Browsing by Author "Wang, Hsien-Yi"

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Direct observation of dynamic thermal lensing in nanoscale surfaces/interfaces of end-pumped Nd:YVO4 laser
(2020-05-26)
Lin, Shou-Tai
;
Hung, Wei-Kuo
;
Zhuo, Guan-Yu
;
Wang, Hsien-Yi
;
Chan, Ming-Che
This work describes non-invasive observations of dynamic thermal lensing in an end-pumped Nd:YVO4 laser. Measurements were obtained with a nanoscale optical ruler created using chromatic aberrations, pinholes, dispersive gratings, and position-sensitive detectors. This study reports on variations in thermally induced oscillations and on underdamping behavior in the regime of high pump power. Dynamic data related to the thermal behavior can be used to study the balance between driving forces (pumping and thermal stresses) and damping losses (cooling and output coupling). The non-invasive nature of the proposed scheme along with its sub-100-nm axial resolution, sub-millisecond time resolution, and simple configuration makes it widely applicable for studying heat-related phenomena within laser crystals. The preliminary results show that such non-invasive methods could be used to detect thermally induced nanoscale deformations in integrated circuits, high-power optoelectronic devices, and optical devices with high-power illumination.
In situ high-resolution thermal microscopy on integrated circuits
(2017-09-04)
Zhuo, Guan-Yu
;
Su, Hai-Ching
;
Wang, Hsien-Yi
;
Chan, Ming-Che
;
光電系統研究所
The miniaturization of metal tracks in integrated circuits (ICs) can cause abnormal heat dissipation, resulting in electrostatic discharge, overvoltage breakdown, and other unwanted issues. Unfortunately, locating areas of abnormal heat dissipation is limited either by the spatial resolution or imaging acquisition speed of current thermal analytical techniques. A rapid, non-contact approach to the thermal imaging of ICs with sub-mu m resolution could help to alleviate this issue. In this work, based on the intensity of the temperature-dependent two-photon fluorescence (TPF) of Rhodamine 6G (R6G) material, we developed a novel fast and non-invasive thermal microscopy with a sub-mu m resolution. Its application to the location of hotspots that may evolve into thermally induced defects in ICs was also demonstrated. To the best of our knowledge, this is the first study to present highresolution 2D thermal microscopic images of ICs, showing the generation, propagation, and distribution of heat during its operation. According to the demonstrated results, this scheme has considerable potential for future in situ hotspot analysis during the optimization stage of IC development. (C) 2017 Optical Society \of America
Mechanical Scan-Free Confocal Microscope by a Broadband Source and Two Balanced Wavelength-to-Space Transformations
(2015-02-01)
Wang, Hsien-Yi
;
Lin, Bor-Shyh
;
Lou, Chien-Ya
;
Chan, Ming-Che
;
光電學院
A new approach for performing confocal microscopy without no mechanical scanners was reported by a broadband light source, two similar 2-D wavelength-dispersive optical elements, and an uncooled charge-coupled device (CCD). In the new approach, 2-D sample structures were simultaneously and instantly mapped into the CCD by performing two balanced wavelength-to-space transformations and one spaceto- wavelength transformation. Compared with a traditional mechanical-scanner-based confocal microscope, no mechanical scanners or additional post dataprocessing were required in this new approach. The sectioned images are directly shown in the CCD. The demonstrated balanced wavelength-encoded confocal microscope has a simple configuration and shows great potential for high imaging speed. It has the advantage of miniaturized packaging and other applications outside of the laboratory as well.
Nonlinear Light Microscopy by a 1.2-mu m Fiber-Laser-Based Femtosecond Dispersive Wave Source
(2015-06-01)
Wang, Hsien-Yi
;
Huang, Shiuan-Wen
;
Li, Dean-Ru
;
Lin, Bor-Shyh
;
Chan, Ming-Che
A fiber-laser-based femtosecond dispersive wave laser source, operated within the 1.2-to 1.3-mu m bio-penetration wavelength window, and its application on nonlinear light microscopy were both demonstrated in this paper. This portable 1.2-mu m femtosecond fiber-optic source was composed of an all-fiber 1.55-mu m mode-locked erbium-doped fiber laser as the excitation source and a nonlinear fiber as a frequency up converter. The 1.2-mu m femtosecond radiations with an up to a 55-mW output power and a 125-fs pulsewidth were experimentally demonstrated. By the fiber-based 1.2-mu m femtosecond dispersive wave source, nonlinear laser scanning microscopy, including two-photon fluorescence and second-harmonic generation microscopy, was also performed within the 1.2-to 1.3-mu m bio-penetration window in this report. The fiber-based 1.2-mu m femtosecond light source, with a simple system configuration, turn-key operation, and a miniaturized package, shows great potential for nonlinear light microscopy and other related applications outside of the laboratory.
Novel Noninvasive Approach for Detecting Arteriovenous Fistula Stenosis
(2014-06-01)
Wang, Hsien-Yi
;
Wu, Cho-Han
;
Chen, Chien-Yue
;
Lin, Bor-Shyh
;
影像與生醫光電研究所
Hemodialysis is the most common treatment for patients with end-stage renal disease. For hemodialysis, consistently functional vascular access must be surgically created with an anastomosis of artery and vein, referred to as an arteriovenous fistula (AVF). However, AVF dysfunction may occur over time. Angiography and Doppler ultrasound are usually used to detect the flow or the diameter of the AVF. But they require well-trained operators and are expensive, and even angiography is invasive. In this study, a noninvasive approach based on stethoscope auscultation for monitoring AVF stenosis was proposed. Here, a wireless blood flow sound recorder was designed to record blood flow sounds wirelessly. In order to effectively extract the varying feature of blood flow sounds for AVF stenosis, the 2-D feature pattern built from S-transform was also proposed as the feature in the AVF stenosis detecting algorithm. Different from other frequency-related coefficients, the feature pattern can contain the information of blood flow sounds in time and frequency domains simultaneously. Preliminary findings showed that the proposed approach can provide high-quality estimation of AVF stenosis (positive predictive value=87.84% and sensitivity = 89.24%).
Wave-vector-encoded nonlinear endomicroscopy
(2020-07-01)
Zhuo, Guan-Yu
;
Tsai, Po-Lin
;
Wang, Hsien-Yi
;
Chan, Ming-Che
;
光電學院
Based on a rigid square fiber for wave vector delivery, we present a novel (to the best of our knowledge) wave-vector-encoded nonlinear-optical endomicroscopy (WENE). WENE overcomes three tangled issues, including femtosecond pulse broadening induced signal degradation, complexity of packaging miniaturized scanners in the distal end, and pixel-like images, which cannot be fully addressed by current distal scanning nonlinear endomicroscopy (NE) or fiber-bundle-based proximal scanning NE. Due to the advantages of its simplicity in overall configuration and package in the distal end, the capability of addressing the issue of pulse broadening, and offering continuous wave vector delivery, the demonstrated WENE shows great promise for future basic research on biomedical processes and minimally invasive utilization for clinical diagnosis. (C) 2020 Optical Society of America
Widely wavelength tunable fast intensity-modulated light source for biophotonic applications
(2017-07-15)
Huang, Tzu-Feng
;
Tseng, Sheng-Hao
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Wang, Hsien-Yi
;
Chan, Ming-Che
;
光電學院
High modulation depth, fast (megahertz to gigahertz), intensity-modulated light sources of various wavelengths within the 0.7-1.35 mu m bio-penetration window are highly desirable for many biophotonic diagnosis systems. In this Letter, we present a novel scheme of a wavelength tunable, ultra-broadband light source which simply consists of a pump laser, a nonlinear fiber, and demodulation circuits. The working wavelength range of the light source is from 0.7 to 1.35 mu m which covers a vast part of the bio-penetration window, and its modulation frequencies extends from tens of megahertz to gigahertz. The performances of the proposed light source in either working wavelength range or modulation frequency bandwidth are much superior to any typical laser diodes or solid state lasers currently employed in the frequency-domain or other biophotonic utilization. The wide applicability of this novel light source in diverse biophotonic applications can be observed from our carefully designed diffused optical spectroscopy phantom measurement. (C) 2017 Optical Society of America