Nowadays, dozens of anisotropic two-dimensional materials with diverse and highly tunable band structures have been discovered, exhibiting much richer optical functionalities, such as anisotropic absorption, luminescence, light detection, and hyperbolic polaritons, which provides a promising platform to explore and manipulate the light-matter interactions.
The image on the cover provides a visual rendering of the on-chip scheme for deterministic N-photon state generation in lithium niobate on insulator (LNOI) circuit, where deterministic parametric down-conversion (DPDC) and deterministic parametric up-conversion (DPUC) are realized through high-Q microring resonator and spiral waveguide, respectively.
An accurate quantitative phase imaging (QPI) technique based on pseudo-weak object approximation is proposed to achieve 3D quantitative measurements of both small-phase objects and large-phase objects by differential phase contrast without additional data acquisition.
Combining the special spatial distribution characteristics of the noble metal nanostructures with the special electrical-vector distribution characteristics of the azimuthal vector beam, the electrical nearfield intensity of the surface plasmonic mode localized near the noble metal nanostructures can be significantly improved, thereby achieving high sensitivity Raman examination. This vector light-field enhanced Raman spectroscopy is expected to be applied to trace detection.
It is believed that the next grand information revolution could be brought by an exotic class of devices whose operation is based on spins as the information carrier. To unveil the ultimate speed limit and energy efficiency of spintronic devices, one needs to understand the dynamics of spins in their host matrix. The emergent time-resolved terahertz technology has become not only our most advanced camera to film spins in action but also a versatile toolkit for manipulating spin states unachievable by conventional means.
In this paper, we studied the dynamics of a dispersion-tuned swept-fiber laser both experimentally and theoretically. By adding a dispersion compensation
In this paper, we studied the dynamics of a dispersion-tuned swept-fiber laser both experimentally and theoretically. By adding a dispersion compensation fiber and an electro-optic modulator in the laser cavity, an actively mode-locked laser was obtained by using intensity modulation, and wavelength sweeping was realized by changing the modulation frequency. Using a high-speed real-time oscilloscope, the dynamic behaviors of the swept laser were investigated during wavelength switching, static-sweeping cycle, and continuous sweeping, respectively. It was found that the laser generates relaxation oscillation at the start of the sweeping mode. The relaxation oscillation process lasted for about 0.7 ms, and then the laser started to operate stably. Due to the nonlinear effect, new wavelengths were generated in the relaxation oscillation process, which is not beneficial for applications. Fortunately, relaxation oscillation disappears if the laser starts up and operates in the continuous sweeping mode, and the good sweeping symmetry between the positive sweep and negative sweep increases the application potential of the laser. In addition, the instantaneous linewidth is almost the same as that in the static state. These results describe the characteristics of the laser from a new perspective and reveal, to the best our knowledge, the intensity dynamics of such lasers for the first time. This paper provides some new research basis for understanding the establishment process of dispersion-tuned swept-fiber lasers and their potential application in the future.show less
Fifth-generation (5G) communication requires spatial multiplexing multiple-input multiple-output systems with integrated hardware. With the increase in th
Fifth-generation (5G) communication requires spatial multiplexing multiple-input multiple-output systems with integrated hardware. With the increase in the number of users and emergence of the Internet of Things devices, complex beamforming devices have become particularly important in future wireless systems to meet different communication requirements, where independent amplitude and phase modulations are urgently required for integrated beamforming devices. Herein, by utilizing the constructive interference between multiple geometric-phase responses, the mathematical relation for decoupling amplitude and phase modulations in the radiation-type operational mode is derived. Based on this strategy, complex-amplitude radiation-type metasurfaces (RA-Ms) are implemented, with an integrated feeding network. Such metasurfaces exploit full
Two-color plasma, induced by two lasers of different colors, can radiate ultra-broadband and intense terahertz (THz) pulses, which is desirable in many te
Two-color plasma, induced by two lasers of different colors, can radiate ultra-broadband and intense terahertz (THz) pulses, which is desirable in many technological and scientific applications. It was found that the polarization of the emitted THz depends on the phase difference between the fundamental laser wave and its second harmonic. Recent investigation suggests that chirp-induced change of pulse overlap plays an important role in the THz yield from two-color plasma. However, the effect of laser chirp on THz polarization remains unexplored. Hereby, we investigate the impact of laser chirp on THz polarization. It is unveiled that the chirp-induced phase difference affects THz polarization. Besides, positive and negative chirps have opposite effects on the variation of the THz polarization versus the phase difference. The polarization of THz generated by a positively chirped pump laser rotates clockwise with an increasing phase difference, while it rotates anticlockwise when generated by a negatively chirped pump laser.show less
Ultra-broadband, intense, coherent terahertz (THz) radiation can be generated, detected, and manipulated using laser-ionized gaseous or liquid media as both the THz wave emitter and sensor, with
Ultra-broadband, intense, coherent terahertz (THz) radiation can be generated, detected, and manipulated using laser-ionized gaseous or liquid media as both the THz wave emitter and sensor, with a bandwidth covering the entire “THz gap” and beyond. Such a research topic is termed as “plasma-based THz wave photonics in gas and liquid phases”. In this article, we review the most important experimental and theoretical works of the topic in the non-relativistic region with pump laser intensity below 1018 W/cm2.show less
A high-efficiency, low-threshold, high-repetition-rate H-β Fraunhofer line light at 486.1 nm was demonstrated. A high-efficiency KTP optical parametric oscillator was achieved by double-pass pum
A high-efficiency, low-threshold, high-repetition-rate H-β Fraunhofer line light at 486.1 nm was demonstrated. A high-efficiency KTP optical parametric oscillator was achieved by double-pass pumping with a high-maturity 5-kHz 532 nm laser. Thanks to the efficient intracavity frequency doubling of the circulating signal wave by a BIBO crystal, the threshold pump power of the 486.1 nm output was 0.9 W, and the maximum output power of 1.6 W was achieved under the pump power of 7.5 W. The optical-optical conversion efficiency was 21.3%, with the pulse duration of 45.2 ns, linewidth of ⁓0.12 nm, and beam quality factor M2 of 2.83.show less
Cavity quantum electrodynamics (QED) system is a promising platform for quantum optics and quantum information experiments. And its core is the strong coupling between atoms and optical cavity,
Cavity quantum electrodynamics (QED) system is a promising platform for quantum optics and quantum information experiments. And its core is the strong coupling between atoms and optical cavity, which causes difficulty in the overlap for the atoms and the antinode of optical cavity mode. Here, we use a programmable movable optical dipole trap to load a cold atomic ensemble into an optical fiber microcavity and realize the strong coupling between the atoms and the optical cavity in which the coupling strength can be improved by polarization gradient cooling and adiabatic loading. By the measurement of vacuum Rabi splitting, the coupling strength can be as high as gN = 2π×400 MHz, which means the effective atom number is Neff = 16 and the collective cooperativity is CN = 1466. These results show this experimental system can be used for cold atomic ensemble and cold molecule based cavity QED research.show less
In this paper, we demonstrated the phonon-assisted vibronic lasing of an Yb-doped sesquioxide Yb:LuScO3 crystal. The electron-phonon coupling process was analyzed and the Huang-Rhys factor S was
In this paper, we demonstrated the phonon-assisted vibronic lasing of an Yb-doped sesquioxide Yb:LuScO3 crystal. The electron-phonon coupling process was analyzed and the Huang-Rhys factor S was calculated to be 0.75 associated with the fluorescence spectrum at room temperature. By a rational cavity design to suppress lasing below 1100 nm, a continuously spectral tuneability from 1121 to 1136 nm was realized in Yb:LuScO3 laser, which represents the longest achievable wavelength in the Yb-doped sesquioxide lasers. Moreover, Raman spectrum indicated that the Eg phonon mode with a frequency of 472 cm-1 was mainly devoted to the phonon-assisted transition process. This work broadens the achievable laser spectrum of Yb-doped sesquioxide, and suggests the multiphonon-electron coupling strategy should be universal for other laser materials.show less