Researching | Free Literatures in Optics and Photonics

On the Cover: Topological photonic states in artificial microstructures [Invited]

On the Cover: Extremely regular periodic surface structures in a large area efficiently induced on silicon by temporally shaped femtosecond laser

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: Topological photonic states in artificial microstructures [Invited]

The image on the cover for Chinese Optics Letters Volume 19, Issue 5, indicates that Topological photonics provides a new opportunity for the examination of novel topological properties of matter, in which the energy band theory and ideas in topology are utilized to manipulate the propagation of photons.The image is based on original research by Hui Liu et al. presented in their paper "Topological photonic states in artificial microstructures [Invited]", Chinese Optics Letters 19 (5), 052602 (2021).

On the Cover: Extremely regular periodic surface structures in a large area efficiently induced on silicon by temporally shaped femtosecond laser

The image on the cover for Photonics Research Volume 9, Issue 5, indicates that Femtosecond laser-induced periodic surface structures (LIPSS) have several applications in surface structuring and functionalization. Three major challenges exist in the fabrication of regular and uniform LIPSS: enhancing the periodic energy deposition, reducing the residual heat, and avoiding the deposited debris. The image is based on original research by Yuchan Zhang et al. presented in their paper "Extremely regular periodic surface structures in a large area efficiently induced on silicon by temporally shaped femtosecond laser", Photonics Research 9 (5), 05000839 (2021).

On the Cover: Resolving and weighing the quantum orbits in strong-field tunneling ionization

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).

Chinese Laser Press announces a new review journal Photonics Insights

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.

On the Cover: Thermo-optically tunable spectral broadening in a nonlinear ultra-silicon-rich nitride Bragg grating

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.

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Editors' Picks

Higher-order topological phases in tunable C3 symmetric photonic crystals

Topological phases and phase transition have been extensively studied in electronic, photonic, and acoustic systems in the past decades. Recently, a new class of topological insulators, called higher-order topological insulators (HOTIs) that are characterized by higher-order bulk-boundary correspondence, were discovered.

Photonics Research

Sep. 22, 2021
Vol. 9, Issue 9 (2021)

COL Highlights

SNR improvement of 8.2 dB in a self-mixing laser diode interferometer by using the difference signal at the output mirrors

The self-mixing interferometer (SMI) is a sort of optical radar capable of detecting extremely weak optical returns from a remotely located target and measuring the amplitude and phase of it. Different from the traditional radar based on launching a pulse to the target, the SMI uses a continuous coherent beam and operates as a coherent detector. Thanks to this feature, SMI has an unparalleled sensitivity to very small returns (down to 10-8 of the launched power) and can measure the phase – that is the optical pathlength down the target and back-with resolution of milliradian, that translates into optical pathlength attaining fractions of nanometers.

Chinese Optics Letters

Sep. 16, 2021
Vol. 19, Issue 9 (2021)

Spotlight on Optics

Bandpass-filter-integrated multiwavelength achromatic metalens

Chromatic aberration of an optical lens arises from the variation of focal length with respect to the wavelength of light caused by the material dispersion, which is a common phenomenon in white light imaging. This aberration will lead to the color blurring and severely degrade the image quality.

Photonics Research

Sep. 15, 2021
Vol. 9, Issue 7 (2021)

Editors' Picks

In-plane excitation of a topological nanophotonic corner state at telecom wavelengths in a cross-coupled cavity

Optical cavity, as one of the important elements of nanophotonics, is widely used in many fields, such as optical communications, sensing, quantum optics, and gravitational-wave detection. These applications have driven the development of high-performance cavity and cavity-based integrated devices, which is highly relevant to the control capability of cavity modes.

Photonics Research

Sep. 10, 2021
Vol. 9, Issue 8 (2021)

AP Highlights

Enhanced generation of nondegenerate photon pairs in nonlinear metasurfaces

Quantum nanophotonics is an active research field with emerging applications that range from quantum computing to imaging and telecommunications. This has motivated scientists and engineers to develop sources for entangled photons that can be integrated into nano-scale photonic circuits. Practical application of nanoscale devices requires a high photon-pair generation rate, room-temperature operation, and entangled photons emitted at telecommunications wavelengths in a directional manner.

Advanced Photonics

Sep. 08, 2021
Vol. 3, Issue 5 (2021)

Newest Articles

Miniature optical force levitation system

Optical levitation technology is a new levitation technology for trapping micro/nano-particles. By taking advantage of the mechanical effect of light, it

Optical levitation technology is a new levitation technology for trapping micro/nano-particles. By taking advantage of the mechanical effect of light, it has the characteristics of non-contact and high sensitivity. However, the traditional optical levitation system is large in volume, complex in adjustment, and greatly affected by the external environment. Herein, a miniature optical levitation system based on a laser diode, miniature lenses, and a micro-electro-mechanical system (MEMS) particles cavity is proposed. First, we analyze the output spot characteristics of the laser diode. Being compared the characteristics of different kinds of laser diodes, the type, wavelength, and power of diodes in the levitation system are determined. Then, the micro-particles cavity is fabricated based on the MEMS process. The MEMS process is widely used in the manufacturing of micro-electronic devices because of its advantages of small size, high precision, and easy mass production. The particle cavity processed in this way can not only ensure the advantage of small volume, but also possesses high processing repeatability. The volume of the entire package including the light source, focusing lenses, and MEMS cavity is just $Φ 10 mm \times 33 mm$ , which is the smallest optical levitation system reported, to the best of our knowledge. After the entire levitation system is designed and set up, one silica particle of 10 µm diameter is stably trapped in the atmospheric environment. Finally, the micro-displacement and vibration signal are detected by a four-quadrant photoelectric detector to evaluate the stiffness of the optical levitation system.show less

Sep.23，2021

Chinese Optics Letters,Vol. 20, Issue 1
013801 (2022)

Electro-optically tunable microdisk laser on Er³⁺-doped lithium niobate thin film

We report an electro-optically (EO) tunable microdisk laser fabricated on the erbium (Er3+)-doped lithium niobate on insulator (LNOI) substrate. By applyi

We report an electro-optically (EO) tunable microdisk laser fabricated on the erbium ( ${Er}^{3 +}$ )-doped lithium niobate on insulator (LNOI) substrate. By applying a variable voltage on a pair of integrated chromium (Cr) microelectrodes fabricated near the LNOI microdisk, electro-optic modulation with an effective resonance-frequency tuning rate of 2.6 GHz/100 V has been achieved. This gives rise to a tuning range of 45 pm when the electric voltage is varied between $- 200 V$ and 200 V.show less

Sep.23，2021

Chinese Optics Letters,Vol. 20, Issue 1
011303 (2022)

Efficient silicon integrated four-mode edge coupler for few-mode fiber coupling

Here, we designed a broadband, low loss, compact, and fabrication-tolerant silicon-based four-mode edge coupler, composed of a 1×3 adiabatic mode-evo

Here, we designed a broadband, low loss, compact, and fabrication-tolerant silicon-based four-mode edge coupler, composed of a $1 \times 3$ adiabatic mode-evolution counter-taper splitter and a triple-tip inverse taper. Based on mode conversion and power splitting, the proposed structure can simultaneously realize efficient mode coupling from ${TE}_{0}$ , ${TM}_{0}$ , ${TE}_{1}$ , and ${TM}_{1}$ modes of multimode silicon waveguides to linearly polarized (LP), ${LP}_{01, x}$ , ${LP}_{01, y}$ , ${LP}_{11 a, x}$ , and ${LP}_{11 a, y}$ , modes in the few-mode fiber. To the best of our knowledge, we proposed the first scheme of four LP modes coupling, which is fully compatible with standard fabrication process. The 3D finite-difference time-domain simulation results show that the on-chip conversion losses of the four modes remain lower than 0.62 dB over the 200 nm wavelength range, and total coupling losses are 4.1 dB, 5.1 dB, 2.1 dB, and 2.9 dB for ${TE}_{0} -to- {LP}_{01, x}$ , ${TM}_{0} -to- {LP}_{01, y}$ , ${TE}_{1} -to- {LP}_{11 a, x}$ , and ${TM}_{1} -to- {LP}_{11 a, y}$ , respectively. Good fabrication tolerance and relaxed critical dimensions make the four-mode edge coupler compatible with standard fabrication process of commercial silicon photonic foundries.show less

Sep.23，2021

Chinese Optics Letters,Vol. 20, Issue 1
011302 (2022)

Holographic visualization of volume data based on adjustable ray to optical-wave conversion

A holographic visualization of volume data based on adjustable ray to optical-wave conversion is presented. Computer-generated holograms are generated by

A holographic visualization of volume data based on adjustable ray to optical-wave conversion is presented. Computer-generated holograms are generated by emitting multiple rays to sample the volumetric field. Equal interval sampling, object light wave adjustment, and information composition are sequentially performed during the march of rays. The program is accelerated in parallel to reduce the total time, and the reconstructions are dynamically adjusted to express different parts of an object. Optical experiments verify that the proposed method can holographically reconstruct the surface and interior information of objects.show less

Sep.23，2021

Chinese Optics Letters,Vol. 20, Issue 1
010501 (2022)

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Physics

Geography

Early Posting

Power-scalable sub-100-fs Tm laser at 2.08 μm

We report on a power-scalable sub-100-fs laser in the 2-μm spectral range using a Tm3+-doped “mixed” (Lu,Sc)2O3 sesquioxide ceramic as an active medium. Pulses as short as 58 fs at 2076

We report on a power-scalable sub-100-fs laser in the 2-μm spectral range using a Tm3+-doped “mixed” (Lu,Sc)2O3 sesquioxide ceramic as an active medium. Pulses as short as 58 fs at 2076 nm with an average output power of 114 mW at a pulse repetition rate of ~ 82.9 MHz are generated by employing single-walled carbon nanotubes as a saturable absorber. Higher average power of 350 mW at 2075 nm is obtained at the expense of the pulse duration (65 fs). A maximum average power of 486 mW is achieved for a pulse duration of 98 fs and an optical conversion efficiency of 22.3%, representing the highest value ever reported from sub-100-fs mode-locked Tm-lasers.show less

Sep.23，2021

High Power Laser Science and Engineering

Lithium niobate microring with ultra-high Q factor above 10⁸

Abstract: We demonstrate integrated lithium niobate (LN) microring resonators with Q factors close to the intrinsic material absorption limit of LN. The microrings are fabricated on pri

Abstract: We demonstrate integrated lithium niobate (LN) microring resonators with Q factors close to the intrinsic material absorption limit of LN. The microrings are fabricated on pristine LN thin-film wafer thinned from LN bulk via chemo-mechanical etching without ion slicing and ion etching. A record-high Q factor up to 10<sup>8</sup> at the wavelength of 1550 nm is achieved because of the ultra-smooth interface of the microrings and the absence of ion-induced lattice damage, indicating an ultra-low waveguide propagation loss of ∼0.0034 dB/cm. The ultra-high Q microrings will pave the way for integrated quantum light source, frequency comb generation, and nonlinear optical processes.show less

Sep.23，2021

Chinese Optics Letters,Vol. 20, Issue 1
(2022)

Ultrasensitive liquid level sensor based on slice-shaped composite long period fiber grating

In this paper, a novel liquid level sensor with ultra-high sensitivity is proposed. The proposed sensor is configured by slice-shaped composite long period fiber grating (SSC-LPFG). SSC

In this paper, a novel liquid level sensor with ultra-high sensitivity is proposed. The proposed sensor is configured by slice-shaped composite long period fiber grating (SSC-LPFG). SSC-LPFG is prepared by polishing on two opposite sides of composite multimode-single-mode-multimode (C-MSM) fiber structure using CO2 laser. The method improves the sensitivity of the sensor to external environment. Based on the simulation calculation, a liquid level sensor with a length of 3 mm is designed. The experimental transmission spectrum agrees well with the simulation result. The experimental results show that the sensitivity reaches 7080 pm/mm in the liquid level range of 0-1400 μm in water. The temperature sensitivity is 24.52 pm/°C in the range of 20-90 °C. Due to the ultra-high sensitivity, good linearity, and compact structure, the SSC-LPFG has the potential application in the field of high precision liquid level measurement.show less