- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
A fast interrogation system of FBG sensors based on low loss jammed-array wideband sawtooth filter
摘要： In this paper, a low loss jammed-array wideband sawtooth (JAWS) filter is built based on a finite reflection virtually imaged array (FRVIA) which has a lower reflectivity of the exit surface compared to a virtually imaged phased array (VIPA). This filter can be used as an edge filter to interrogate the fiber Bragg grating (FBG) sensors. A fast FBG sensing system is set up to detect the strain wave of iron pipe to demonstrate the use of this interrogator. The result shows that the JAWS based interrogation system has advantages of high speed, low loss and high sensitivity.
关键词： JAWS filter,Fiber Bragg grating (FBG) interrogator,Finite reflection virtually imaged array
更新于2025-11-28 14:24:03
-
Ultrafast mode-locked dual-wavelength thulium-doped fiber laser using a Mach-Zehnder interferometric filter
摘要： A simple and robust method to generate a dual-wavelength mode-locked laser using a tunable Mach-Zehnder filter (TMZF) and a single-wall carbon nanotube (SWCNT) based saturable absorber (SA) is proposed and demonstrated. The proposed laser uses a thulium-doped fiber for lasing in the two-micron region and exploits the interferometric spectrum of the TMZF to produce dual peaks with nearly equal magnitude. SWCNT based SA enables mode-locking at a threshold value of 150.4 mW with distinct dual-wavelength peaks at 1919.2 nm and 1963.7 nm. The peaks have a calculated pulse width of 1.8 ps and 1.6 ps, respectively with a repetition rate of 9.1 MHz with a relatively high optical-signal-to-noise ratio value of 59.1 dB. The output is also observed to remain unchanged over time, indicating high stability. The proposed laser has a promising application, particularly in ultrafast gas molecular spectroscopy and sensing.
关键词： Thulium-doped fiber laser,Mode-locking,Dual-wavelength,Mach-Zehnder filter
更新于2025-11-28 14:24:03
-
All-polarization-maintaining dual-wavelength mode-locked fiber laser based on Sagnac loop filter
摘要： We demonstrate an all polarization-maintaining (PM) fiber based dual-wavelength mode-locked Er-fiber laser. A nonlinear amplifying loop mirror (NALM) with an intracavity nonreciprocal phase shifter is used for self-started mode-locking. A short segment of PM fiber is angle-spliced to the NALM, functioning as a PM Sagnac loop filter, thus enabling dual-wavelength mode-locking. The wavelength separation is solely determined by the angle-spliced PM fiber length. Stable dual-wavelength mode-locking operation is switchable between 1570/1581 nm and 1581/1594 nm. The two-color pulse trains oscillating in the same cavity have an inherent offset repetition rate of ~1 kHz owing to cavity dispersion, allowing future high precision dual-comb applications with a simple and robust configuration.
关键词： polarization-maintaining fiber,dual-comb applications,dual-wavelength mode-locked fiber laser,Sagnac loop filter
更新于2025-11-28 14:24:03
-
All-fiber polarization interference filter based uniform multiwavelength erbium-doped fiber laser
摘要： We demonstrate a compact and stable room-temperature multiwavelength erbium doped fiber laser by employing 45° tilted fiber gratings based on an all-fiber polarization interference filter. Benefiting from the filter, the channel number, linewidth, uniformity and stabilization of the multiwavelength laser are greatly improved. The filter also works as a functional polarizing device in a nonlinear polarization rotation, leading to the multiwavelength operation. Instead of a highly nonlinear fiber, the single mode fiber is used to provide enough linearity and to reduce the splice loss. More than 80 wavelengths (within a 3 dB bandwidth), lasing with a linewidth of 0.03 nm and a signal-to-noise ratio of 33 dB, are obtained. The wavelength spacing of 0.164 nm agrees with the channel spacing of the filter, and can be flexibly controlled by adjusting the length of the filter.
关键词： 45° tilted fiber gratings,multiwavelength fiber laser,all-fiber polarization interference filter (AFPIF)
更新于2025-11-28 14:23:57
-
Dual-wavelength thulium/holmium-doped fiber laser generation in 2 <i>μ</i> m region with high side-mode suppression ratio
摘要： We demonstrate a dual-wavelength laser with emission in the 2 μm wavelength region using a thulium/holmium co-doped fiber and a non-adiabatic tapered fiber as a comb filter. The configuration employed a backward pumping scheme and dual-wavelength laser was generated at 2023.53 and 2032.82 nm. The side-mode suppression ratio (SMSR) is more than 44 dB with overall good stability performance. The proposed configuration presents a simple yet practical scheme of generating 2 μm dual-wavelength laser with good SMSR. This investigation may offer a more efficient yet eye safe dual-wavelength related applications for end users.
关键词： comb filter,tapered fiber,side-mode suppression ratio,thulium/holmium-doped fiber laser,dual-wavelength laser
更新于2025-11-28 14:23:57
-
Triple-Junction Optoelectronic Sensor with Nanophotonic Layer Integration for Single Molecule Level Decoding
摘要： Interest in developing a rapid and robust DNA sequencing platform has surged over the past decade. Various next-/third-generation sequencing mechanisms have been employed to replace the traditional Sanger sequencing method. In sequencing by synthesis (SBS), a signal is monitored by a scanning charge-coupled device (CCD) to identify thousands to millions of incorporated dNTPs with distinctive fluorophores on a chip. Because one reaction site usually occupies dozens of pixels on a CCD detector, a bottleneck related to the bandwidth of CCD imaging limits the throughputs of the sequencing performance and causes tradeoffs among speed, accuracy, read length, and the numbers of reaction sites in parallel. Thus, current research aims to align one reaction site to a few pixels by directly stacking nanophotonic layers (NPLs) onto a CMOS detector to minimize the size of the sequencing platforms and accelerate the processing procedures. This article reports a custom integrated optoelectronic device based on a triple-junction photodiode (TPD) CMOS sensor in conjunction with NPL integration for real-time illumination and detection of fluorescent molecules.
关键词： planar waveguide,nanophotonic layer,CMOS,triple-junction photodiode (TPD),filter,grating
更新于2025-11-25 10:30:42
-
Automatic Mapping of Center Line of Railway Tracks using Global Navigation Satellite System, Inertial Measurement Unit and Laser Scanner
摘要： Up-to-date geodatasets on railway infrastructure are valuable resources for the field of transportation. This paper investigates three methods for mapping the center lines of railway tracks using heterogeneous sensor data: (i) conditional selection of satellite navigation (GNSS) data, (ii) a combination of inertial measurements (IMU data) and GNSS data in a Kalman filtering and smoothing framework and (iii) extraction of center lines from laser scanner data. Several combinations of the methods are compared with a focus on mapping in tree-covered areas. The center lines of the railway tracks are extracted by applying these methods to a test dataset collected by a road-rail vehicle. The guard rails in the test area were also extracted during the center line detection process. The combination of methods (i) and (ii) gave the best result for the track on which the measurement vehicle had moved, mapping almost 100% of the track. The combination of methods (ii) and (iii) and the combination of all three methods gave the best result for the other parallel tracks, mapping between 25% and 80%. The mean perpendicular distance of the mapped center lines from the reference data was 1.49 meters.
关键词： Inertial Measurement Unit,Global Navigation Satellite System,automated mapping,Kalman filter,laser scanner,railway tracks
更新于2025-11-21 11:01:37
-
A sensitive polymer dots fluorescent sensor for determination of α-L-fucosidase activity in human serum
摘要： α-L-Fucosidase (AFu) is an important biomarker for early diagnosis of hepatocellular carcinoma and fucosidosis. In this study, a novel, sensitive and selective polymer dots (PDs) fluorescent sensing strategy based on inner filter effect was firstly developed for AFu activity determination. The PDs with a high quantum yield of 53.6% were synthesized by a mild one-pot method. The detection mechanism of this strategy was based on inner filter effect between PDs and p-nitrophenol (PNP) which was the hydrolyzate of 4-nitrophenyl-α-L-fucopyranoside (PNPF) catalyzed by AFu. The absorption of PNP overlapped the fluorescence excitation spectrum of the PDs, which resulted in a fluorescence quenching or weakening of PDs. The sensing system showed a good linear relationship within 0.01-0.9 U L-1 and provided a low AFu detection limit of 0.001 U L-1 (S/N=3). This PDs sensor were successfully applied for the determination of AFu in human serum samples.
关键词： Human serum,α-L-Fucosidase,Polymer dots,Inner filter effect,Fluorescent sensor
更新于2025-11-19 16:46:39
-
A fluorescent probe for sequential sensing of MnO <sub/>4</sub><sup>?</sup> and Cr <sub/>2</sub> O <sub/>7</sub><sup>2?</sup> ions in aqueous medium based on a UCNS/TMB nanosystem
摘要： This paper reports the successful design of an UC fluorescence nanosystem for distinguishable and sequential detection of MnO4? and Cr2O72? based on the inner filter effect (IFE) between Gd2O3:Yb,Er upconversion nanospheres (UCNS) and 3,3’,5,5’-tetramethylbenzidine (TMB). The detection of MnO4? was realized by a stoichiometric oxidation reaction between TMB and Mn(VII), which resulted in quenching of the upconversion luminescence (UCL) by the blue product through IFE. The assay of Cr2O72?, in contrast, was based on the formation of complexes and the consumption of the oxidation product of the previous reaction. The sensing of MnO4? and Cr2O72? do not interfere with each other when Pb2+ was added as a masking agent. This provides a new strategy for sensitive and selective detection of MnO4? and Cr2O72?. The detection of MnO4? showed not only a low LOD of 0.243 μM but also high selectivity over other possible interfering ions. The sensitivity assay of MnO4? can be performed in the linear range of 1.85 to 69 μM. An excellent linear relationship was also found in the sensing of Cr2O72?, with a linear range of 18.3 to 250 μM and a LOD of 2.95 μM. The selectivity towards Cr2O72? was also proved to be good. Based on these properties, the UCNS–TMB nanoplatform is a potential chemosensor for both MnO4? and Cr2O72? ions in practical assays for waste water.
关键词： upconversion nanospheres,aqueous medium,UCNS/TMB nanosystem,Cr2O72?,MnO4?,TMB,fluorescent probe,inner filter effect,sequential sensing
更新于2025-11-14 17:03:37
-
Minimized reflectionless bandpass filter with four notches and low insertion loss
摘要： A size-minimized low-insertion-loss reflectionless bandpass filter with four notches is presented in this paper. The insertion loss of two quasi-elliptic-type filters is studied and optimized by a new approach based on cascade resonators branches. Parameters extraction procedure for the desired position of notches is illustrated. The inband performance, bandwidth and notch width are studied. This novel approach brings lower insertion loss. It can be extended to reflectionless bandpass filters with arbitrary number of notches. The size of filter is also minimized. This filter is designed, simulated, fabricated and measured. It is centered at 3.481 GHz with a 3-dB bandwidth of 276 MHz. The minimum measured in-band insertion loss, including the loss of SMA interface, is 1.239 dB. Four notches are located at 2.827, 3.238, 3.825 and 4.306 GHz, respectively. S11 of this filter is less than ?10 dB during 2–5 GHz.
关键词： microstrip filter,Bandpass filter,reflectionless filter,notches
更新于2025-09-23 15:23:52