is generated from a seed-injection locked optical parametric oscillator (OPO). By optimizing the spot radius of the pump laser and the mode-matching between the pump laser and signal light, the optical parametric generation (OPG) process is effectively eliminated.
View Article and Find Full Text PDFWe provide the first direct experimental evidence for the reorientation of liquid crystals by polarized radiation from a conventional, low power, oscillator-based terahertz time-domain spectrometer. Using a terahertz pump - optical probe setup, we observed that the reorientation occurs locally through the resonant amplification of the terahertz field in a specially designed planar metamaterial, adjacent to the liquid crystal layer, and increases with increasing incident terahertz intensity. Our work thus demonstrates that it is possible to induce strong optical nonlinearity in liquid crystals in the terahertz part of the spectrum, paving the way toward the development of new all-optical active terahertz devices as well as electric field sensors for localized resonant systems.
View Article and Find Full Text PDFThe third harmonic (TH) signals in subwavelength scale devices have a wide range of applications, including nano-laser, microscopic imaging, sensing, and so on. However, the limited TH signal intensity still restricts practical applications due to the inherently small nonlinear coefficient in material and relatively weak confinement of the pump electromagnetic field. Here, we present the enhancement of TH signals in the isotropic Si nanosphere and the Au core/Si shell nanosphere exhibiting anapole mode excited by tightly focused radially polarized beams.
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