The image on the cover for Advanced Photonics Volume 4 Issue 2 illustrates a schematic of a Mueller matrix measurement system and a conceptional Mueller matrix of the sample (4x4 matrix), as well as the related vectorial properties of the light beams.The image is based on original research presented in the article by Chao He, Jintao Chang, Patrick S. Salter, Yuanxing Shen, Ben Dai, Pengcheng Li, Yihan Jin, Samlan Chandran Thodika, Mengmeng Li, Tariq Aziz, Jingyu Wang, Jacopo Antonello, Yang Dong, Ji Qi, Jianyu Lin, Daniel S. Elson, Min Zhang, Honghui He, Hui Ma, and Martin J. Booth, “ Revealing complex optical phenomena through vectorial metrics,” Adv. Photon. 4(2), 026001 (2022), doi 10.1117/1.AP.4.2.026001.
The image on the cover for Chinese Optics Letters Volume 20, Issue 4, indicates that an InAs/GaAs quantum dot photonic crystal bandedge laser, which is directly grown on an on-axis Si (001) substrate, which provides a feasible route towards a low-cost and large-scale integration method for light sources on the Si platform was achieved under the pumping condition of a continuous-wave 632.8 nm He–Ne gas laser at room temperature.The image is based on original research by Yaoran Huang et al. presented in their paper "Highly integrated photonic crystal bandedge lasers monolithically grown on Si substrates", Chinese Optics Letters 20 (4), 041401 (2022).
The image on the cover for Photonics Research Volume 10, Issue 3, demonstrates a correlated triple amplitude and phase holographic encryption based on an all-dielectric metasurface. An optimized holographic algorithm is developed to obtain quantitatively correlated triple holograms, which can encrypt information in multiple wavelength and polarization channels.The image is based on original research by Hongqiang Zhou et al. presented in their paper "Correlated triple hybrid amplitude and phase holographic encryption based on a metasurface", Photonics Research 10 (3), 03000678 (2022).
The image on the cover for Photonics Research Volume 10, Issue 2, demonstrates low-loss AlGaAs-on-SOI photonic circuits with integrated Si waveguides and showcase sub-milliwatt-threshold (∼0.25mW∼0.25mW) Kerr frequency comb generation in ultrahigh-??Q AlGaAs microrings (??Q over 106106) at the telecom bands.The image is based on original research by Weiqiang Xie et al. presented in their paper "Silicon-integrated nonlinear III-V photonics", Photonics Research 10 (2), 02000535 (2022).
It is experimentally verified that nonreciprocal photonic systems with continuous translation symmetry may have an ill-defined topology. The topological c
It is experimentally verified that nonreciprocal photonic systems with continuous translation symmetry may have an ill-defined topology. The topological classification of such systems is only feasible when the material response is regularized with a spatial-frequency cutoff. We experimentally demonstrate that adjoining a small air layer to the relevant material interface may effectively imitate an idealized spatial cutoff that suppresses the nonreciprocal response for short wavelengths and regularizes the topology. Furthermore, it is experimentally verified that nonreciprocal systems with an ill-defined topology may be used to abruptly halt the energy flow in a unidirectional waveguide due to the violation of the bulk-edge correspondence. In particular, we report the formation of an energy sink that absorbs the incoming electromagnetic waves with a large field enhancement at the singularity.show less
Probabilistically shaped (PS) high-order quadrature amplitude modulation (QAM) signals are attractive to coherent optical communication due to increased s
Probabilistically shaped (PS) high-order quadrature amplitude modulation (QAM) signals are attractive to coherent optical communication due to increased spectral efficiency. However, standard digital signal processing algorithms are not optimal to demodulate PS high-order QAM signals. Therefore, a compromise equalization is indispensable to compensate the residual distortion. Meanwhile, the performance of conventional blind equalization highly depends on the accurate amplitude radius and distribution of the signals. The PS high-order QAM signals make the issue worsen because of indistinct amplitude distributions. In this work, we proposed an optimized blind equalization by utilizing a peak-density K-means clustering algorithm to accurately track the amplitude radius and distribution. We experimentally demonstrated the proposed method in a PS 256-QAM coherent optical transmission system and achieved approximately 1 dB optical signal-to-noise ratio improvement at the bit error rate of
In order to reach the highest intensities, modern laser systems use adaptive optics to control their beam quality. Ideally, the focal spot is optimized af
In order to reach the highest intensities, modern laser systems use adaptive optics to control their beam quality. Ideally, the focal spot is optimized after the compression stage of the system in order to avoid spatio-temporal couplings. This also requires a wavefront sensor after the compressor, which should be able to measure the wavefront on-shot. At PHELIX, we have developed an ultra-compact post-compressor beam diagnostic due to strict space constraints, measuring the wavefront over the full aperture of 28 cm. This system features all-reflective imaging beam transport and a high dynamic range in order to measure the wavefront in alignment mode as well as on shot.show less
The use of silicon nitride in integrated photonics has rapidly progressed in recent decades. Ultra-low-loss waveguides based on silicon nitride are a favo
The use of silicon nitride in integrated photonics has rapidly progressed in recent decades. Ultra-low-loss waveguides based on silicon nitride are a favorable platform for the research of nonlinear and microwave photonics and their application to a wide variety of fields, including precision metrology, communications, sensing, imaging, navigation, computation, and quantum physics. In recent years, the integration of Si and III-V materials has enabled new large-scale, advanced silicon nitride-based photonic integrated circuits with versatile functionality. In this perspective article, we review current trends and the state-of-the-art in silicon nitride-based photonic devices and circuits. We highlight the hybrid and heterogeneous integration of III-V with silicon nitride for electrically pumped soliton microcomb generation and ultra-low-noise lasers with fundamental linewidths in the tens of mHz range. We also discuss several ultimate limits and challenges of silicon nitride-based photonic device performance and provide routes and prospects for future development.show less
Entanglement serves as a fundamental resource for quantum information protocols, and hyperentanglement has received an explosively increasing amount of attention for its high-capacity c
Entanglement serves as a fundamental resource for quantum information protocols, and hyperentanglement has received an explosively increasing amount of attention for its high-capacity characteristic. Increasing the scale of hyperentanglement, i.e., the number of modes in a hyperentangled system, is crucial for enhancing its capability in quantum information processing. Here we demonstrate the generation of large-scale continuous-variable (CV) hyperentanglement in three degrees of freedom (DOFs), including azimuthal and radial indexes of Laguerre-Gaussian (LG) modes and frequency. In our experiment, 216 pairs of hyperentangled modes are deterministically generated from the four-wave mixing process in an atomic vapor. Besides, we show that the entanglement between coherent LG superposition modes denoted by both azimuthal and radial quantum numbers can also be generated from this system. Such large-scale CV hyperentanglement in three DOFs presents an efficient scheme to significantly increase the information capacity of the CV system. Our results provide a new platform for studying CV quantum information and open the avenue for constructing high-capacity parallel and multiple-DOF CV quantum information protocols.show less
The temporal evolutions of electron density and plasma diameter of 1 kHz filament in air are investigated by utilizing a pump-probe longitudinal diffraction method. A model based on sca
The temporal evolutions of electron density and plasma diameter of 1 kHz filament in air are investigated by utilizing a pump-probe longitudinal diffraction method. A model based on scalar diffraction theory is proposed to extract the phase shift from the diffraction patterns. The hydrodynamic effect on plasma evolution at 1 kHz filament is included and analyzed. The measured initial peak electron density ~10^18 cm^-3 in our experimental conditions decays rapidly by nearly two orders of magnitude within 200 ps. Moreover, the plasma channel size rises from 90μm to 120μm as the delay time increases. The experimental observation is in agreement with numerical simulation results by solving the rate equations.show less
Snapshot spectral ghost imaging, which can acquire the dynamic spectral imaging information in the field of view, has attracted more attention in recent years. Studies have shown that o
Snapshot spectral ghost imaging, which can acquire the dynamic spectral imaging information in the field of view, has attracted more attention in recent years. Studies have shown that optimizing the fluctuation of light fields is essential to improve the sampling efficiency and the reconstruction quality of ghost imaging. However, the optimization of broadband light fields in snapshot spectral ghost imaging is challenging due to the dispersion of the modulation device. In the paper, by judiciously introducing a hybrid refraction/diffraction structure into the light field modulation, a snapshot spectral ghost imaging with broadband super-Rayleigh speckles was demonstrated. Simulation and experimental results verify that the contrast of speckles in a broad range of wavelengths has been significantly improved, and the imaging system has superior noise immunity.show less
We report on the generation and delivery of 10.2 PW peak power laser pulses, using the High Power Laser System (HPLS) at the Extreme Laser Infrastructure – Nuclear Physics (ELI-NP). In
We report on the generation and delivery of 10.2 PW peak power laser pulses, using the High Power Laser System (HPLS) at the Extreme Laser Infrastructure – Nuclear Physics (ELI-NP). In this work we demonstrate for the first time, to the best of our knowledge, the compression and propagation of full energy, full aperture, laser pulses that reach a power level of more than 10 PW.show less