On the Cover: Resolving and weighing the quantum orbits in strong-field tunneling ionization
Chinese Laser Press announces a new review journal Photonics Insights
On the Cover: Thermo-optically tunable spectral broadening in a nonlinear ultra-silicon-rich nitride Bragg grating
On the Cover: Optical beam splitting and asymmetric transmission in bi-layer metagratings
On the Cover: Deep compressed imaging via optimized pattern scanning

The image on the cover for Advanced Photonics Volume 3, Issue 3, depicts tunneling ionization of an atom, as induced by a strong laser pulse. The complex hologram in the photoelectron momentum spectrum, which encodes rich structural and dynamic information of the atom, originates from the interference of the photoelectrons tunneling at different times during the laser pulse. By introducing a weak second harmonic field, the contributions of the photoelectrons tunneling at different times are identified, a significant step toward imaging the ultrafast dynamics in atoms and molecules with the photoelectron spectroscopy of tunneling ionization.The image is based on original research by Jia Tan et al. presented in their paper “Resolving and weighing the quantum orbits in strong-field tunneling ionization,” Adv. Photon.3(3), 035001 (2021).

Photonics Insights will be a high-quality,peer-reviewed, Diamond Open Access journal. It will feature review articles which present the current status of a given topic, with background, research progress, conclusions, and possible future developments.

The image on the cover of Photonics Research Volume 9, Issue 4, demonstrates temperature tunable spectral broadening using a nonlinear ultra-silicon-rich nitride device consisting of a 3-mm-long cladding-modulated Bragg grating and a 7-mm-long nonlinear channel waveguide. Provided by Y. Cao et al., researchers from Singapore University of Technology and Design, Ecole Polytechnique Fédérale de Lausanne, Institute of Microelectronics, A*STAR and The University of Sydney, the image is based on the research presented in their article "Thermo-optically tunable spectral broadening in a nonlinear ultra-silicon-rich nitride Bragg grating", Photonics Research 9(4) 04000596, doi 10.1364/PRJ.411073.

The image on the cover of Chinese Optics Letters Volume 19, Issue 4, indicates that a new type of optical bi-layer metasurface system is designed and studied, which is based on subwavelength metal slit arrays with phase-gradient modulation, referred to as metagratings (MGs). Provided by Q. Shi et al., researchers from Soochow University, Nanjing University of Aeronautics and Astronautics and North University of China, the image is based on the research presented in their article "Optical beam splitting and asymmetric transmission in bi-layer metagratings", Chinese Optics Letters 19(4) 042602, doi 10.3788/COL202119.042602.

The image on the cover of Photonics Research Volume 9, Issue 3, presents a new imaging modality, deep compressed imaging via optimized-pattern scanning, which can significantly increase the acquisition speed for a single-detector-based imaging system. Provided by K. Zhang, J. Hu and W. Yang, researchers from University of California, the image is based on the research presented in their article "Deep compressed imaging via optimized pattern scanning", Photonics Research 9(3) 03000B57, doi 10.1364/PRJ.410556.

Editors' Picks
Complex Swift Hohenberg equation dissipative soliton fiber laser
Mode-locked lasers are the building blocks to generate ultrafast pulses which can then be used for many applications, including optical communication, metrology, spectroscopy, microscopy, material processing, as well as many applications in the healthcare industry. Mode-locked fiber lasers are especially popular for their compactness, efficiency, and beam quality compared to their solid-state counterparts. Apart from their practicality, the mode-locked fiber lasers are an interesting object for studies, as they represent dynamically rich nonlinear systems.
Photonics Research
  • Jul. 16, 2021
  • Vol. 9, Issue 6 (2021)
Editors' Picks
RF self-interference cancellation by using photonic technology
With the tremendous growth of modern wireless communications, crowded spectrum and waste of spectrum resources which limit the application of various wireless technologies, become the important issues, especially in beyond fifth generation (B5G) and sixth generation (6G) communications. Therefore, it is increasingly urgent to enhance spectrum utilization efficiency and to increase the wireless network capacity. Compared with the traditional frequency division duplex (FDD) and time division duplex (TDD), the in-band full-duplex (IBFD) technology transmitting and receiving signals simultaneously on the same frequency can double the spectrum utilization efficiency and data transmission rate, and has a great potential application in the new generation of mobile communications and satellite communications. However, in the process of IBFD communication, the transmitting antenna and the receiving antenna are generally on the same platform, the high-power signal sent from the transmitting antenna will interfere the low-power signal of interest (SOI) that is received by the receiving antenna, or even submerge it completely, which is called radio frequency (RF) self-interference. This kind of interference is at the same frequency as the SOI, so it is impossible to filter it out by a notch filter or to select the SOI by a narrow band pass filter. Therefore, RF self-interference is a key issue to be resolved for the application of IBFD technology.
Chinese Optics Letters
  • Jul. 13, 2021
  • Vol. 19, Issue 7 (2021)
Editors' Picks
All-optical sampling of few-cycle infrared pulses using tunneling in a solid
Intense, femtosecond laser pulses have for the last several decades been used for studies of ultrafast dynamics in atomic, molecular, and condensed matter systems. More recently, the development of techniques for nonlinear pulse compression to the single-optical-cycle limit and for stabilizing and controlling the carrier-envelope phase (the phase difference between the peak of the pulse envelope and the closest maximum of the oscillating electric field) has enabled the conversion of intense laser pulses into extreme ultraviolet attosecond pulses and ignited the field of attosecond science.
Photonics Research
  • Jul. 09, 2021
  • Vol. 9, Issue 6 (2021)
HPL Highlights
Multi-octave-spanning supercontinuum generation through high-energy laser filaments in YAG and ZnSe pumped by a 2.4 μm femtosecond Cr:ZnSe laser
The mid-infrared wavelength ranges from 2 to 15 μm is of great interest for many interesting applications such as remote sensing and free-space optical communications, but this spectral range has not been fully explored due to the lack of laser sources. In particular, the 3-8 μm range is called of the "molecular fingerprint" region because of the abundant absorption lines from almost most chemicals. These molecular fingerprints are very useful for chemical sensing in combination with broadband or tunable mid-infrared laser beams.
High Power Laser Science and Engineering
  • Jul. 08, 2021
  • Vol. 9, Issue 2 (2021)
Spotlight on Optics
First demonstration of an on-chip quadplexer for passive optical network systems
A new round of scientific and technological revolution is on-going around the world, Internet technology and smart terminals are constantly developing. Especially after the outbreak of COVID-19 in 2020, emerging businesses such as online education, online office, and online medical services have developed rapidly. The role of the Internet as an infrastructure to support the development of human society has become increasingly prominent.
Photonics Research
  • Jul. 01, 2021
  • Vol. 9, Issue 5 (2021)
Newest Articles
Discrepancy between transmission spectrum splitting and eigenvalue splitting: a reexamination on exceptional point-based sensors

In the study of exceptional point (EP)-based sensors, the concrete form of the output spectrum is often dismissed, and it is assumed that there is a corre

In the study of exceptional point (EP)-based sensors, the concrete form of the output spectrum is often dismissed, and it is assumed that there is a corresponding relation between the peaks/valleys in the transmission spectrum and the real parts of the eigenvalues of the system. We point out that this assumption does not always hold. An effect, which is mathematically similar to electromagnetically induced transparency (EIT), may result in a ‘pseudo spectrum splitting’ that does not correspond to the splitting between the eigenvalues. The effect shall be taken care of when designing an EP-based sensor since it may cause measurement error and misunderstanding such as recognization of the spectrum splitting as the eigenvalue splitting at the exceptional point. We also propose to intentionally utilize this ‘pseudo splitting’ to design a sensor, which does not work at an EP, that has an EP-like spectrum splitting.show less

  • Aug.02,2021
  • Photonics Research,Vol. 9, Issue 8
  • 08001645 (2021)
Epsilon-near-zero photonics: infinite potentials

With its unique and exclusive linear and nonlinear optical characteristics, epsilon-near-zero (ENZ) photonics has drawn a tremendous amount of attention i

With its unique and exclusive linear and nonlinear optical characteristics, epsilon-near-zero (ENZ) photonics has drawn a tremendous amount of attention in the recent decade in the fields of nanophotonics, nonlinear optics, plasmonics, light-matter interactions, material science, applied optical science, etc. The extraordinary optical properties, relatively high tuning flexibility, and CMOS compatibility of ENZ materials make them popular and competitive candidates for nanophotonic devices and on-chip integration in all-optical and electro-optical platforms. With exclusive features and high performance, ENZ photonics can play a big role in optical communications and optical data processing. In this review, we give a focused discussion on recent advances of the theoretical and experimental studies on ENZ photonics, especially in the regime of nonlinear ENZ nanophotonics and its applications. First, we overview the basics of the ENZ concepts, mechanisms, and nonlinear ENZ nanophotonics. Then the new advancements in theoretical and experimental optical physics are reviewed. For nanophotonic applications, the recent decades saw rapid developments in various kinds of different ENZ-based devices and systems, which are discussed and analyzed in detail. Finally, we give our perspectives on where future endeavors can be made.show less

  • Aug.02,2021
  • Photonics Research,Vol. 9, Issue 8
  • 08001616 (2021)
Bidirectional cascaded deep neural networks with a pretrained autoencoder for dielectric metasurfaces

Metasurfaces composed of meta-atoms provide promising platforms for manipulating amplitude, phase, and polarization of light. However, the traditional des

Metasurfaces composed of meta-atoms provide promising platforms for manipulating amplitude, phase, and polarization of light. However, the traditional design methods of metasurfaces are time consuming and laborious. Here, we propose a bidirectional cascaded deep neural network with a pretrained autoencoder for rapid design of dielectric metasurfaces in the range of 450 nm to 850 nm. The forward model realizes a prediction of amplitude and phase responses with a mean absolute error of 0.03. Meanwhile, the backward model can retrieve patterns of meta-atoms in an inverse-design manner. The availability of this model is demonstrated by database establishment, model evaluation, and generalization testing. Furthermore, we try to reveal the mechanism behind the model in a visualization way. The proposed approach is beneficial to reduce the cost of computation burden and improve nanophotonic design efficiency for solving electromagnetic on-demand design issues automatically.show less

  • Aug.02,2021
  • Photonics Research,Vol. 9, Issue 8
  • 08001607 (2021)
Formation of a three-dimensional bottle beam via an engineered microsphere

In this work, we propose a novel approach to produce three-dimensional (3D) optical trapping with sub-wavelength size through an engineered microsphere, u

In this work, we propose a novel approach to produce three-dimensional (3D) optical trapping with sub-wavelength size through an engineered microsphere, under linear polarization states of an incident light. The engineered microsphere is designed to contain the segmented regions of diffractive patterns and made by focused ion beam fabrication. We simulate and experimentally characterize the focus performance of the engineered microsphere. The emitted light field from the exit surface of the engineered microsphere forms a pair of axially arranged focused beams, and they are connected with a continuous optical field embracing a 3D optical null at the center, forming the so-called optical bottle beam. Experimental results and numerical simulation are in good agreement. Such micro-optics can be used for precise and localized optical trapping.show less

  • Aug.02,2021
  • Photonics Research,Vol. 9, Issue 8
  • 08001598 (2021)
Optics Physics Geography

In this paper, a high-power and high-efficient 4.3 µm mid-infrared (MIR) optical parametric oscillator (OPO) based on ZnGeP2 (ZGP) crystal is demonstrated. An acousto-optically (AO) Q-s

In this paper, a high-power and high-efficient 4.3 µm mid-infrared (MIR) optical parametric oscillator (OPO) based on ZnGeP2 (ZGP) crystal is demonstrated. An acousto-optically (AO) Q-switched Ho:YAG laser operating at 2.1 µm with a maximum average output power of 35 W and pulse width of 38 ns at a repetition rate of 15 kHz is established and employed as the pump source. A doubly-resonant OPO (DRO) is designed and realized with the total MIR output power of 13.27 W, including the signal and idler output power of 2.65 W@4.07 µm and 10.62 W @4.3 µm. The corresponding total optical-to-optical and slope efficiency are 37.9% and 67.1%, respectively. The shortest pulse width, the beam quality factor and the output power instability are measured to be 36 ns, Mx2=1.8, My2=2.0 and RMS<1.9%@8 hours, respectively. Our results pave a way for designing high-power and high-efficient 4-5 µm MIR laser sources.show less

  • Aug.02,2021
  • Chinese Optics Letters,Vol. 20, Issue 1
  • (2022)

A tunable multi-wavelength EDFL with precise wavelength interval control is reported theoretically and experimentally in this paper. It is made up of MZI filter and Sagnac filter, and s

A tunable multi-wavelength EDFL with precise wavelength interval control is reported theoretically and experimentally in this paper. It is made up of MZI filter and Sagnac filter, and supplemented by four-wave-mixing effect. Compared with other filters, the proposed MZI filter based on the fused taper technology can change the wavelength interval more flexibly. The experiment result shows that the wavelength tuning can be achieved and the tuning range can reach ~15nm. Moreover, the variation in the number of wavelengths are also realized. The maximum SMSR can reach 39dB. show less

  • Aug.02,2021
  • Chinese Optics Letters,Vol. 20, Issue 1
  • (2022)

A new unsaturated wind-chime model is proposed for calculating the formation time of the diffraction rings induced by spatial self-phase modulation (SSPM) in molybdenum disulfide suspen

A new unsaturated wind-chime model is proposed for calculating the formation time of the diffraction rings induced by spatial self-phase modulation (SSPM) in molybdenum disulfide suspension. To optimize the traditional wind-chime model, the concentration variable of 2D material was introduced. The results of the unsaturated wind-chime model match quite well with the SSPM experimental results of molybdenum disulfide. Based on this model, the shortest formation time of diffraction rings and their corresponding concentration and light intensity can be predicted using limited data. Theoretically, by increasing the viscosity coefficient of the solution, the response time of the diffraction ring, to reach the maximum value, can be significantly reduced. It has advanced significance in shortening the response time of photonic diodes. show less

  • Aug.02,2021
  • Chinese Optics Letters,Vol. 20, Issue 1
  • (2022)

In this paper, we use electromagnetic simulations to systematically investigate the influence of a thin dielectric layer on the local electric field and molecular spectroscopy in the pl

In this paper, we use electromagnetic simulations to systematically investigate the influence of a thin dielectric layer on the local electric field and molecular spectroscopy in the plasmonic junction. It is found that both the intensity and spatial confinement of the electric field and the molecular spectroscopy can be significantly enhanced by applying a dielectric layer with large dielectric constant. We also discuss the optimal dielectric layer thickness to obtain the largest quantum efficiency of a dipole emitter. These results may be instructive for further studies in molecular spectroscopy and optoelectronics in plasmonic junctions.show less

  • Aug.02,2021
  • Chinese Optics Letters,Vol. 19, Issue 12
  • (2021)
The image on the cover for Advanced Photonics Volume 3, Issue 3, depicts tunneling ionization of an atom, as induced by a strong laser pulse. The complex hologram in the photoelectron momentum spectrum, which encodes rich structural and dynamic information of the atom, originates from the interference of the photoelectrons tunneling at different times during the laser pulse. By introducing a weak second harmonic field, the contributions of the photoelectrons tunneling at different times are identified, a significant step toward imaging the ultrafast dynamics in atoms and molecules with the photoelectron spectroscopy of tunneling ionization.The image is based on original research by Jia Tan et al. presented in their paper “Resolving and weighing the quantum orbits in strong-field tunneling ionization,” Adv. Photon.3(3), 035001 (2021).
  • Journal
  • 20th Jul,2021
The image on the cover of Photonics Research Volume 9, Issue 4, demonstrates temperature tunable spectral broadening using a nonlinear ultra-silicon-rich nitride device consisting of a 3-mm-long cladding-modulated Bragg grating and a 7-mm-long nonlinear channel waveguide. Provided by Y. Cao et al., researchers from Singapore University of Technology and Design, Ecole Polytechnique F&eacute;d&eacute;rale de Lausanne, Institute of Microelectronics, A*STAR and The University of Sydney, the image is based on the research presented in their article "Thermo-optically tunable spectral broadening in a nonlinear ultra-silicon-rich nitride Bragg grating", Photonics Research 9(4) 04000596, doi 10.1364/PRJ.411073.
  • Journal
  • 27th Apr,2021