Contents
2023
Volume: 11 Issue 7
21 Article(s)
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Reviews
Lasers and Laser Optics
Open-ended exploration of ultrashort pulse lasers: an innovative design strategy for devices based on 2D materials
Qing Wu, Gang Zhao, Haibin Wu, and Meng Zhang
Ultrashort pulse lasers have vital significance in the field of ultrafast photonics. A saturable absorber (SA) as the core device to generate ultrashort pulses has innovative design strategies; the most interesting of which is the integration strategy based on 2D materials. This review presents recent advances in the optoelectronic properties of 2D materials and in the way the materials are prepared, characterized, and integrated into devices. We have done a comprehensive review of the optical properties of materials and material-based devices and their current development in the field of fiber lasers and solid-state lasers. Finally, we offer a look at future applications for 2D materials in ultrafast lasers and their prospects.Ultrashort pulse lasers have vital significance in the field of ultrafast photonics. A saturable absorber (SA) as the core device to generate ultrashort pulses has innovative design strategies; the most interesting of which is the integration strategy based on 2D materials. This review presents recent advances in the optoelectronic properties of 2D materials and in the way the materials are prepared, characterized, and integrated into devices. We have done a comprehensive review of the optical properties of materials and material-based devices and their current development in the field of fiber lasers and solid-state lasers. Finally, we offer a look at future applications for 2D materials in ultrafast lasers and their prospects..
Photonics Research
- Publication Date: Jun. 23, 2023
- Vol. 11, Issue 7, 1238 (2023)
Research Articles
Instrumentation and Measurements
1.5-m flat imaging system aligned and phased in real time | Spotlight on Optics
Zongliang Xie, Kaiyuan Yang, Yang Liu, Tianrong Xu... and Hu Yang|Show fewer author(s)
Flat optics has been considered promising for constructions of spaceborne imaging systems with apertures in excess of 10 m. Despite recent advances, there are long-existing challenges to perform in-phase stitching of multiple flat optical elements. Phasing the segmented planar instrument has remained at the proof of concept. Here, we achieve autonomous system-level cophasing of a 1.5-m stitching flat device, bridging the gap between the concept and engineering implementation. To do so, we propose a flat element stitching scheme, by manipulating the point spread function, which enables our demonstration of automatically bringing seven flat segments’ tip/tilt and piston errors within the tolerance. With phasing done, the 1.5-m system has become the largest phased planar instrument ever built in the world, to our knowledge. The first demonstration of phasing the large practical flat imaging system marks a significant step towards fielding a 10-m class one in space, also paving the way for ultrathin flat imaging in various remote applications.Flat optics has been considered promising for constructions of spaceborne imaging systems with apertures in excess of 10 m. Despite recent advances, there are long-existing challenges to perform in-phase stitching of multiple flat optical elements. Phasing the segmented planar instrument has remained at the proof of concept. Here, we achieve autonomous system-level cophasing of a 1.5-m stitching flat device, bridging the gap between the concept and engineering implementation. To do so, we propose a flat element stitching scheme, by manipulating the point spread function, which enables our demonstration of automatically bringing seven flat segments’ tip/tilt and piston errors within the tolerance. With phasing done, the 1.5-m system has become the largest phased planar instrument ever built in the world, to our knowledge. The first demonstration of phasing the large practical flat imaging system marks a significant step towards fielding a 10-m class one in space, also paving the way for ultrathin flat imaging in various remote applications..
Photonics Research
- Publication Date: Jun. 28, 2023
- Vol. 11, Issue 7, 1339 (2023)
Integrated Optics
Aluminum nitride waveguide beam splitters for integrated quantum photonic circuits
Hyeong-Soon Jang, Donghwa Lee, Hyungjun Heo, Yong-Su Kim... and Hojoong Jung|Show fewer author(s)
We demonstrate integrated photonic circuits for quantum devices using sputtered polycrystalline aluminum nitride (AlN) on insulator. On-chip AlN waveguide directional couplers, which are one of the most important components in quantum photonics, are fabricated and show the output power splitting ratios from 50:50 to 99:1. Polarization beam splitters with an extinction ratio of more than 10 dB are also realized from the AlN directional couplers. Using the fabricated AlN waveguide beam splitters, we observe Hong–Ou–Mandel interference with a visibility of 91.7%±5.66%.We demonstrate integrated photonic circuits for quantum devices using sputtered polycrystalline aluminum nitride (AlN) on insulator. On-chip AlN waveguide directional couplers, which are one of the most important components in quantum photonics, are fabricated and show the output power splitting ratios from 50:50 to 99:1. Polarization beam splitters with an extinction ratio of more than 10 dB are also realized from the AlN directional couplers. Using the fabricated AlN waveguide beam splitters, we observe Hong–Ou–Mandel interference with a visibility of
Photonics Research
- Publication Date: Jun. 19, 2023
- Vol. 11, Issue 7, 1196 (2023)
Nanophotonics and Photonic Crystals
Electrical manipulation of lightwaves in the uniaxially strained photonic honeycomb lattices under a pseudomagnetic field
Zhipeng Qi, Hao Sun, Guohua Hu, Chunyu Deng... and Yinping Cui|Show fewer author(s)
The realization of pseudomagnetic fields for lightwaves has attained great attention in the field of nanophotonics. Like real magnetic fields, Landau quantization could be induced by pseudomagnetic fields in the strain-engineered graphene. We demonstrated that pseudomagnetic fields can also be introduced to photonic crystals by exerting a linear parabolic deformation onto the honeycomb lattices, giving rise to degenerate energy states and flat plateaus in the photonic band structures. We successfully inspire the photonic snake modes corresponding to the helical state in the synthetic magnetic heterostructure by adopting a microdisk for the unidirectional coupling. By integrating heat electrodes, we can further electrically manipulate the photonic density of states for the uniaxially strained photonic crystal. This offers an unprecedented opportunity to obtain on-chip robust optical transports under the electrical tunable pseudomagnetic fields, opening the possibility to design Si-based functional topological photonic devices.The realization of pseudomagnetic fields for lightwaves has attained great attention in the field of nanophotonics. Like real magnetic fields, Landau quantization could be induced by pseudomagnetic fields in the strain-engineered graphene. We demonstrated that pseudomagnetic fields can also be introduced to photonic crystals by exerting a linear parabolic deformation onto the honeycomb lattices, giving rise to degenerate energy states and flat plateaus in the photonic band structures. We successfully inspire the photonic snake modes corresponding to the helical state in the synthetic magnetic heterostructure by adopting a microdisk for the unidirectional coupling. By integrating heat electrodes, we can further electrically manipulate the photonic density of states for the uniaxially strained photonic crystal. This offers an unprecedented opportunity to obtain on-chip robust optical transports under the electrical tunable pseudomagnetic fields, opening the possibility to design Si-based functional topological photonic devices..
Photonics Research
- Publication Date: Jun. 26, 2023
- Vol. 11, Issue 7, 1294 (2023)
Optical and Photonic Materials
Completely spin-decoupled geometric phase of a metasurface
Xinmin Fu, Jie Yang, Jiafu Wang, Yajuan Han... and Shaobo Qu|Show fewer author(s)
Metasurfaces have provided an unprecedented degree of freedom (DOF) in the manipulation of electromagnetic waves. A geometric phase can be readily obtained by rotating the meta-atoms of a metasurface. Nevertheless, such geomeshow moreMetasurfaces have provided an unprecedented degree of freedom (DOF) in the manipulation of electromagnetic waves. A geometric phase can be readily obtained by rotating the meta-atoms of a metasurface. Nevertheless, such geometric phases are usually spin-coupled, with the same magnitude but opposite signs for left- and right-handed circularly polarized (LCP and RCP) waves. To achieve independent control of LCP and RCP waves, it is crucial to obtain spin-decoupled geometric phases. In this paper, we propose to obtain completely spin-decoupled geometric phases by engineering the surface current paths on meta-atoms. Based on the rotational Doppler effect, the rotation manner is first analyzed, and it is found that the generation of a geometric phase lies in the rotation of the surface current paths on meta-atoms. Since the induced surface current paths under the LCP and RCP waves always start oppositely and are mirror-symmetrical with each other, it is natural that the geometric phases have the same magnitude and opposite signs when the meta-atoms are rotated. To obtain spin-decoupled geometric phases, the induced surface current under one spin should be rotated by one angle while the current under the other spin is rotated by a different angles. In this way, LCP and RCP waves can acquire different geometric phase changes. Proof-of-principle prototypes were designed, fabricated, and measured. Both the simulation and experiment results verify spin-decoupled geometric phases. This work provides a robust means to obtain a spin-dependent geometric phase and can be readily extended to higher frequency bands such as the terahertz, IR, and optical regimes..
Photonics Research
- Publication Date: Jun. 16, 2023
- Vol. 11, Issue 7, 1162 (2023)
Broadband omnidirectional visible spectral metamaterials
Jing Zhao, Xianfeng Wu, Di Cao, Mingchao Zhou... and Xiaopeng Zhao|Show fewer author(s)
Optical metamaterials offer the possibility of controlling the behavior of photons similarly to what has been done about electrons in semiconductors. However, most optical metamaterials are narrowband, and they achieve negatishow moreOptical metamaterials offer the possibility of controlling the behavior of photons similarly to what has been done about electrons in semiconductors. However, most optical metamaterials are narrowband, and they achieve negative refraction within a small window of incident angles, making them impractical for common visible light systems that operate effectively over a wide range of frequencies and directions. Considerable resistive loss at the resonant frequency of these metamaterials further prevents them from being deployed in the real world. Here, we develop a novel metamaterial randomly assembled by a list of narrowband, omnidirectional, and ultralow-loss meta-cluster systems using a bottom-up approach. Weak interactions among numerous meta-cluster sets greatly broaden the effective bandwidth of the overall structure, exhibiting frequency selectivity and spatial modulation when responding to white-light illumination. We observe negative refraction in the 490–730 nm band, and observe an inverse Doppler effect at green, yellow, and red frequencies, across most of the visible spectrum. Our method allows for low-cost fabrication of sizable broadband omnidirectional three-dimensional metamaterial samples, which opens the door to the rapid development of optical metamaterials, micro–nano assembly and preparation, tunable optical device engineering, etc..
Photonics Research
- Publication Date: Jun. 23, 2023
- Vol. 11, Issue 7, 1293 (2023)
Giant two-photon absorption of anatase TiO2 in Au/TiO2 core-shell nanoparticles
Lijie Wang, Tsz Him Chow, Malte Oppermann, Jianfang Wang, and Majed Chergui
We report on deep-to-near-UV transient absorption spectra of core-shell Au/SiO2 and Au/TiO2 nanoparticles (NPs) excited at the surface plasmon resonance of the Au core, and of UV-excited bare anatase TiO2 NPs. The bleaching of the first excitonic transition of anatase TiO2 at ∼3.8 eV is a signature of the presence of electrons/holes in the conduction band (CB)/valence band (VB) of the material. We find that while in bare anatase TiO2 NPs, two-photon excitation does not occur up to the highest used fluences (1.34 mJ/cm2), it takes place in the TiO2 shell at moderate fluences (0.18 mJ/cm2) in Au/TiO2 core-shell NPs, as a result of an enhancement due to the plasmon resonance. We estimate the enhancement factor to be of the order of ∼108–109. Remarkably, we observe that the bleach of the 3.8 eV band of TiO2 lives significantly longer than in bare TiO2, suggesting that the excess electrons/holes in the conduction/valence band are stored longer in this material.We report on deep-to-near-UV transient absorption spectra of core-shell
Photonics Research
- Publication Date: Jun. 28, 2023
- Vol. 11, Issue 7, 1303 (2023)
Optical Devices
Micropascal-sensitivity ultrasound sensors based on optical microcavities
Hao Yang, Xuening Cao, Zhi-Gang Hu, Yimeng Gao... and Bei-Bei Li|Show fewer author(s)
Whispering gallery mode (WGM) microcavities have been widely used for high-sensitivity ultrasound detection, owing to their optical and mechanical dual-resonance enhanced sensitivity. The ultrasound sensitivity of the cavity optomechanical system is fundamentally limited by thermal noise. In this work, we theoretically and experimentally investigate the thermal-noise-limited sensitivity of a WGM microdisk ultrasound sensor and optimize the sensitivity by varying the radius and a thickness of the microdisk, as well as using a trench structure around the disk. Utilizing a microdisk with a radius of 300 μm and thickness of 2 μm, we achieve a peak sensitivity of 1.18 μPa Hz-1/2 at 82.6 kHz. To the best of our knowledge, this represents the record sensitivity among cavity optomechanical ultrasound sensors. Such high sensitivity has the potential to improve the detection range of air-coupled ultrasound sensing technology.Whispering gallery mode (WGM) microcavities have been widely used for high-sensitivity ultrasound detection, owing to their optical and mechanical dual-resonance enhanced sensitivity. The ultrasound sensitivity of the cavity optomechanical system is fundamentally limited by thermal noise. In this work, we theoretically and experimentally investigate the thermal-noise-limited sensitivity of a WGM microdisk ultrasound sensor and optimize the sensitivity by varying the radius and a thickness of the microdisk, as well as using a trench structure around the disk. Utilizing a microdisk with a radius of 300 μm and thickness of 2 μm, we achieve a peak sensitivity of
Photonics Research
- Publication Date: Jun. 12, 2023
- Vol. 11, Issue 7, 1139 (2023)
High Q and sub-wavelength THz electric field confinement in ultrastrongly coupled THz resonators | Editors' Pick
Simon Messelot, Solen Coeymans, Jérôme Tignon, Sukhdeep Dhillon, and Juliette Mangeney
The control of light–matter coupling at the single electron level is currently a subject of growing interest for the development of novel quantum devices and for studies and applications of quantum electrodynamics. In the terahertz (THz) spectral range, this raises the particular and difficult challenge of building electromagnetic resonators that can conciliate low mode volume and high quality factor. Here, we report on hybrid THz cavities based on ultrastrong coupling between a Tamm cavity and an LC circuit metamaterial and show that they can combine high quality factors of up to Q=37 with a deep-subwavelength mode volume of V=3.2×10-4λ3. Our theoretical and experimental analysis of the coupled mode properties reveals that, in general, the ultrastrong coupling between a metamaterial and a Fabry–Perot cavity is an effective tool to almost completely suppress radiative losses and, thus, ultimately limit the total losses to the losses in the metallic layer. These Tamm cavity-LC metamaterial coupled resonators open a route toward the development of single photon THz emitters and detectors and to the exploration of ultrastrong THz light–matter coupling with a high degree of coherence in the few to single electron limit.The control of light–matter coupling at the single electron level is currently a subject of growing interest for the development of novel quantum devices and for studies and applications of quantum electrodynamics. In the terahertz (THz) spectral range, this raises the particular and difficult challenge of building electromagnetic resonators that can conciliate low mode volume and high quality factor. Here, we report on hybrid THz cavities based on ultrastrong coupling between a Tamm cavity and an LC circuit metamaterial and show that they can combine high quality factors of up to
Photonics Research
- Publication Date: Jun. 19, 2023
- Vol. 11, Issue 7, 1203 (2023)
Randomized whispering-gallery-mode microdisk laser arrays via cavity deformations for anti-counterfeiting labels
Wangqi Mao, Xinyu Gao, Bo Li, Yaqiang Zhang... and Long Zhang|Show fewer author(s)
Optical physical unclonable functions (PUFs) have emerged as a promising strategy for effective and unbreakable anti-counterfeiting. However, the unpredictable spatial distribution and broadband spectra of most optical PUFs cshow moreOptical physical unclonable functions (PUFs) have emerged as a promising strategy for effective and unbreakable anti-counterfeiting. However, the unpredictable spatial distribution and broadband spectra of most optical PUFs complicate efficient and accurate verification in practical anti-counterfeiting applications. Here, we propose an optical PUF-based anti-counterfeiting label from perovskite microlaser arrays, where randomness is introduced through vapor-induced microcavity deformation. The initial perovskite microdisk laser arrays with regular positions and uniform sizes are fabricated by femtosecond laser direct ablation. By introducing vapor fumigation to induce random deformations in each microlaser cavity, a laser array with completely uneven excitation thresholds and narrow-linewidth lasing signals is obtained. As a proof of concept, we demonstrated that the post-treated laser array can provide fixed-point and random lasing signals to facilitate information encoding. Furthermore, different emission states of the lasing signal can be achieved by altering the pump energy density to reflect higher capacity information. A threefold PUF (excited under three pump power densities) with a resolution of
Photonics Research
- Publication Date: Jun. 23, 2023
- Vol. 11, Issue 7, 1227 (2023)
Ultrawide-band optically transparent antidiffraction metamaterial absorber with a Thiessen-polygon metal-mesh shielding layer
Naitao Song, Qiao Sun, Su Xu, Dongzhi Shan... and Jingsong Gao|Show fewer author(s)
Transparent absorbers, with a functional integration of broadband electromagnetic shielding, microwave camouflage, and optical transparency, have attracted increasing attention in the past decades. Metal mesh, an artificial, show moreTransparent absorbers, with a functional integration of broadband electromagnetic shielding, microwave camouflage, and optical transparency, have attracted increasing attention in the past decades. Metal mesh, an artificial, optically transparent, conducting material composed of periodic metallic gratings, is the optimal choice for the microwave shielding layer of transparent absorbers because of its excellent compatibility between high transparency and low resistance. However, the micrometer-level periodicity of metallic grating concentrates the diffraction of light, which degrades the imaging quality of cameras and sensors in common. In this study, we report on a generalized Thiessen-polygon-randomization method that prevents the concentration of the diffraction of light in periodic metallic grating and demonstrate an ultrawide-band optically transparent diffraction-immune metamaterial absorber. The absorber is constructed with a multilayer indium-tin-oxide-based metasurface and a Thiessen-polygon-randomized metal-mesh reflector. The lossy metasurface provides multimode absorption, whereas the Thiessen-polygon randomization prevents the concentration of the diffraction of light. The practical sample achieves a 10 dB absorptivity and shielding effectiveness over a range of 8–26.5 GHz, and the optical transparency is also preserved over the entire visible and near-infrared regions. The point spread function and field of view are both improved by using the antidiffraction absorber. Our study paves the way for the application of optically transparent electromagnetic devices, display, and optoelectronic integration in a more practical stage..
Photonics Research
- Publication Date: Jun. 30, 2023
- Vol. 11, Issue 7, 1354 (2023)
Optoelectronics
All-in-one photoelectric logic gates by Dember photodetectors
Guoyang Cao, Changlei Wang, Yu Luo, and Xiaofeng Li
Photoelectric logic gates (PELGs) are the key component in integrated electronics due to their abilities of signal conversion and logic operations. However, traditional PELGs with fixed architectures can realize only very limited logic functions with relatively low on–off ratios. We present a self-driving polarized photodetector driven by the Dember effect, which yields ambipolar photocurrents through photonic modulation by a nested grating. The ambipolar response is realized by exciting the whispering-gallery mode and localized surface plasmon resonances, which leads to reverse spatial carrier generation and therefore the contrary photocurrent assisted by the Dember effect. We further design a full-functional PELG, which enables all five basic logic functions (“AND”, “OR”, “NOT”, “NAND”, and “NOR”) simultaneously in a single device by using one source and one photodetector only. Such an all-in-one PELG exhibits a strong robustness against structure size, incident wavelength, light power, and half-wave plate modulation, paving a way to the realization of ultracompact high-performance PELGs.Photoelectric logic gates (PELGs) are the key component in integrated electronics due to their abilities of signal conversion and logic operations. However, traditional PELGs with fixed architectures can realize only very limited logic functions with relatively low on–off ratios. We present a self-driving polarized photodetector driven by the Dember effect, which yields ambipolar photocurrents through photonic modulation by a nested grating. The ambipolar response is realized by exciting the whispering-gallery mode and localized surface plasmon resonances, which leads to reverse spatial carrier generation and therefore the contrary photocurrent assisted by the Dember effect. We further design a full-functional PELG, which enables all five basic logic functions (“AND”, “OR”, “NOT”, “NAND”, and “NOR”) simultaneously in a single device by using one source and one photodetector only. Such an all-in-one PELG exhibits a strong robustness against structure size, incident wavelength, light power, and half-wave plate modulation, paving a way to the realization of ultracompact high-performance PELGs..
Photonics Research
- Publication Date: Jun. 12, 2023
- Vol. 11, Issue 7, 1148 (2023)
AlGaN solar-blind phototransistor capable of directly detecting sub-fW signals: self-depletion and photorecovery of full-channel 2DEG enabled by a quasi-pseudomorphic structure
Jiabing Lu, Zesheng Lv, and Hao Jiang
Heterojunction field-effect phototransistors using two-dimensional electron gas (2DEG) for carrier transport have great potential in photodetection owing to its large internal gain. A vital factor in this device architecture show moreHeterojunction field-effect phototransistors using two-dimensional electron gas (2DEG) for carrier transport have great potential in photodetection owing to its large internal gain. A vital factor in this device architecture is the depletion and recovery of the 2DEG under darkness and illumination. This is usually achieved by adding an external gate, which not only increases the complexity of the fabrication and the electrical connection but also has difficulty ensuring low dark current (
Photonics Research
- Publication Date: Jun. 19, 2023
- Vol. 11, Issue 7, 1217 (2023)
Physical Optics
Steerable merging bound states in the continuum on a quasi-flatband of photonic crystal slabs without breaking symmetry
Xin Qi, Jiaju Wu, Feng Wu, Mina Ren... and Hong Chen|Show fewer author(s)
Optical resonators with high quality (Q) factors are paramount for the enhancement of light–matter interactions in engineered photonic structures, but their performance always suffers from the scattering loss caused by fabricshow moreOptical resonators with high quality (
Photonics Research
- Publication Date: Jun. 23, 2023
- Vol. 11, Issue 7, 1262 (2023)
Local characterization of the polarization state of 3D electromagnetic fields: an alternative approach
Rosario Martínez-Herrero, David Maluenda, Marcos Aviñoá, Artur Carnicer... and Ángel S. Sanz|Show fewer author(s)
A precise knowledge of the polarization state of light is crucial in technologies that involve the generation and application of structured light fields. The implementation of efficient methods to determine and characterize polarization states is mandatory; more importantly, these structured light fields must be at any spatial location at a low expense. Here, we introduce a new characterization method that relies on a rather convenient description of electric fields without neglecting their 3D nature. This method is particularly suitable for highly focused fields, which exhibit important polarization contributions along their propagation direction in the neighborhood of the focal region; i.e., the contributions out of the planes transverse to the optical axis, conventionally used to specify the polarization state of these fields. As shown, the method allows the extraction of information about the three field components at relatively low computational and experimental costs. Furthermore, it also allows characterization of the polarization state of a field in a rather simple manner. To check the feasibility and reliability of the method, we determined both analytically and experimentally the local polarization states for a series of benchmark input fields with it, finding excellent agreement between the theory and experiment.A precise knowledge of the polarization state of light is crucial in technologies that involve the generation and application of structured light fields. The implementation of efficient methods to determine and characterize polarization states is mandatory; more importantly, these structured light fields must be at any spatial location at a low expense. Here, we introduce a new characterization method that relies on a rather convenient description of electric fields without neglecting their 3D nature. This method is particularly suitable for highly focused fields, which exhibit important polarization contributions along their propagation direction in the neighborhood of the focal region; i.e., the contributions out of the planes transverse to the optical axis, conventionally used to specify the polarization state of these fields. As shown, the method allows the extraction of information about the three field components at relatively low computational and experimental costs. Furthermore, it also allows characterization of the polarization state of a field in a rather simple manner. To check the feasibility and reliability of the method, we determined both analytically and experimentally the local polarization states for a series of benchmark input fields with it, finding excellent agreement between the theory and experiment..
Photonics Research
- Publication Date: Jun. 28, 2023
- Vol. 11, Issue 7, 1326 (2023)
Quantum Optics
Towards optimum Franson interference recurrence in mode-locked singly-filtered biphoton frequency combs
Kai-Chi Chang, Xiang Cheng, Murat Can Sarihan, and Chee Wei Wong
Mode-locked biphoton frequency combs exhibit multiple discrete comblike temporal correlations from the Fourier transform of its phase-coherent frequency spectrum. Both temporal correlation and Franson interferometry are valuashow moreMode-locked biphoton frequency combs exhibit multiple discrete comblike temporal correlations from the Fourier transform of its phase-coherent frequency spectrum. Both temporal correlation and Franson interferometry are valuable tools for analyzing the joint properties of biphoton frequency combs, and the latter has proven to be essential for testing the fundamental quantum nature, the time-energy entanglement distribution, and the large-alphabet quantum key distributions. However, the Franson recurrence interference visibility in biphoton frequency combs unavoidably experiences a falloff that deteriorates the quality of time-energy entanglement and channel capacity for longer cavity round trips. In this paper, we provide a new method to address this problem towards optimum Franson interference recurrence. We first observe mode-locked temporal oscillations in a 5.03 GHz free-spectral range singly filtered biphoton frequency comb using only commercial detectors. Then, we observe similar falloff trend of time-energy entanglement in 15.15 GHz and 5.03 GHz free-spectral range singly filtered biphoton frequency combs, whereas, the optimum central time-bin accidental-subtracted visibility over 97% for both cavities. Here, we find that by increasing the cavity finesse
Photonics Research
- Publication Date: Jun. 16, 2023
- Vol. 11, Issue 7, 1175 (2023)
Photonic-reconfigurable entanglement distribution network based on silicon quantum photonics | Editors' Pick
Dongning Liu, Jingyuan Liu, Xiaosong Ren, Xue Feng... and Wei Zhang|Show fewer author(s)
The entanglement distribution network connects remote users by sharing entanglement resources, which is essential for realizing quantum internet. We propose a photonic-reconfigurable entanglement distribution network (PR-EDN) based on a silicon quantum photonic chip. The entanglement resources are generated by a quantum light source array based on spontaneous four-wave mixing in silicon waveguides and distributed to different users through time-reversed Hong–Ou–Mandel interference by on-chip Mach–Zehnder interferometers with thermo-optic phase shifters (TOPSs). A chip sample is designed and fabricated, supporting a PR-EDN with 3 subnets and 24 users. The network topology of the PR-EDN could be reconfigured in three network states by controlling the quantum interference through the TOPSs, which is demonstrated experimentally. Furthermore, a reconfigurable entanglement-based quantum key distribution network is realized as an application of the PR-EDN. The reconfigurable network topology makes the PR-EDN suitable for future quantum networks requiring complicated network control and management. Moreover, it is also shown that silicon quantum photonic chips have great potential for large-scale PR-EDN, thanks to their capacities for generating and manipulating plenty of entanglement resources.The entanglement distribution network connects remote users by sharing entanglement resources, which is essential for realizing quantum internet. We propose a photonic-reconfigurable entanglement distribution network (PR-EDN) based on a silicon quantum photonic chip. The entanglement resources are generated by a quantum light source array based on spontaneous four-wave mixing in silicon waveguides and distributed to different users through time-reversed Hong–Ou–Mandel interference by on-chip Mach–Zehnder interferometers with thermo-optic phase shifters (TOPSs). A chip sample is designed and fabricated, supporting a PR-EDN with 3 subnets and 24 users. The network topology of the PR-EDN could be reconfigured in three network states by controlling the quantum interference through the TOPSs, which is demonstrated experimentally. Furthermore, a reconfigurable entanglement-based quantum key distribution network is realized as an application of the PR-EDN. The reconfigurable network topology makes the PR-EDN suitable for future quantum networks requiring complicated network control and management. Moreover, it is also shown that silicon quantum photonic chips have great potential for large-scale PR-EDN, thanks to their capacities for generating and manipulating plenty of entanglement resources..
Photonics Research
- Publication Date: Jun. 28, 2023
- Vol. 11, Issue 7, 1314 (2023)
Silicon Photonics
High-efficiency reflector-less dual-level silicon photonic grating coupler
Valerio Vitali, Thalía Domínguez Bucio, Cosimo Lacava, Riccardo Marchetti... and Periklis Petropoulos|Show fewer author(s)
We present the design and experimentally demonstrate a dual-level grating coupler with subdecibel efficiency for a 220 nm thick silicon photonics waveguide which was fabricated starting from a 340 nm silicon-on-insulator wafer. The proposed device consists of two grating levels designed with two different linear apodizations, with opposite chirping signs, and whose period is varied for each scattering unit. A coupling efficiency of -0.8 dB at 1550 nm is experimentally demonstrated, which represents the highest efficiency ever reported in the telecommunications C-band in a single-layer silicon grating structure without the use of any backreflector or index-matching material between the fiber and the grating.We present the design and experimentally demonstrate a dual-level grating coupler with subdecibel efficiency for a 220 nm thick silicon photonics waveguide which was fabricated starting from a 340 nm silicon-on-insulator wafer. The proposed device consists of two grating levels designed with two different linear apodizations, with opposite chirping signs, and whose period is varied for each scattering unit. A coupling efficiency of
Photonics Research
- Publication Date: Jun. 26, 2023
- Vol. 11, Issue 7, 1275 (2023)
Spectroscopy
Dual-comb spectroscopy from the ultraviolet to mid-infrared region based on high-order harmonic generation
Yuanfeng Di, Zhong Zuo, Daowang Peng, Daping Luo... and Wenxue Li|Show fewer author(s)
Dual-comb spectroscopy (DCS) has revolutionized numerous spectroscopic applications due to its high spectral resolution and fast measurement speed. Substantial efforts have been made to obtain a coherent dual-comb source at vshow moreDual-comb spectroscopy (DCS) has revolutionized numerous spectroscopic applications due to its high spectral resolution and fast measurement speed. Substantial efforts have been made to obtain a coherent dual-comb source at various spectral regions through nonlinear frequency conversion, where the preservation of coherence has become a problem of great importance. In this study, we report the generation of coherent dual-comb sources covering from the ultraviolet to mid-infrared region based on high-order harmonic generation. Driven by high-repetition-rate femtosecond mid-infrared dual-comb pump pulses, up to ninth-order harmonic was generated from the ultraviolet to mid-infrared region using an aperiodically poled lithium niobate waveguide. To investigate the coherence property of the high-order harmonic generation, DCS was performed at every generated spectral region from 450 to 3600 nm. The measured dual-comb spectra with distinctive tooth-resolved structures show the well-preserved coherence without apparent degradation after the cascaded quadratic nonlinear processes. The subsequent methane absorption spectroscopy at multiple spectral regions of different harmonics was carried out to characterize the spectroscopic capability of the system. These results demonstrate the potential of our scheme to generate compact and coherent broadband optical frequency combs for simultaneous multi-target detections..
Photonics Research
- Publication Date: Jun. 30, 2023
- Vol. 11, Issue 7, 1373 (2023)
Surface Optics and Plasmonics
Switchable chiral mirror based on PIN diodes
Zhibiao Zhu, Zhe Qin, He Wang, Lixin Jiang... and Shaobo Qu|Show fewer author(s)
Chiral mirrors can produce spin selective absorption for left-handed circularly polarized (LCP) or right-handed circularly polarized (RCP) waves. However, the previously proposed chiral mirror only absorbs the designated circularly polarized (CP) wave in the microwave frequency band, lacking versatility in practical applications. Here, we propose a switchable chiral mirror based on a pair of PIN diodes. The switchable chiral mirror has four working states, switching from the handedness-preserving mirror to the LCP mirror, RCP mirror, and perfect absorber. The basis of these advances is to change the chirality of two-dimensional (2D) chiral metamaterials and the circular conversion dichroism related to it, which is the first report in the microwave frequency band. Surface current distributions shed light on how switchable chiral mirrors work by handedness-selective excitation of reflective and absorbing electric dipole modes. Energy loss distributions verify the working mechanism. The thickness of the switchable chiral mirror is one-tenth of the working wavelength, which is suitable for integrated manufacturing. The measurement results are in good agreement with the simulation results.Chiral mirrors can produce spin selective absorption for left-handed circularly polarized (LCP) or right-handed circularly polarized (RCP) waves. However, the previously proposed chiral mirror only absorbs the designated circularly polarized (CP) wave in the microwave frequency band, lacking versatility in practical applications. Here, we propose a switchable chiral mirror based on a pair of PIN diodes. The switchable chiral mirror has four working states, switching from the handedness-preserving mirror to the LCP mirror, RCP mirror, and perfect absorber. The basis of these advances is to change the chirality of two-dimensional (2D) chiral metamaterials and the circular conversion dichroism related to it, which is the first report in the microwave frequency band. Surface current distributions shed light on how switchable chiral mirrors work by handedness-selective excitation of reflective and absorbing electric dipole modes. Energy loss distributions verify the working mechanism. The thickness of the switchable chiral mirror is one-tenth of the working wavelength, which is suitable for integrated manufacturing. The measurement results are in good agreement with the simulation results..
Photonics Research
- Publication Date: Jun. 16, 2023
- Vol. 11, Issue 7, 1154 (2023)
BICs-enhanced active terahertz wavefront modulator enabled by laser-cut graphene ribbons | On the Cover
Jianzhou Huang, Bin Hu, Guocui Wang, Zongyuan Wang... and Yan Zhang|Show fewer author(s)
Graphene-based terahertz (THz) metasurfaces combined with metallic antennas have the advantages of ultra-small thickness, electrical tunability, and fast tuning speed. However, their tuning ability is limited by non-independently tunable pixels and low modulation depth due to the ultra-small thickness of graphene. Here, we demonstrate a reconfigurable THz phase modulator with 5×5 independently tunable units enabled by switching the voltages applied on 10 graphene ribbons prepared by laser cutting. In addition, by introducing quasi-bound states in the continuum resonance through a designed double C-shaped antenna, the efficiency of the device is enhanced by 2.7–3.6 times under different graphene chemical potentials. Experimental results demonstrate that a focus can be formed, and the focal length is changed from 14.3 mm to 22.6 mm. This work provides potential for compact THz spatial light modulators that may be applied in THz communication, detection, and imaging.Graphene-based terahertz (THz) metasurfaces combined with metallic antennas have the advantages of ultra-small thickness, electrical tunability, and fast tuning speed. However, their tuning ability is limited by non-independently tunable pixels and low modulation depth due to the ultra-small thickness of graphene. Here, we demonstrate a reconfigurable THz phase modulator with
Photonics Research
- Publication Date: Jun. 19, 2023
- Vol. 11, Issue 7, 1185 (2023)
About the Cover
The graphene-based pixelated and ultra-thin metasurface enables high-speed independent pixel terahertz wavefront reconstruction. This work provides a new potential for compact THz spatial light modulators which may be applied in THz communication, detection, and imaging. See Jianzhou Huang et al., pp. 1185-1195.
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