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A highly efficiency fiber gas Raman amplifier based on hydrogen-filled hollow-core fiber is reported for the first time. Seeded by a 1.9 μm tunable THDFA, the maximum power conversion efficiency of 41% from 1064 nm pump to 1908 nm Stokes is obtained.
A C-band efficient fiber gas Raman laser amplifier is demonstrated for the first time in ethane-filled hollow-core fiber. A 1.5 μm tunable CW DFB laser is coupled into the ethane-filled hollow-core fiber as a seed, and amplified by stimulated Raman scattering of ethane. The Raman conversion efficiency from 1064 nm to 1553 nm is achieved to be 47.5%.
Nature Language Processing has been paid more attention recently. Traditional approaches for language model primarily rely on elaborately designed features and complicated natural language processing tools, which take a large amount of human effort and are prone to error propagation and data sparse problem. Deep neural network method has been shown to be able to learn implicit semantics of text without...
Anti-resonant hollow-core fibers (AR-HCFs) have attracted intensive attention. In order to realize low-loss coupling between anti-resonant hollow-core fibers and solid-core fibers, tapered solid-core fibers are injected into the hollow-core of AR-HCFs. For the ice-cream type anti-resonant hollow-core fibers whose mode field diameter are about 35μm, the coupling efficiency is over 85% when the tapered...
Here we demonstrate, to the best of our knowledge, a tunable 1.5 μm narrow linewidth fiber ring laser using a temperature tuning π-phase shifted fiber Bragg grating (π-PSFBG) for the first time. The π-PSFBG is employed as both a narrow band filter and a wavelength tuning component by a thermo electric cooler (TEC). The tuning range of the laser is 1.29 nm with the precision of 14 pm/°C, and the maximum...
Efficient 1.5 μm fiber gas Raman source has been demonstrated for the first time in methane-filled negative curvature hollow-core fiber (NC-HCF) with ice-cream-cone shaped cladding. With 4.5 bar methane gas filled, an 8.8 m long NC-HCF was pumped with a 1064 nm microchip laser, generating Stokes spectral line at 1543.7 nm. A maximum Raman conversion efficiency of about 57% has been achieved with 24...
In the template matching of finger vein recognition, the probe will be accepted if the number of its overlapped vein points with the enrolled user is larger than the predefined threshold. However, the acceptance may be false owing to ignoring the structure of the vein pattern. We find that local vein branches near the bifurcation point of vein pattern vary largely between the imposter images. So,...
In this paper, a novel framework for brain MRI threshold segmentation based on multi-objective model is proposed. Two classical techniques named Otsu's method (OTSU) and maximum entropy method (MET) are selected as the objective function based on their opposite characteristics when processing brain MRI with different levels of noise and bias field. The proposed method aims at finding trade-off solutions...
Finger vein pattern has become one of the most promising biometric identifiers. In this paper, we propose a robust finger vein verification method based on a personalized best patches map (PBPM). Firstly, some robust and discriminative visual words of finger vein are learned from traditional base feature such as local binary pattern (LBP). These visual words are named as finger vein textons (FVTs),...
Finger veins based biometrics, as a new approach to personal identification, has received much attention in recent years. The methods based on low level feature, for instance the gray, texture of finger vein, are the mainstream, but they are usually faced with many challenges, such as sensitivity to noise and low local consistency. In fact, finger vein recognition based on high level feature representation...
We evaluate two types of prosodic features utilizing automatically generated stress and tone labels for non-native read speech in terms of their applicability for automated speech scoring. oth types of features have not been used in the context of automated scoring of non-native read speech to date.
We demonstrate a novel method for low-loss splicing photonic crystal fibers (PCFs) and double cladding fibers (DCFs) by controlled hole collapse and tapering using a conventional fusion splicer. Through controlled hole collapse, two center rings of holes were collapsed to expand the core of the PCF, while the cladding diameter of the PCF was almostly not changed. The mode field diameter (MFD) and...
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