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C-band tunable performance of passively Q-switched erbium-doped fiber laser using Tin(IV) oxide as a saturable absorber
摘要： We report on the detailed study of wavelength tunability of passively Q-switched erbium doped fiber laser using Tin(IV) Oxide (SnO2) as saturable absorber (SA). As a typical n-type semiconductor, SnO2 has been widely used in gas sensors, oxidation catalyst, transparent conductor, and electrode materials in solar cell. Herein, we fabricated saturable absorber by compositing SnO2 nanoparticle with polyvinyl alcohol (PVA). The SnO2-SA is incorporated in the laser cavity by sandwiching it between two fiber ferrules. Q-switched laser operation can be continuously tuned from 1521 to 1565 nm, with a wavelength tuning range of up to 45 nm, covering almost the entire C-band. Q-switched pulse parameters such as repetition rate, average power, pulse width, pulse energy, and peak power at different wavelengths were studied in detail. Our experimental results suggest that the SnO2-SA is a suitable and cost-effective solution for broadband tunable laser applications with relatively simple fabrication process.
关键词： Tunability,C-band,Q-switch EDFL,SnO2
更新于2025-11-28 14:24:03
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Narrow-Strip 670 nm Gain-Coupled Distributed Feedback Laser Based on Periodic Anodes Fabricated by I-Line Lithography
摘要： A narrow-strip single-longitudinal-mode gain-coupled distributed feedback semi-conductor laser with a central wavelength of approximately 670 nm is demonstrated. We fabricate a novel micro-scale regrowth-free gain-coupled grating with an island-like shape without nanoscale gratings by i-line lithography only. The maximum output power from the ?ber of the device with butter?y package is 48.1 mW at 100 mA and its slope ef?ciency is 0.79 W/A. The laser can be continuously tuned from 670.750 to 670.784 nm with a side-mode suppression ratio of over 40 dB, covering the absorptive peak of lithium atoms. Our easily fabricated devices have great potential as light sources in many applications such as lithium atom detectors.
关键词： continuous tunability,gain-coupled,distributed-feedback,Semiconductor laser
更新于2025-11-28 14:23:57
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Stable, Color-Tunable 2D SCN-Based Perovskites: Revealing the Critical Influence of Asymmetric Pseudo-Halide on Constituent Ions
摘要： Two-dimensional (2D) layered perovskites (An+1BnX3n+1, n = 1, 2, …) have lately attracted significant research interest because of their enhanced ambient stability comparing to the conventional 3D counterparts. Beside the common A-site cation engineering, using an asymmetric pseudo-halide, SCN, anion in X-site anion has been recently proven as another effective approach to constitute 2D perovskite. Among them, 2D (MA)2Pb(SCN)2I2 was most widely investigated and honored as a promising material owing to its decent optoelectronic properties; however, its poor stability arouses concerns from the recent researches. In this study, a systematical composition engineering of A2Pb(SCN)2X2 (A= FA+, MA+, Cs+ and X= Br-, I-) was conducted. Our results revealed that linear SCN- anion may dictate critical restrictions on the constituent ions of its derived 2D framework (PbX4(SCN)2), which has not been extensively discussed yet. We demonstrated that using a smaller Cs+ cation can afford a more favorable 2D structure compared with the MA+ cation. Cs2Pb(SCN)2I2 was revealed to possess improved stability and photo-response compared to (MA)2Pb(SCN)2I2. Interestingly, Cs2Pb(SCN)2I2 and (MA)2Pb(SCN)2I2 seem to possess distinct electronic band structures as indicated by their discrepant photoluminescence spectra, for which the former exhibits a rather intense singlet emission at room temperature, as opposed to the latter having a dominant emission associated with triplet or defective states. Furthermore, using a smaller Cs+ cation also enables facile replacement of smaller halide anion. A series of mix-halide 2D Cs2Pb(SCN)2(I1-xBrx)2 (x = 0, 1/3, 1/2, 2/3, 1) with variant vivid color was explored by both calculation and experimental efforts to corroborate the further enhanced stability when x value increases. The results revealed in this work might be inherent trait of 2D SCN-based perovskites and also unveil that all inorganic 2D Cs2Pb(SCN)2X2 perovskite system is a promising class of material with decent stability and color-tunability, deserving further explorations.
关键词： stability,Cs cation,pseudo-halide,SCN- anion,color-tunability,2D perovskite
更新于2025-11-14 17:04:02
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Structural and dielectric properties of PLD grown BST thin films
摘要： Thin films of Barium Strontium Titanate (BaSrTiO3, BST) have been deposited on platinised silicon substrate using pulsed laser deposition (PLD) technique. The effect of growth pressure and temperature during the film deposition on the crystallization and dielectric behaviour of the BST films has been studied. The effect of plume dynamics due to variation in deposition parameters present inside the deposition chamber has also been investigated. The dielectric constant of the BST thin film deposited under variable deposition pressures increases with increase in deposition temperature at a frequency of 1 MHz. The BST thin film deposited at 1.33 × 10?4 bar and 800 °C substrate temperature exhibits high dielectric constant (≈475) with 65% tunability which can be efficiently exploited for the realization of tunable resonators and filters.
关键词： Barium Strontium Titanate,BST,PLD,tunability,dielectric properties
更新于2025-09-23 15:21:21
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[IEEE 2018 11th UK-Europe-China Workshop on Millimeter Waves and Terahertz Technologies (UCMMT) - HangZhou, China (2018.9.5-2018.9.7)] 2018 11th UK-Europe-China Workshop on Millimeter Waves and Terahertz Technologies (UCMMT) - A Fabry-Perot Resonator Antenna based on Graphene Patch Array
摘要： In order to achieve a high directivity antenna for terahertz, an improved Fabry-Perot resonator antenna based on graphene is proposed. The antenna consists of a graphene patch array on a grounded dielectric and a rectangle waveguide. According to the theory of Fabry-Perot resonant cavity, the directivity of antenna will increase obviously by choosing proper chemical potential of graphene and appropriate distance of resonant cavity. The radiation pattern of antenna also changes with the chemical potential.
关键词： Terahertz,Antenna,Graphene,tunability,Fabry-Perot resonator
更新于2025-09-23 15:21:01
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Bandgap tunable Zn3-3Mg3N2 alloy for earth-abundant solar absorber
摘要： Zn3-3xMg3xN2 alloy layers with x ≤ 0.3 can be epitaxially grown at a temperature as low as 140 oC. The bandgap (Eg) of Zn3-3xMg3xN2 widens from 1.2 to 2.1 eV with increasing x. The Eg value of 1.4 eV is obtained at x = 0.18, and the x = 0.18 film has a large absorption coefficient (104-105 cm-1) in the visible region. The Zn3-3xMg3xN2 with Eg = 1.4 eV shows n-type conductivity with a reasonably high electron mobility of 47 cm2 V-1 s-1. Therefore, Zn3-3xMg3xN2 is a candidate for an earth-abundant solar absorber that can be fabricated at low temperatures.
关键词： Nitride alloy,Bandgap tunability,Photovoltaic semiconductors,Sputtering
更新于2025-09-23 15:21:01
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Development of a continuously tunable titanium-sapphire laser system for the ARIEL laser ion source
摘要： A concept for continuously tunable titanium-sapphire (Ti:Sa) lasers using dispersion prisms is under investigation for the ARIEL (Advanced Rare IsotopE Laboratory) laser ion source at TRIUMF (Canada’s particle accelerator center). Wavelength selection for pulsed Ti:Sa lasers used in hot cavity laser resonance ionization spectroscopy is usually done with birefringent filters (BRFs) and etalons or diffraction gratings. For resonance ionization spectroscopy a laser system allowing a continuous wavelength scan is necessary. Tunable lasers based on BRFs and etalons have high output powers however require synchronized optimization for continuous laser wavelength scans and are therefore laborious to use in scanning applications. Diffraction grating tuned lasers can provide continuous wavelength scan over 200 nm range but typically have lower output laser power due to the grating deformation under high pumping power. Aiming to overcome both shortcomings a laser design based on prisms as dispersing element has been revisited. Simulations on the beam path and optical reflectivity are done which show that these losses can be minimized to around 0.04 % for a tuning range from 700 nm up to 920 nm. Further improvement on the tuning range and reduction on the linewidth will be pursued.
关键词： Titanium-sapphire laser,Tunability,Prisms
更新于2025-09-23 15:21:01
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Tunability of the Freea??Spectral Range by Microwave Injection into a Mida??Infrared Quantum Cascade Laser
摘要： The free-spectral range (FSR) of quantum cascade lasers (QCLs) emitting at 4.7 μm can be tuned through direct microwave modulation. The intrinsic short carrier lifetime of inter-subband transitions, along with impedance matched electrical packaging, allows a high-speed modulation up to more than 30 GHz. A signi?cant broadening and ?attening of the lasing spectrum is observed under radio frequency (RF) injection with frequencies close to the round-trip cavity. An accurate analysis of the high resolution spectra of the laser shows a comb-like regime for both free-running and RF modulated QCLs, if the modulation frequency is within the locking-range of the device. One of the main advantages of collecting high-resolution mid-infrared spectra, over the plain investigation of the beatnote in the microwave region, is the access to all the longitudinal modes and thus the accurate measure of the FSR over the whole optical spectrum. The use of high-resolution spectroscopy provides an in-depth and comprehensive analysis of lasing spectra under microwave modulations.
关键词： quantum devices,mid-infrared region,injection locking,tunability of the free-spectral-range,ultrafast devices
更新于2025-09-23 15:19:57
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Photodetectors based on solution-processable semiconductors: Recent advances and perspectives
摘要： The detection of light, one of the most important technologies, has widespread applications in industry and our daily life, e.g., environmental monitoring, communications, surveillance, image sensors, and advanced diagnosis. Along with the remarkable progress in the field of organics, those based on quantum dots, and recently emerged perovskite optoelectronics, photodetectors based on these solution-processable semiconductors have shown unprecedented success. In this review, we present the basic operation mechanism and the characterization of the performance metrics based on these novel materials systems. Then, we focus on the current research status and recent advances with the following five aspects: (i) spectral tunability, (ii) cavity enhanced photodetectors, (iii) photomultiplication type photodetectors, (iv) sensitized phototransistors, and (v) ionizing radiation detection. At the end, we discuss the key challenges facing these novel photodetectors toward manufacture and viable applications. We also point out the opportunities, which are promising to explore and may require more research activities.
关键词： sensitized phototransistors,photodetectors,cavity enhanced photodetectors,solution-processable semiconductors,photomultiplication type photodetectors,spectral tunability,ionizing radiation detection
更新于2025-09-23 15:19:57
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Two-dimensional Ruddlesdena??Popper layered perovskite for light-emitting diodes
摘要： Solution-processed metal halide perovskite light-emitting diodes (PeLEDs) have attracted extensive attention due to the great potential application in energy-efficient lighting and displays. Two-dimensional Ruddlesden–Popper (2DRP) layered perovskites exhibit high photoluminescence quantum efficiency, improved film morphology, and enhanced operational stability over their three-dimensional counterparts, making them attractive for high-performance PeLEDs. In addition, 2DRP perovskite materials with a tunable exciton binding energy are suitable for preparing PeLEDs with color-tunability. In this perspective, we first introduce the merits of the 2DRP layered perovskites in terms of their structural characteristics. The progress in 2DRP PeLEDs is then reviewed. The challenges and new opportunities of the PeLEDs are finally discussed. We hope to open up new perspectives for rational designs of the 2DRP perovskite materials for PeLEDs with unprecedented efficiency and stability.
关键词： operational stability,film morphology,photoluminescence quantum efficiency,Two-dimensional Ruddlesden–Popper layered perovskite,color-tunability,light-emitting diodes
更新于2025-09-19 17:13:59