- 标题
- 摘要
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- 实验方案
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Definition of design guidelines, construction, and performance of an ultra-stable scanning tunneling microscope for spectroscopic imaging
摘要： Spectroscopic-imaging scanning tunneling microscopy is a powerful technique to study quantum materials, with the ability to provide information about the local electronic structure with subatomic resolution. However, as most spectroscopic measurements are conducted without feedback to the tip, it is extremely sensitive to vibrations coming from the environment. This requires the use of laboratories with low-vibration facilities combined with a very rigid microscope construction. In this article, we report on the design and fabrication of an ultra-stable scanning tunneling microscope (STM) for spectroscopic-imaging measurements that operates in ultra-high vacuum and at low temperatures (4 K). We start from existing designs with sapphire as the main material and improve the stiffness further by performing finite element analysis calculations for the main components of the microscope to guide design choices on the geometry of the parts. With this strategy, we construct a STM head with measured lowest resonant frequencies above f0 = 13 kHz for the coarse approach mechanism, a value three times higher than what has been previously reported and in good agreement with the calculations. This allows us to achieve an average vibration level of ～6 fm/√Hz, without a dedicated low-vibration lab. We demonstrate the microscope’s performance with topographic and spectroscopic measurements on the correlated metal Sr2RhO4, showing the quasiparticle interference pattern in real and reciprocal space with high signal-to-noise ratio.
关键词： ultra-high vacuum,low temperature,spectroscopic imaging,finite element analysis,ultra-stable,scanning tunneling microscopy
更新于2025-09-23 15:23:52
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Transportable 1555-nm Ultra-Stable Laser with Sub-0.185-Hz Linewidth
摘要： We present two cavity-stabilized lasers at 1555 nm, which are built to be the frequency source for a transportable photonic microwave generation system. The frequency instability reaches the thermal noise limit (7 × 10?16) of the 10-cm ultra-low expansion glass cavity at 1–10 s averaging time and the beat signal of the two lasers reveals a remarkable linewidth of 185 mHz.
关键词： cavity-stabilized,linewidth,frequency instability,1555-nm ultra-stable laser
更新于2025-09-23 15:19:57
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Room-temperature operation of near-infrared light-emitting diode based on Tm-doped GaN with ultra-stable emission wavelength
摘要： Near-infrared (NIR) light with a wavelength of 650–950 nm is used for various biomedical applications. Although NIR emitters are typically based on GaAs-related materials, they contain toxic elements, and the emission wavelength can easily shift during the device operation due to temperature changes and current injection levels. On the other hand, Tm3t, which is one of the rare-earth ions, can generate ultra-stable NIR luminescence with a wavelength of (cid:1)800 nm, based on 3H4 – 3H6 transitions in a 4f shell, and we have recently focused on Tm-doped GaN (GaN:Tm) based light-emitting diodes (LEDs) as novel NIR emitters. In this paper, we present a demonstration of a NIR-LED based on GaN:Tm grown by the organometallic vapor phase epitaxy method with optimized growth conditions and structures, where the parasitic reaction is well suppressed. NIR luminescence from the GaN:Tm-based LED is derived from 3H4 – 3H6 transitions of Tm3t ions and consists of three dominant peaks at 795, 806, and 814 nm. The turn-on voltage of the NIR-LED is (cid:1)6:9 V, and it is significantly lower than the previously reported electroluminescent devices based on GaN:Tm with impact ionization processes. From a current dependence of the electroluminescence spectra and temperature-dependent photoluminescence for the NIR-LED, the peak shifts are determined to be ,7:6 pm/mA and (cid:1)1:3 pm/K, respectively.
关键词： Tm-doped GaN,ultra-stable emission wavelength,Near-infrared,organometallic vapor phase epitaxy,light-emitting diode
更新于2025-09-23 15:19:57
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[IEEE 2019 Joint Conference of the IEEE International Frequency Control Symposium anEuropean Frequency and Time Forum (EFTF/IFC) - Orlando, FL, USA (2019.4.14-2019.4.18)] 2019 Joint Conference of the IEEE International Frequency Control Symposium and European Frequency and Time Forum (EFTF/IFC) - Development of Ultra-stable Clock Laser System for Space Applications
摘要： The National Time Service Centre of China is developing a 698 nm ultra-stable clock laser system for dedicated use in a space strontium optical clock. This report present the development of this system. The laser reaches a frequency instability of 3.5×10?15 at 1 s averaging time and the linewidth is about 1.3 Hz.
关键词： Laser stabilization,Ultra-stable laser,Fabry-Perot
更新于2025-09-19 17:13:59
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Stabilizing diode laser to 1?Hz-level Allan deviation with atomic spectroscopy for Rb four-level active optical frequency standard
摘要： We achieve a compact ultra-stable 420 nm blue diode laser system by immediately stabilizing the laser on the hyperfine transition line of Rb atom. The Allan deviation of the residual error signal reaches 1 Hz-level Allan deviation within 1 s averaging time, and the fractional frequency Allan deviation is 1.4 × 10?15∕√?? , which shows the best result of frequency-stabilized lasers based on the atomic spectroscopy without Pound–Drever–Hall (PDH) system. The signal-to-noise ratio of the atomic spectroscopy is evaluated to be 3,000,000 from the Allan deviation formula, which is the highest record, to the best of our knowledge. The frequency noise suppression characterization is demonstrated and the maximal noise suppression can be near 40 dB at 6 Hz. As a good candidate of pumping source, the ultra-stable 420 nm diode laser is successfully used in our Rb four-level active optical frequency standard system. The method can be easily extended to other wavelengths ultra-stable lasers with a Allan deviation of 10?15 level retaining an atomic reference with low cost and low complexity while in the absence of an expensive and complicated PDH system.
关键词： ultra-stable laser,Rb four-level active optical frequency standard,atomic spectroscopy,Allan deviation,frequency noise suppression
更新于2025-09-19 17:13:59
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Development of ultrastable lasers at 1. 5μm
摘要： We report the development of ultrastable lasers at 1.5μm. Through PDH method, the fiber lasers are locked to two ultra-stable optical cavities with finesse of 483000 and 148000 respectively. Through comparing two similar ultrastable laser systems, the linewidth of 0.68Hz and the fractional frequency instability of 2.7×10-15 at 1s averaging time are achieved.
关键词： finesse,ultra-stable laser,fractional frequency instability
更新于2025-09-16 10:30:52
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[IEEE 2019 Joint Conference of the IEEE International Frequency Control Symposium anEuropean Frequency and Time Forum (EFTF/IFC) - Orlando, FL, USA (2019.4.14-2019.4.18)] 2019 Joint Conference of the IEEE International Frequency Control Symposium and European Frequency and Time Forum (EFTF/IFC) - Laser Frequency Stabilization Based on Spectral-Hole Burning Using Double-Heterodyne Detection
摘要： We report a fractional-frequency stability of σy(τ) ≈1.7 × 10-15 near 1 s timescale based on a spectral hole burning (SHB) laser frequency stabilization technique using a novel detection scheme that offer < 10-16 detection noise capability. The current stability level is attributed to residual temperature fluctuations in the cryostat. In addition, we report preliminary results on the measurement of the sensitivity of the spectral hole to uni-axial mechanical strain, which, combined with accelerometric noise measured in our pulse-tube cryostat set the vibration induced fractional stability limit to < 10-17, regardless specially designed crystal mounts.
关键词： Spectral Hole Burning,Ultra-stable Lasers,Metrology
更新于2025-09-16 10:30:52
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An ultra-stable 2.9 μm guided-wave chip laser and application to nano-spectroscopy
摘要： We present a configurable guided-wave planar glass-chip laser that produces low-noise and high-quality continuous-wave laser emission tunable from 2.82 to 2.95 μm. The laser has a low threshold and intrinsic power and mode stability attributable to the high overlap of gain volume and pump mode defined by an ultrafast laser inscribed waveguide. The laser emission is single transverse-mode with a Gaussian spatial profile and M2 x,y ～ 1.05, 1.10. The power drift is ～0.08% rms over ～2 h. When configured in a spectrally free-running cavity, the guided-wave laser emits up to 170 mW. The benefit of low-noise and stable wavelength emission of this hydroxide resonant laser is demonstrated by acquiring high signal-to-noise images and spectroscopy of a corroded copper surface film with corrosion products containing water and hydroxide ions with a scattering-scanning near-field optical microscope.
关键词： ultra-stable,continuous-wave laser emission,guided-wave chip laser,nano-spectroscopy,mid-infrared
更新于2025-09-16 10:30:52
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Swelling‐Deswelling Microencapsulation‐Enabled Ultrastable Perovskite?Polymer Composites for Photonic Applications
摘要： Metal halide perovskite nanocrystals are emerging as novel optoelectronic materials. Owing to their excellent optical and electronic properties such as tunable band gap, narrow-band emission and high charge mobility, they are quite promising in various fields including liquid-crystal display backlighting, solid-state lighting and other energy conversion applications. However, the intrinsic low formation energy makes them vulnerable to external stimulus, e. g. water, oxygen, heat, etc. Among many methods, swelling-deswelling microencapsulation emerges as one of the most promising strategies to improve their stability. Herein, recent developments and future research directions in swelling-deswelling microencapsulation-enabled ultrastable perovskite(cid:0) polymer composites are summarized. We believe this strategy has great potential to deliver successful perovskite-based commercial products for many photonics applications.
关键词： ultra-stable,perovskite nanocrystals,polymer,swelling-deswelling microencapsulation,photoluminescence
更新于2025-09-12 10:27:22
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Synthesis and electroluminescence of novel white fluorescence quantum dots based on a Zn–Ga–S host
摘要： White-light-emitting Ag, Mn: Zn–Ga–S/ZnS quantum dots (QDs) with a gratifying photoluminescence (PL) quantum yield (QY) of up to 90% were prepared, and shown to be ultra-stable, maintaining a high PL intensity at 300 8C or for 32 h of UV illumination. These QDs were employed in a white QD-LED displaying a color rendering index (CRI) of 72 and maximum current efficiency of 0.22 cd A(cid:2)1.
关键词： QD-LED,Quantum dots,Current efficiency,Quantum yield,White-light-emitting,Photoluminescence,Color rendering index,Ultra-stable
更新于2025-09-12 10:27:22