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  • 1
    Online Resource
    Online Resource
    In-Situ Depth Measurement of Laser Micromachining
    MDPI AG ; 2021
    In:  Photonics Vol. 8, No. 11 ( 2021-11-04), p. 493-
    Details
    In: Photonics, MDPI AG, Vol. 8, No. 11 ( 2021-11-04), p. 493-
    Abstract: Precision laser micromachining plays an important role in the biomedical, electronics, and material processing industries. During laser drilling, precision depth detection with micrometer-level resolution is required, particularly with blind-hole or heterogeneous structures. We present an optical detection system utilizing an optical confocal structure, experimentally confirmed to achieve a 〉 95% accuracy for micron-diameter holes that are tens-of-microns deep. This system can be easily integrated into commercial laser micromachining processes, and can be employed in laser drilling and three-dimensional active-feedback laser printing.
    Type of Medium: Online Resource
    ISSN: 2304-6732
    URL: Article
    DOI: 10.3390/photonics8110493
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2770002-1
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  • 2
    Online Resource
    Online Resource
    High Sensitivity Fiber Refractive Index Sensors Based on Asymmetric Supermodes Interference in Tapered Four Core Fiber
    MDPI AG ; 2022
    In:  Photonics Vol. 9, No. 1 ( 2022-01-14), p. 45-
    Details
    In: Photonics, MDPI AG, Vol. 9, No. 1 ( 2022-01-14), p. 45-
    Abstract: We demonstrate high sensitivity fiber refractive index (RI) sensor based on asymmetric supermode interferences in tapered four core fiber (TFCF). To make TFCF-based RI sensors, the whitelight was launched into any one of the cores to define the excitation orientation and is called a vertex-core excitation scheme. When the four-core fiber (FCF) was gradually tapered, the four cores gathered closer and closer. Originally, the power coupling occurred between its two neighboring cores first and these three cores are grouped to produce supermodes. Subsequently, the fourth diagonal core enters the evanescent field overlapping region to excite asymmetric supermodes interferences. The output spectral responses of the two cores next to the excitation core are mutually in phase whereas the spectral responses of the diagonal core are in phase and out of phase to that of the excitation core at the shorter and longer wavelengths, respectively. Due to the lowest limitation of the available refractive index of liquids, the best sensitivity can be achieved when the tapered diameter is 10 μm and the best RI sensitivity S is 3249 nm/RIU over the indices ranging from 1.41–1.42. This is several times higher than that at other RI ranges due to the asymmetric supermodes.
    Type of Medium: Online Resource
    ISSN: 2304-6732
    URL: Article
    DOI: 10.3390/photonics9010045
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
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  • 3
    Online Resource
    Online Resource
    Micro-Tapered Fiber Few-Mode Interferometers Incorporated by Molecule Self-Assembly Fiber Grating for Temperature Sensing Applications
    MDPI AG ; 2022
    In:  Photonics Vol. 9, No. 2 ( 2022-02-07), p. 96-
    Details
    In: Photonics, MDPI AG, Vol. 9, No. 2 ( 2022-02-07), p. 96-
    Abstract: We demonstrate fiber few-mode interferometers based on a self-assembly surface corrugated grating using charged nano-particles. Initially, an abrupt taper (AT) was first created using a micro flame. The AT was then further outwardly stretched to make an elongated uniformed taper until the tapered diameter achieved a micron scale. The high order core modes (HOCMs) were excited at the AT and the optical path difference (OPD) among the modes was enlarged through the uniformed taper to achieve the few-mode interference effects seen. However, to significantly enhance the interference effects with higher extinction ratios (ER) over such a short length of interferometer, an external assisted grating was made using charged nanoparticles to form surface corrugated grating with a period, Λ, of approximately 14 μm. This intermediate period of the fiber grating was helpful in scattering and attenuating some unwanted high-order modes to change the optical characteristics of the few-mode interferometer (FMI). This FMI with a self-assembly fiber grating (SAFG) was further used to make fiber temperature sensors, with a maximum resonant wavelength shift of 4.6 nm, over a temperature range from 20–60 °C. The temperature sensitivity achieved was 112.6 pm/°C and the coefficient of determination, R2, was as high as 0.99, which revealed the high linearity of the results.
    Type of Medium: Online Resource
    ISSN: 2304-6732
    URL: Article
    DOI: 10.3390/photonics9020096
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
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  • 4
    Online Resource
    Online Resource
    High Sensitivity Strain Sensors Using Four-Core Fibers through a Corner-Core Excitation
    MDPI AG ; 2022
    In:  Micromachines Vol. 13, No. 3 ( 2022-03-11), p. 431-
    Details
    In: Micromachines, MDPI AG, Vol. 13, No. 3 ( 2022-03-11), p. 431-
    Abstract: A weakly-coupled multicore fiber can generate supermodes when the multi-cores are closer to enter the evanescent power coupling region. The high sensitivity strain sensors using tapered four-core fibers (FCFs) were demonstrated. The fan-in and fan-out couplers were used to carry out light coupling between singlemode fibers and the individual core of the FCFs. A broadband lightsource from superlumminescent diodes (SLDs) was launched into one of the four cores arranged in a rectangular configuration. When the FCF was substantially tapered, the asymmetric supermodes were produced to generate interferences through this corner-core excitation scheme. During tapering, the supermodes were excited based on a tri-core structure initially and then transited to a rectangular quadruple-core structure gradually to reach the sensitivity of 185.18 pm/μԑ under a tapered diameter of 3 μm. The asymmetric evanescent wave distribution due to the corner-core excitation scheme is helpful to increase the optical path difference (OPD) between supermodes for improving the strain sensitivity.
    Type of Medium: Online Resource
    ISSN: 2072-666X
    URL: Article
    DOI: 10.3390/mi13030431
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2620864-7
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  • 5
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    Online Resource
    Design of Fiber-Tip Refractive Index Sensor Based on Resonant Waveguide Grating with Enhanced Peak Intensity
    MDPI AG ; 2021
    In:  Applied Sciences Vol. 11, No. 15 ( 2021-07-22), p. 6737-
    Details
    In: Applied Sciences, MDPI AG, Vol. 11, No. 15 ( 2021-07-22), p. 6737-
    Abstract: Resonant waveguide gratings (RWG) are widely used as on-chip refractometers due to their relatively high sensitivity to ambient refractive index changes, their possibility of parallel high-throughput detection and their easy fabrication. In the last two decades, efforts have been made to integrate RWG sensors onto fiber facets, although practical application is still hindered by the limited resonant peak intensity caused by the low coupling efficiency between the reflected beam and the fiber mode. In this work, we propose a new compact RWG fiber-optic sensor with an additional Fabry-Pérot cavity, which is directly integrated onto the tip of a single-mode fiber. By introducing such a resonant structure, a strongly enhanced peak reflectance and improved figure of merit are achieved, while, at the same time, the grating size can be greatly reduced, thus allowing for spatial multiplexing of many sensors on a tip of a single multi-core fiber. This paves the way for the development of probe-like reflective fiber-tip RWG sensors, which are of great interest for multi-channel biochemical sensing and for real-time medical diagnostics.
    Type of Medium: Online Resource
    ISSN: 2076-3417
    URL: Article
    DOI: 10.3390/app11156737
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2704225-X
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  • 6
    Online Resource
    Online Resource
    High Sensitivity Fiber Interferometric Strain Sensors Based on Elongated Fiber Abrupt Tapers
    MDPI AG ; 2022
    In:  Micromachines Vol. 13, No. 7 ( 2022-06-27), p. 1015-
    Details
    In: Micromachines, MDPI AG, Vol. 13, No. 7 ( 2022-06-27), p. 1015-
    Abstract: We demonstrate high-sensitivity fiber strain sensors based on an elongated abrupt taper. The fiber abrupt taper, with a tapered diameter ranging from 40–60 μm, was made by using a hydrogen microflame to break the waveguide adiabaticity so as to convert the fundamental mode into cladding modes. The abrupt taper was further uniformly tapered by using a normal moving flame with a torch diameter of 7 mm to elongate the tapered region until the tapered diameter was down to 2.5–5 μm. The excited high-order modes were confined to propagate along the cladding and then recombined at the rear edge of the fiber taper to produce interferences with extinction ratios of up to 16 dB. The tapered region was pulled outwardly to change the optical path difference (OPD) between modes to measure the tensile strain with all the interfering wavelengths blue-shifted. The measured best strain sensitivity was 116.21 pm/με and the coefficient of determination R2 of linear fitting exhibits high linearity. This strain sensor based on elongated abrupt taper is several times higher than that of most of the fiber strain sensors ever reported.
    Type of Medium: Online Resource
    ISSN: 2072-666X
    URL: Article
    DOI: 10.3390/mi13071015
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
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  • 7
    Online Resource
    Online Resource
    Multicore Fiber Bending Sensors with High Sensitivity Based on Asymmetric Excitation Scheme
    MDPI AG ; 2022
    In:  Sensors Vol. 22, No. 15 ( 2022-07-29), p. 5698-
    Details
    In: Sensors, MDPI AG, Vol. 22, No. 15 ( 2022-07-29), p. 5698-
    Abstract: Bending sensing was realized by constructing a tapered four-core optical fiber (TFCF) sensor. The four-core fiber (FCF) between the fan-in and fan-out couplers was tapered and the diameter became smaller, so that the distance between the four cores arranged in a square became gradually smaller to produce supermodes. The two ends of the TFCF were respectively connected to the fan-in and fan-out couplers so that the individual cores in the FCF could link to the separate single-mode fibers. A broadband light source (superluminescent diodes (SLD)) spanning 1250–1650 nm was injected into any one of the four cores, and the orientation was thus determined. In the tapering process, the remaining three cores gradually approached the excitation core in space to excite several supermodes based on the tri-core structure first, and then transited to the quadruple-core structure. The field distributions of the excited supermodes were asymmetric due to the corner-core excitation scheme, and the interference thus resulted in a higher measurement sensitivity. When the diameter of the TFCF was 7.5 μm and the tapered length was 2.21 mm, the sensitivity of the bending sensor could reach 16.12 nm/m−1.
    Type of Medium: Online Resource
    ISSN: 1424-8220
    URL: Article
    DOI: 10.3390/s22155698
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2052857-7
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  • 8
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    Online Resource
    Output Pulse Characteristics of a Mamyshev Fiber Oscillator
    MDPI AG ; 2021
    In:  Photonics Vol. 8, No. 12 ( 2021-12-18), p. 590-
    Details
    In: Photonics, MDPI AG, Vol. 8, No. 12 ( 2021-12-18), p. 590-
    Abstract: The dependence of the output pulse characteristics of a Mamyshev fiber oscillator on cavity parameters is investigated in detail. We analyze the change in pulse spectrum bandwidth, pulse duration, dechirped pulse duration and chirp with the change in fiber group velocity dispersion, fiber nonlinearity, gain, and filters by putting forward a numerical model. In particular, as one of the most important components, the effect of filters bandwidth and the central wavelength interval between them is discussed. The passive fibers are classified into two kinds according to their locations in the cavity, which are the one before the gain fiber and the one after the gain fiber. Numerical simulation results show that a wide spectrum can be obtained by increasing the nonlinearity of the second passive fiber, while the change in nonlinearity of the first passive fiber has a weak effect on spectrum broadening. A wide spectrum could also be obtained by increasing the nonlinearity or the small-signal gain coefficient of the gain fiber. A Yb-doped Mamyshev fiber oscillator is demonstrated. The results show the increase in pump power, which agrees reasonably well with the numerical simulation results.
    Type of Medium: Online Resource
    ISSN: 2304-6732
    URL: Article
    DOI: 10.3390/photonics8120590
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
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  • 9
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    Online Resource
    Therapeutic Zfra4-10 or WWOX7-21 Peptide Induces Complex Formation of WWOX with Selective Protein Targets in Organs that Leads to Cancer Suppression and Spleen Cytotoxic Memory Z Cell Activation In Vivo
    MDPI AG ; 2020
    In:  Cancers Vol. 12, No. 8 ( 2020-08-05), p. 2189-
    Details
    In: Cancers, MDPI AG, Vol. 12, No. 8 ( 2020-08-05), p. 2189-
    Abstract: Synthetic Zfra4-10 and WWOX7-21 peptides strongly suppress cancer growth in vivo. Hypothetically, Zfra4-10 binds to the membrane Hyal-2 of spleen Z cells and activates the Hyal-2/WWOX/SMAD4 signaling for cytotoxic Z cell activation to kill cancer cells. Stimulation of membrane WWOX in the signaling complex by a WWOX epitope peptide, WWOX7-21, is likely to activate the signaling. Here, mice receiving Zfra4-10 or WWOX7-21 peptide alone exhibited an increased binding of endogenous tumor suppressor WWOX with ERK, C1qBP, NF-κB, Iba1, p21, CD133, JNK1, COX2, Oct4, and GFAP in the spleen, brain, and/or lung which led to cancer suppression. However, when in combination, Zfra4-10 and WWOX7-21 reduced the binding of WWOX with target proteins and allowed tumor growth in vivo. In addition to Zfra4-10 and WWOX7-21 peptides, stimulating the membrane Hyal-2/WWOX complex with Hyal-2 antibody and sonicated hyaluronan (HAson) induced Z cell activation for killing cancer cells in vivo and in vitro. Mechanistically, Zfra4-10 binds to membrane Hyal-2, induces dephosphorylation of WWOX at pY33 and pY61, and drives Z cell activation for the anticancer response. Thus, Zfra4-10 and WWOX7-21 peptides, HAson, and the Hyal-2 antibody are of therapeutic potential for cancer suppression.
    Type of Medium: Online Resource
    ISSN: 2072-6694
    URL: Article
    DOI: 10.3390/cancers12082189
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
    detail.hit.zdb_id: 2527080-1
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  • 10
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    Online Resource
    Predictive Effects of Inflammatory Scores in Patients with BCLC 0-A Hepatocellular Carcinoma after Hepatectomy
    MDPI AG ; 2019
    In:  Journal of Clinical Medicine Vol. 8, No. 10 ( 2019-10-14), p. 1676-
    Details
    In: Journal of Clinical Medicine, MDPI AG, Vol. 8, No. 10 ( 2019-10-14), p. 1676-
    Abstract: Background: Inflammatory markers are regarded as prognostic factors of the outcomes of hepatocellular carcinoma (HCC). Examples include the neutrophil-to-lymphocyte ratio (NLR); platelet to lymphocyte ratio (PLR); the albumin and lymphocyte counts used in the prognostic nutritional index (PNI); and the neutrophil, lymphocyte, and platelet counts used in the systemic immune-inflammation index (SII). This study evaluates the effects of PNI, NLR, PLR, and SII to predict recurrence and survival in patients with Barcelona Clinic Liver Cancer (BCLC) stages 0-A of HCC after hepatectomy. Methods: This retrospective study was conducted at Kaohsiung Chung-Gung Memorial Hospital, Taiwan. The study enrolled 891 patients (77.9% males; mean age 58.53 ± 11.60 years) with BCLC stage 0/A HCC undergoing hepatectomy between 2001 and 2016. PNI, NLR, PLR and SII were measured before hepatectomy. Results: High NLR ( 〉 1.8) was adversely associated with overall survival (p = 0.032). Low PNI (≤45) was adversely associated with overall survival and disease-free survival (p 〈 0.001). Low SII (≤45) also had an adverse association with overall survival (p = 0.008) and disease-free survival (p 〈 0.001). Diabetes mellitus, cirrhosis, microvascular invasion, low PNI (≤45), and low SII (≤160) were independently associated with poor overall survival in a multivariate analysis. HCV infection, diabetes mellitus, cirrhosis, microvascular invasion, low PNI, and low SII were independent prognostic factors of recurrent HCC. The combined use of PNI and SII provided improved prognostic information. Conclusions: Low PNI and low SII are significantly poor prognostic factors for overall survival and recurrence in patients with BCLC 0-A hepatocellular carcinoma after hepatectomy.
    Type of Medium: Online Resource
    ISSN: 2077-0383
    URL: Article
    DOI: 10.3390/jcm8101676
    Language: English
    Publisher: MDPI AG
    Publication Date: 2019
    detail.hit.zdb_id: 2662592-1
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