Author Affiliations
Abstract
1 State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
2 State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing 100084, China
3 e-mail: zhennan_tian@jlu.edu.cn
4 e-mail: hbsun@tsinghua.edu.cn
Femtosecond laser direct writing (FsLDW) three-dimensional (3D) photonic integrated circuits (PICs) can realize arbitrary arrangement of waveguide arrays and coupling devices. Thus, they are capable of directly constructing arbitrary Hamiltonians and performing specific computing tasks crucial in quantum simulation and computation. However, the propagation constant is limited to a narrow range in single-mode waveguides by solely changing the processing parameters, which greatly hinders the design of FsLDW PICs. This study proposes a composite waveguide (CWG) method to increase the range of , where a new single-mode composite waveguide comprises two adjacent circular waveguides. As a result, the photon propagation can be controlled and the variation range of can be efficiently enlarged by approximately two times (). With the CWG method, we successfully realize the most compact FsLDW directional couplers with a 9 μm pitch in a straight-line form and achieve the reconstruction of the Hamiltonian of a Hermitian array. Thus, the study represents a step further toward the fine control of the coupling between waveguides and compact integration of FsLDW PICs.
Photonics Research
2023, 11(5): 829
Author Affiliations
Abstract
Carnivorous plants, for instance, Dionaea muscipula and Nepenthes pitcher plant, inspired the innovation of advanced stimuli-responsive actuators and lubricant-infused slippery surfaces, respectively. However, hybrid bionic devices that combine the active and passive prey trapping capabilities of the two kinds of carnivorous plants remain a challenge. Herein, we report a moisture responsive shape-morphing slippery surface that enables both moisture responsive shape-morphing and oil-lubricated water repellency for simultaneous active- and passive-droplet manipulation. The moisture deformable slippery surface is prepared by creating biomimetic microstructures on graphene oxide (GO) membrane via femtosecond laser direct writing and subsequent lubricating with a thin layer of oil on the laser structured reduced GO (LRGO) surface. The integration of a lubricant-infused slippery surface with an LRGO/GO bilayer actuator endows the actuator with droplet sliding ability and promotes the moisture deformation performance due to oil-enhanced water repellency of the inert layer (LRGO). Based on the shape-morphing slippery surface, we prepared a series of proof-of-concept actuators, including a moisture-response Dionaea muscipula actuator, a smart frog tongue, and a smart flower, demonstrating their versatility for active/passive trapping, droplet manipulation, and sensing.Carnivorous plants, for instance, Dionaea muscipula and Nepenthes pitcher plant, inspired the innovation of advanced stimuli-responsive actuators and lubricant-infused slippery surfaces, respectively. However, hybrid bionic devices that combine the active and passive prey trapping capabilities of the two kinds of carnivorous plants remain a challenge. Herein, we report a moisture responsive shape-morphing slippery surface that enables both moisture responsive shape-morphing and oil-lubricated water repellency for simultaneous active- and passive-droplet manipulation. The moisture deformable slippery surface is prepared by creating biomimetic microstructures on graphene oxide (GO) membrane via femtosecond laser direct writing and subsequent lubricating with a thin layer of oil on the laser structured reduced GO (LRGO) surface. The integration of a lubricant-infused slippery surface with an LRGO/GO bilayer actuator endows the actuator with droplet sliding ability and promotes the moisture deformation performance due to oil-enhanced water repellency of the inert layer (LRGO). Based on the shape-morphing slippery surface, we prepared a series of proof-of-concept actuators, including a moisture-response Dionaea muscipula actuator, a smart frog tongue, and a smart flower, demonstrating their versatility for active/passive trapping, droplet manipulation, and sensing.
femtosecond laser fabrication graphene oxide moisture responsive actuators slippery surface bionic devices Opto-Electronic Advances
2023, 6(1): 210163
Author Affiliations
Abstract
Because of the strong Coulomb interaction and quantum confinement effect, 2-dimensional transition metal dichalcogenides possess a stable excitonic population. To realize excitonic device applications, such as excitonic circuits, switches, and transistors, it is of paramount importance for understanding the optical properties of transition metal dichalcogenides. Furthermore, the strong quantum confinement in 2-dimensional space introduces exotic properties, such as enhanced phonon bottlenecking effect, many-body interaction of excitons, and ultrafast nonequilibrium exciton–exciton annihilation. Exciton diffusion is the primary energy dissipation process and a working horse in excitonic devices. In this work, we investigated time-resolved exciton propagation in monolayer semiconductors of WSe2, MoWSe2, and MoSe2, with a home-built femtosecond pump-probe microscope. We observed ultrafast exciton expansion behavior with an equivalent diffusivity of up to 502 cm2 s-1 at the initial delay time, followed by a slow linear diffusive regime (20.9 cm2 s-1) in the monolayer WSe2. The fast expansion behavior is attributed to energetic carrier-dominated superdiffusive behavior. We found that in the monolayers MoWSe2 and MoSe2, the energetic carrier-induced exciton expansion is much more effective, with diffusivity up to 668 and 2295 cm2 s-1, respectively. However, the “cold” exciton transport is trap limited in MoWSe2 and MoSe2, leading to negative diffusion behavior at later time. Our findings are helpful to better understand the ultrafast nonlinear diffusive behavior in strongly quantum-confined systems. It may be harnessed to break the limit of conventional slow diffusion of excitons for advancing more efficient and ultrafast optoelectronic devices.
Ultrafast Science
2022, 2(1): 0002
Author Affiliations
Abstract
1 State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
2 State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
3 State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Haidian, Beijing 100084, China
Strong light-matter interactions in two-dimensional transition metal dichalcogenides (TMDCs) with robust spin-valley degrees of freedom open up the prospect of valleytronic devices. A thorough understanding on the dynamics of the valley polarizations in the strong coupling regime is urgently required. Here, multiple polarized TMDCs-SPPs hybrid systems were constructed by combining monolayer WS2 flakes to linear, circular, and spiral Ag gratings, resulting in linear and circular polarized modulation on the coherent hybrid states, respectively. Particularly, valley polaritons can be tailored asymmetrically by chiral strong coupling regime. Furthermore, the dynamics of the polarized polaritons were directly analyzed by transient absorption (TA) measurement. Both of the linear and circular polarization difference in the TA spectra can be retained for a remarkable long time, leading to a polarized PL even at room temperature. More importantly, in the chiral strong coupled WS2-spiral Ag grating devices, the mechanism of the asymmetrical valley-polarized PL (p σ+ = 14.9% and p σ- = 10.8%) is proved by the opposite valley polarization dynamics in the circularly polarized TA spectra. The multiple polarization modulation in monolayer TMDCs-SPPs strong coupling devices could provide a viable route toward multiple polarization polaritonic devices.
Author Affiliations
Abstract
1 State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
2 Centre for Micro-Photonics, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, VIC 3122, Australia
3 Melbourne Centre for Nanofabrication, ANFF, 151 Wellington Road, Clayton, VIC 3168, Australia
4 State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Haidian, Beijing 100084, China
Femtosecond laser machining of biomimetic micro/nanostructures with high aspect ratio (larger than 10) on ultrahard materials, such as sapphire, is a challenging task, because the uncontrollable surface damage usually results in poor surface structures, especially for deep scribing. Here, we report an inside-out femtosecond laser deep scribing technology in combination with etching process for fabricating bio-inspired micro/nanostructures with high-aspect-ratio on sapphire. To effectively avoid the uncontrollable damage at the solid/air interface, a sacrificial layer of silicon oxide was employed for surface protection. High-quality microstructures with an aspect ratio as high as 80:1 have been fabricated on sapphire surface. As a proof-of-concept application, we produced a moth-eye inspired antireflective window with sub-wavelength pyramid arrays on sapphire surface, by which broadband (3–5 μm) and high transmittance (98% at 4 μm, the best results reported so far) have been achieved. The sacrificial layer assisted inside-out femtosecond laser deep scribing technology is effective and universal, holding great promise for producing micro/nanostructured optical devices.
Author Affiliations
Abstract
1 State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012, China
2 Hooke Instruments, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China
3 State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Haidian, Beijing 100084, China
Natural creatures that enables controllable liquid transport provides the inspiration for developing novel microfluidic devices by engineering functional surfaces with superwettability. However, towards microfluidic applications, the strict requirements of sophisticated droplet manipulation make it challenging to reach this end. In this work, we report a conceptually new self-propelled droplet manipulation strategy based on reconfigurable superhydrophobic chips. The modular droplet chip (MDC) is developed by laser embossing a series of superhydrophobic structures on elastomer jigsaws that act as functional units. MDC is potable since only gravity is used as the driving force for dynamic manipulation of liquid droplets, including droplets transporting, splitting, merging and bouncing without mass loss. The MDC demonstrated reasonable anti-cross-contamination property due to the water repellence of the superhydrophobicity. Modular assembly of MDC enables different chip functions including solution dilution, SERS detection, cell labeling and chemical synthesis. As a miniature and portable experimental platform, the MDC is promising for next-generation lab-on-a-chip systems.
Author Affiliations
Abstract
State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing 100084, China
Nonlinear optical effects have enabled numerous applications such as laser frequency conversion, ultrafast electro-optical, and all-optical modulation. Both gaseous and bulk media have conventionally been used for free-space nonlinear optical applications, yet they often require complex phase-matching techniques for efficient operation and may have limited operation bandwidth due to the material absorption. In the last decade, meta-optics made of subwavelength antennas or films have emerged as novel nonlinear optical media that may potentially overcome certain limitations of bulk crystals. Due to resonant enhancements of the pump laser field as well as the use of materials with extreme nonlinearity such as epsilon-near-zero materials, meta-optics can achieve strong nonlinear responses with a subwavelength thickness. Here, we review several nonlinear optical applications, such as electric-field-induced second-harmonic generation, entangled photon pair generation, terahertz generation, all-optical modulation, and high-harmonic generation that we envision meta-optics may have distinct advantages over their bulk counterparts. We outline the challenges still faced by nonlinear meta-optics and point out some potential directions.
Author Affiliations
Abstract
1 State Key Lab of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
2 State Key Lab of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing 100084, China
3 College of Physics, Jilin University, Changchun 130012, China
We report a feasible method to realize tunable surface plasmon-polariton (SPP) resonance in organic light-emitting devices (OLEDs) by employing corrugated Ag-Al alloy electrodes. The excited SPP resonance induced by the periodic corrugations can be precisely tuned based on the composition ratios of the Ag-Al alloy electrodes. With an appropriate composition ratio of the corrugated alloy electrode, the photons trapped in SPP modes are recovered and extracted effectively. The 25% increasement in luminance and 21% enhancement in current efficiency have been achieved by using the corrugated Ag-Al alloy electrodes in OLEDs.
organic light-emitting devices alloy electrodes tunable surface plasmon-polariton resonance periodic corrugation light extraction Opto-Electronic Advances
2021, 4(8): 08200024
Author Affiliations
Abstract
1 State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
2 State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing 100084, China
3 e-mail: handongdong@jlu.edu.cn
4 e-mail: yonglaizhang@jlu.edu.cn
Supercapacitors (SCs) have broad applications in wearable electronics (e.g., e-skin, robots). Recently, graphene-based supercapacitors (G-SCs) have attracted extensive attention for their excellent flexibility and electrochemical performance. Laser fabrication of G-SCs exhibits obvious superiority because of the simple procedures and integration compatibility with future electronics. Here, we comprehensively summarize the state-of-the-art advancements in laser-assisted preparation of G-SCs, including working mechanisms, fabrication procedures, and unique characteristics. In the working mechanism section, electric double-layer capacitors and pseudo-capacitors are introduced. The latest advancements in this field are comprehensively summarized, including laser reduction of graphene oxides, laser treatment of graphene prepared from chemical vapor deposition, and laser-induced graphene. In addition, the unique characteristics of laser-enabled G-SCs, such as structured graphene, graphene hybrids, and heteroatom doping graphene-related electrodes, are presented. Subsequently, laser-enabled miniaturized, stretchable, and integrated G-SCs are also discussed. It is anticipated that laser fabrication of G-SCs holds great promise for developing future energy storage devices.
Photonics Research
2020, 8(4): 04000577
Author Affiliations
Abstract
1 State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing 100084, China
2 State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
With high hardness, high thermal and chemical stability and excellent optical performance, hard materials exhibit great potential applications in various fields, especially in harsh conditions. Femtosecond laser ablation has the capability to fabricate three-dimensional micro/nanostructures in hard materials. However, the low efficiency, low precision and high surface roughness are the main stumbling blocks for femtosecond laser processing of hard materials. So far, etching-assisted femtosecond laser modification has demonstrated to be the efficient strategy to solve the above problems when processing hard materials, including wet etching and dry etching. In this review, femtosecond laser modification that would influence the etching selectivity is introduced. The fundamental and recent applications of the two kinds of etching assisted femtosecond laser modification technologies are summarized. In addition, the challenges and application prospects of these technologies are discussed.
femtosecond laser hard materials wet etching dry etching Opto-Electronic Advances
2019, 2(9): 09190021
