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Robust 1.7-μm, all-polarization-maintaining femtosecond fiber laser source based on standard telecom fibers
摘要： We demonstrate a compact 1.7-μm all-polarization-maintaining (PM) ultrafast fiber laser source, which employs soliton self-frequency shift (SSFS) in an optical fiber as the dominant spectral-shifting mechanism. The laser generates stable pulses with 384 fs pulse width and 102 MHz repetition rate centered at 1.7 μm with 7 nm spectral bandwidth. The average power is about 35 mW with a high conversion efficiency of 66 %. The measured root mean square (RMS) output power stability over 10 hours is as low as 0.22 %. Both experimental and simulation results demonstrate that this laser has a potential to improving multiphoton imaging depth.
关键词： all-polarization-maintaining,multiphoton imaging,femtosecond fiber laser,soliton self-frequency shift,1.7-μm
更新于2025-11-28 14:23:57
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Femtosecond Pulse Laser Near-Field Ablation of Ag Nanorods
摘要： Ag nanorods (Ag NRs) with a mean aspect ratio of 3.9 were prepared through a wet-chemical method, and the absorption spectra for various aspect ratios were obtained. The morphology transformation of Ag NRs irradiated with a femtosecond pulse laser was investigated through transmission electron microscopy (TEM). The near-field ablation was dependent on the laser polarization and wavelength. Laser-induced high electric field intensity was observed at the ends, middle, and junctions of the Ag NRs under various ablation conditions. Through simulation, the evolution mechanism was analyzed in detail. The effect of laser polarization angle on plasmonic junction welding was also investigated. By controlling the electronic field distribution, several nanostructures were obtained: bone-shaped NRs, T-shaped NRs, dimers, trimers, curved NRs, and nanodots. This study suggests a potentially useful approach for the reshaping, cutting, and welding of nanostructures.
关键词： femtosecond pulse laser,polarization,Ag nanorods,near-field ablation
更新于2025-11-14 17:04:02
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Upconversion photoluminescence modulation by electric field poling in Er3+ doped (Ba0.85Ca0.15) (Zr0.1Ti0.9)O3 piezoelectric ceramics
摘要： Luminescent piezoelectric materials promise a stratagem for controlling the optical process by electric field, which would benefit for future optoelectronic devices. Here, Er3+ doped (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 (BCZT: Er3+) piezoelectric ceramics are prepared to demonstrate the proof of concept. In addition to excellent intrinsic piezoelectricity and ferroelectricity, BCZT: Er3+ ceramics exhibit simultaneously strong green upconversion emissions under excitation of 980 nm. Remarkable photoluminescence (PL) quenching phenomenon as well as significant changes on relative intensities of stark lines are observed under external poling electric field. Furthermore, field dependent piezoelectric constant d33 and photoluminescence quenching ratio show similar variation trend and finally saturate for E>3.5 kV/mm, which provides a noncontact strategy to monitor the piezoelectric constant d33. The PL quenching triggered by electric field in BCZT: Er3+ ceramics is ascribed to the decreased asymmetry originating from field-induced structural transformation from a significant fraction of the tetragonal phase to rhombohedral phase. Our work would be helpful for expanding the scope of luminescent piezoelectric materials and promising future optoelectronic and optical devices with cross-coupled physical properties.
关键词： Piezoelectric,Electric field poling,Photoluminescence,Ferroelectric polarization
更新于2025-11-14 15:28:36
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Enhanced visible-light-driven photocatalytic activity of BiFeO3 via electric-field control of spontaneous polarization
摘要： Well-polarized BiFeO3 nanoparticles have been successfully prepared by a facile electrical poling method with the assist of a soluble organic-inorganic composite film. From XRD, TEM and SEM studies, no significant change in the crystal structure or morphology was detected after the electrical poling process. The visible-light driven photocatalytic process of poled BiFeO3 nanoparticles was accelerated by 2 times compared to unpoled BiFeO3. By combining time-resolved photoluminescence (PL), photoinduced silver deposition testing and photoelectrochemical measurements, it can be revealed that the enhanced photocatalytic performance of poled samples can be properly attributed to the promoted separation and prolonged lifetime of the photogenerated carriers caused by the ferroelectric polarization. These findings may offer a new route to promote the photocatalytic or photoelectric performances of BiFeO3 for advanced applications by adjusting the ferroelectric polarization.
关键词： BiFeO3 nanoparticles,Organic-inorganic composite film,Ferroelectric polarization,Electrical poling technology,Photocatalytic activity
更新于2025-11-14 15:24:45
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Anisotropic infrared light emission from quasi-one-dimensional layered TiS<sub>3</sub>
摘要： Atomically thin semiconductors hold great potential for nanoscale photonic and optoelectronic devices because of their strong light absorption and emission. Despite progress, their application in integrated photonics is hindered particularly by a lack of stable layered semiconductors emitting in the infrared part of the electromagnetic spectrum. Here we show that titanium trisulfide (TiS3), a layered van der Waals material consisting of quasi-one-dimensional chains, emits near infrared light centered around 0.91 eV (1360 nm). Its photoluminescence exhibits linear polarization anisotropy and an emission lifetime of 210 ps. At low temperature, we distinguish two spectral contributions with opposite linear polarizations attributed to excitons and defects. Moreover, the dependence on excitation power and temperature suggests that free and bound excitons dominate the excitonic emission at high and low temperatures, respectively. Our results demonstrate the promising properties of TiS3 as a stable semiconductor for optoelectronic and nanophotonic devices operating at telecommunication wavelengths.
关键词： infrared luminescence,transition metal trichalcogenides,titanium trisulfide,linear polarization anisotropy,layered semiconductors
更新于2025-11-14 14:32:36
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Rotated infrared antenna transmitarray for the manipulation of circularly polarized wavefronts
摘要： An IR optical transmitarray is presented based on Antenna Array Sheet (AAS) for the manipulation of circularly polarized light. The unit cell of the transmitarray comprises three layers of metallic elliptical patches. Complete phase control is achieved through the local rotation of each unit cell. Thin refraction and focusing transmitarrays of this sort are demonstrated at infrared frequencies. Moreover, a new concept for realizing a polarization-discriminating device is introduced based on a flat refracting lens. These devices are compatible with current fabrication technology and can become crucial for the integration with other IR and nano-photonic devices.
关键词： Metasurfaces,Transmitarrays,Polarization discrimination,Infrared lens,Circular polarization
更新于2025-09-23 15:23:52
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Polarization Reconfigurable Corner Truncated Square Microstrip Array Antenna
摘要： In this paper, a simple 2 × 2 polarization reconfigurable planar microstrip array antenna is presented. It is based on electrical switching technology using PIN diodes. Each element of the array is excited with the aid of the corporate feed technique. Each element of the proposed structure consists of a corner truncated square patch connected to parasitic triangular conductors by means of PIN diodes. The array element is configured to facilitate linear polarization (LP), right-hand circular polarization (RHCP) or left-hand circular polarization (LHCP) by means of 4 independently biased PIN diodes. The proposed antenna is designed and simulated using electromagnetic simulation software CST Microwave Studio. In order to experimentally validate the design, a prototype is fabricated on a 1.6 mm thick RT Duroid substrate of relative permittivity εr = 2.2. The performance of the antenna is validated experimentally using 16 PIN diodes. The simulation and measured results for all the polarization states of the array antenna are found to be in good agreement. The measured results have established the polarization reconfigurable ability of the antenna for 5.7–6.0 GHz operating band. The proposed antenna is suitable for C-band point-to-point communication applications.
关键词： PIN diode switch,polarization reconfigurable,corporate feed network,reconfigurable antenna,Array antenna,circular polarization
更新于2025-09-23 15:23:52
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An interferometric structure with a dual-resonance long period grating for strain sensing
摘要： Spectral characteristics and amplitude tunability of a long period grating with a dual-resonance inside fiber loop mirror are studied in terms of applied stress caused by elongation. Inserting the polarization controller between grating and part of polarization maintaining fiber in the loop structure enables tuning of resonance and interferometric peaks. The maximum sensitivity of demonstrated sensor is of 1.943 dB/mε for the range of 1.1–4.4 mε. Combination of these two optical components allows to measure strain in a wider range comparing with sensors based on standard long period grating.
关键词： Fiber loop mirror,Polarization controller,Polarization maintaining fiber,Strain sensor,Long period grating
更新于2025-09-23 15:23:52
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[IEEE 2018 International Conference on Advances in Computing, Communications and Informatics (ICACCI) - Bangalore, India (2018.9.19-2018.9.22)] 2018 International Conference on Advances in Computing, Communications and Informatics (ICACCI) - High Performance Dual Circularly Polarized Microstrip Patch Antenna for Satellite Communication
摘要： High performance dual circularly polarized X-band microstrip patch antenna for satellite communication is presented in this paper. The high performance refers to high return loss, high isolation, high gain >8.5dBi and low cross polarization with axial ratio<2dB throughout the bandwidth 8–8.4GHz. This performance is achieved by using stacked substrate with square patch on the top layer and a 90? hybrid coupler on the bottom layer. The patch is electromagnetically coupled through the two apertures present on the ground plane which is fed by the branchline coupler present on the bottom substrate. Simulated and measured results shows that this basic element can be extended to form a phased array antenna due to its less weight,compact structure and high performance.
关键词： dual circular polarization,broadband antenna,low cross polarization,high isolation,Aperture coupled antenna
更新于2025-09-23 15:23:52
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A dual-band efficient circularly polarized rectenna for RF energy harvesting systems
摘要： A multilayered circularly polarized (CP), dual-band, stacked slit-/slotted-patch antenna with compact size and with compact rectifier is offered for RF energy harvesting systems. The compact dual-band CP antenna size is able to achieve by stacking slotted-circular-patch (SCP) on the substrate above the tapered-slit-octagon patch (TSOP). Dual-band CP radiation is realized by stacking the SCP on the TSOP and the microstrip feedline with metallic-via to SCP. Eight-tapered-slit with length difference of 6.25% are embedded along the octagonal directions symmetrically on the TSOP from the patch's center and two unequal size circular slots are embedded in diagonal axis onto SCP to produce dual-orthogonal modes with almost equal magnitude for CP waves. The designed antenna is realized measured gain of greater than 5.2 dBic across the band (0.908-0.922 GHz) with maximum gain of 5.41 dBic at 0.918 GHz and gain of greater than 6.14 dBic across the band (2.35-2.50 GHz) with maximum gain of 7.94 dBic at 2.485 GHz. An overall antenna volume is 0.36λo × 0.36λo × 0.026λo (λo is free space wavelength at 0.9 GHz). A compact composite right-/left-handed (CRLH) based rectifier with dual-band at 0.9 and 2.45 GHz is designed, prototyped, and measured. The right-handed (RH) part of the CRLH transmission line (TL) is formed by a microstrip line. The left-handed (LH) part of the CRLH-TL is formed by lumped components. The measured RF-DC conversion efficiency is 43% at 0.9 GHz and 39% at 2.45 GHz with rectifier size of 0.18λo × 0.075λo × 0.0002λo at 0.9 GHz.
关键词： slotted-patch,stacked antenna,energy harvesting,rectenna,rectifier,circular polarization,dual-band
更新于2025-09-23 15:23:52