Prof. Fu-Jen Kao Profile

Prof. Fu-Jen Kao

Distinguished Professor at National Yang Ming Univ

SPIE Involvement:

Conference Program Committee | Author

Publications (45)

SPIE Journal Paper | 13 March 2020

Spontaneous loss versus stimulation gain in pump-probe microscopy: a proof of concept demonstration

Subir Das, Khalil Ur Rehman, Guan-Yu Zhuo, Fu-Jen Kao

JBO Vol. 25 Issue 03

KEYWORDS: Laser beam diagnostics, Seaborgium, Signal detection, Microscopy, Luminescence, Signal to noise ratio, Modulation, Sensors, Stimulated emission depletion microscopy, Photodetectors

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Significance: The large background, narrow dynamic range, and detector saturation have been the common limiting factors in stimulated emission (SE)-based pump-probe microscopy, attributed to the very small signal overriding the very intense laser probe beam. To better differentiate the signal of interest from the background, lock-in detection is used to measure the fluorescence quenching, which is termed spontaneous loss (SL). The advantages are manifold. The spontaneous fluorescence signal can be well separated from both the pump and the probe beams with filters, thus eliminating the background, enlarging the dynamic range, and avoiding the saturation of the detector. Aim: We propose and demonstrate an integrated pump-probe microscopy technique based on lock-in detection for background removal and dynamic range enhancement through SL detection. Approach: The experimental setup is configured with a pulsed diode laser at a wavelength λpu = 635 nm, acting as a pump (excitation) and a mode-locked Ti:sapphire laser at a central wavelength λpr = 780 nm, serving as the probe beam (stimulation). Both pulse trains are temporally synchronized through high precision delay control by adjusting the length of the triggering cables. The pump and probe beams are alternatively modulated at different frequencies f1 and f2 to extract the stimulated gain (SG) and SL signal. Results: SG signal shows saturation due to the irradiation of the intense probe beam onto the photodetector. However, the detector saturation does not occur at high probe beam power for SL detection. The fluorescence lifetime images are acquired with reduced background. The theoretical signal-to-noise ratios for SG and SL are also estimated by photon statistics. Conclusion: We have confirmed that the detection of SL allows the elimination of the large background without photodetector saturation, which commonly exists in SG configuration. This modality would allow unprecedented manipulation and investigation of fluorophores in fluorescence imaging.

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Proceedings Article | 9 March 2020 Presentation

Synchronized subharmonic modulation in stimulated emission microscopy (Conference Presentation)

Fu-Jen Kao

Proc. SPIE. 11244, Multiphoton Microscopy in the Biomedical Sciences XX

KEYWORDS: Signal to noise ratio, Confocal microscopy, Modulation, Sensors, Microscopy, Luminescence, Image resolution, Laser beam diagnostics, Signal detection, Absorption

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Proceedings Article | 23 February 2018 Paper

Stimulated emission and spontaneous loss pump-probe microscopy for background removal

Subir Das, Bo-Wei Ho, Fu-Jen Kao

Proc. SPIE. 10498, Multiphoton Microscopy in the Biomedical Sciences XVIII

KEYWORDS: Signal to noise ratio, Multiphoton microscopy, Modulation, Microscopy, Semiconductor lasers

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Proceedings Article | 18 April 2017 Paper

Determination of three-dimensional molecular orientation of type-I collagen by circularly-polarized second harmonic generation imaging

Guan-Yu Zhuo, Wei-Han Hung, Fu-Jen Kao

Proc. SPIE. 10251, Biomedical Imaging and Sensing Conference

KEYWORDS: Second-harmonic generation, Biomedical optics, Polarization, Tissues, Skin, Microscopy, Molecules, Collagen, Harmonic generation, 3D image processing

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Proceedings Article | 9 March 2015 Paper

Optical coherence detection with stimulated emission: a feasibility study

Chun-hui Yu, Shen-Shou Chung, Wen-Chuan Kuo, Fu-Jen Kao

Proc. SPIE. 9330, Three-Dimensional and Multidimensional Microscopy: Image Acquisition and Processing XXII

KEYWORDS: Photodetectors, Mirrors, Light sources, Coherence (optics), Scattering, Optical coherence tomography, Luminescence, Interferometry, Laser beam diagnostics, Signal detection

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SPIE Journal Paper | 7 October 2014

Compact light-emitting diode lighting ring for video-assisted thoracic surgery

Ming-Kuan Lu, Feng-Chen Chang, Wen-Zhe Wang, Chih-Cheng Hsieh, Fu-Jen Kao

JBO Vol. 19 Issue 10

KEYWORDS: Light emitting diodes, LED lighting, Light sources and illumination, Surgery, Endoscopes, Light sources, Chest, Fiber couplers, Solids, Endoscopy

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Proceedings Article | 28 February 2014 Paper

In pixel analysis of molecular structure with Stokes vector resolved second harmonic generation microscopy

Nirmal Mazumder, Lu Yun Xiang, Jianjun Qiu, Fu-Jen Kao

Proc. SPIE. 8948, Multiphoton Microscopy in the Biomedical Sciences XIV

KEYWORDS: Photon counting, Second-harmonic generation, Polarization, Calibration, Microscopy, Molecules, Polarimetry, Collagen, Nonlinear optics, Harmonic generation

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Proceedings Article | 28 February 2014 Paper

Multiphoton microscopy for skin wound healing study in terms of cellular metabolism and collagen regeneration

Gitanjal Deka, Kazunori Okano, Wei-Wen Wu, Fu-Jen Kao

Proc. SPIE. 8948, Multiphoton Microscopy in the Biomedical Sciences XIV

KEYWORDS: Proteins, Second-harmonic generation, Wound healing, Multiphoton microscopy, Tissues, Skin, Collagen, Biopsy, Fluorescence lifetime imaging, Anisotropy

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Proceedings Article | 28 February 2014 Paper

Enhancing stimulated emission-based fluorescence detection with interferometric setup

Shen-Shou Max Chung, Jia-Hui Deng, Po-Lin Lin, Fu-Jen Kao

Proc. SPIE. 8948, Multiphoton Microscopy in the Biomedical Sciences XIV

KEYWORDS: Mirrors, Microscopy, Luminescence, Fluorescence spectroscopy, Interferometry, Fluorescence lifetime imaging, Picosecond phenomena, Laser beam diagnostics, Signal detection, Destructive interference

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SPIE Journal Paper | 24 January 2014

Special Section Guest Editorial: Advanced Biomedical Imaging and Sensing

Chi-Kuang Sun, Arthur Chiou, Fu-Jen Kao, Chien Chou, Chen-Yuan Dong

JBO Vol. 19 Issue 01

KEYWORDS: Biomedical optics, Biosensing, Photonics, Medicine, Raman spectroscopy, Sun, Physics, Molecular electronics, Molecular imaging, Yeast

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SPIE Journal Paper | 19 August 2013

Dynamic photopatterning of cells in situ by Q-switched neodymium-doped yttrium ortho-vanadate laser

Gitanjal Deka, Kazunori Okano, Fu-Jen Kao

JBO Vol. 19 Issue 01

KEYWORDS: Gold, Polymers, Laser engraving, Laser ablation, Coating, Q switched lasers, Transducers, Adhesives, Neodymium, Glasses

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Proceedings Article | 22 February 2013 Paper

Fluorescence lifetime imaging with pulsed diode laser enabled stimulated emission

Jianhong Ge, Yixin Wang, Cuifang Kuang, Shin-Shian Lee, Nirmal Mazumder, Fu-Jen Kao

Proc. SPIE. 8588, Multiphoton Microscopy in the Biomedical Sciences XIII

KEYWORDS: Light sources, Modulation, Polarization, Sensors, Luminescence, Photodiodes, Control systems, Semiconductor lasers, Objectives, Fluorescence lifetime imaging

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Proceedings Article | 22 February 2013 Paper

Imaging molecular structure with Stokes-polarimeter based second harmonic generation microscopy

Nirmal Mazumder, Jianjun Qiu, Chih-Wei Hu, Fu-Jen Kao

Proc. SPIE. 8588, Multiphoton Microscopy in the Biomedical Sciences XIII

KEYWORDS: Photon counting, Second-harmonic generation, Polarization, Microscopy, Molecules, Polarimetry, Collagen, Harmonic generation, Signal detection, Anisotropy

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SPIE Journal Paper | 18 December 2012

In vivo wound healing diagnosis with second harmonic and fluorescence lifetime imaging

Gitanjal Deka, Wei-Wen Wu, Fu-Jen Kao

JBO Vol. 18 Issue 06

KEYWORDS: Wound healing, Collagen, Skin, Second-harmonic generation, Fluorescence lifetime imaging, Tissues, In vivo imaging, Signal detection, Proteins, Microscopy

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SPIE Journal Paper | 21 May 2012

Metabolism of HeLa cells revealed through autofluorescence lifetime upon infection with enterohemorrhagic Escherichia coli

Tatyana Buryakina, Pin-Tzu Su, Wan-Jr Syu, C. Allen Chang, Hsui-Fang Fan, Fu-Jen Kao

JBO Vol. 17 Issue 10

KEYWORDS: Cell death, Luminescence, Fluorescence lifetime imaging, Mode conditioning cables, Picosecond phenomena, Proteins, Bacteria, Molecules, Acquisition tracking and pointing, Pathogens

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Proceedings Article | 13 February 2012 Paper

Stokes vector formalism based second harmonic generation microscopy

Jianjun Qiu, Nirmal Mazumder, Han-Ruei Tsai, Chih-Wei Hu, Fu-Jen Kao

Proc. SPIE. 8228, Single Molecule Spectroscopy and Superresolution Imaging V

KEYWORDS: Microscopes, Beam splitters, Second-harmonic generation, Biomedical optics, Polarization, Birefringence, Microscopy, Collagen, Laser scanners, Harmonic generation

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Proceedings Article | 9 February 2012 Paper

Long-distance fluorescence lifetime imaging with stimulated emission and electronic time delay

Po-Yen Lin, Shin-Shian Lee, Chia-Seng Chang, Fu-Jen Kao

Proc. SPIE. 8226, Multiphoton Microscopy in the Biomedical Sciences XII

KEYWORDS: Imaging systems, Luminescence, Photons, Molecules, Fluorescence spectroscopy, Photodiodes, Temporal resolution, Spatial coherence, Fluorescence lifetime imaging, Signal detection

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SPIE Journal Paper | 6 February 2012

Long-distance fluorescence lifetime imaging using stimulated emission

Thilo Dellwig, Po-Yen Lin, Fu-Jen Kao

JBO Vol. 17 Issue 1

KEYWORDS: Luminescence, Fluorescence lifetime imaging, Biomedical optics, Light sources, Indocyanine green, Molecules, Sensors, Modulation, Rhodamine, Signal to noise ratio

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SPIE Journal Paper | 1 February 2011

Forward-collected simultaneous fluorescence lifetime imaging and coherent anti-Stokes Raman scattering microscopy

Aaron Slepkov, Andrew Ridsdale, Adrian Pegoraro, Douglas Moffatt, John Pezacki, Albert Stolow, Huei-Ning Wan, Ming-Hao Wang, Fu-Jen Kao

JBO Vol. 16 Issue 02

KEYWORDS: Fluorescence lifetime imaging, Microscopes, Multimode fibers, Microscopy, Picosecond phenomena, CARS tomography, Sensors, Fiber couplers, Signal detection, Photons

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Proceedings Article | 18 August 2010 Paper

Assessment of ESD robustness in high power light emitting diodes

Shih-Chun Yang, Pang Lin, Han-Kuei Fu, Chien-Ping Wang, Tzung-Te Chen, An-Tse Lee, Sheng-Bang Huang, Pei-Ting Chou, Wei Wang, Fu-Jen Kao

Proc. SPIE. 7784, Tenth International Conference on Solid State Lighting

KEYWORDS: Electronics, Light emitting diodes, Electroluminescence, Scanning electron microscopy, Transmission electron microscopy, Gallium nitride, Sapphire, Diodes, Failure analysis, Instrument modeling

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Proceedings Article | 12 February 2010 Paper

Smart windows with functions of reflective display and indoor temperature-control

I-Hui Lee, Yu-Ching Chao, Chih-Cheng Hsu, Liang-Chao Chang, Tien-Lung Chiu, Jiunn-Yih Lee, Fu-Jen Kao, Chih-Kung Lee, Jiun-Haw Lee

Proc. SPIE. 7618, Emerging Liquid Crystal Technologies V

KEYWORDS: Refractive index, Visible radiation, Scattering, Polymers, Light scattering, Reflectivity, Liquid crystals, Transmittance, Infrared radiation, Reflective displays

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SPIE Journal Paper | 1 January 2010

Fluorescence lifetime dynamics of enhanced green fluorescent protein in protein aggregates with expanded polyglutamine

Vladimir Ghukasyan, Chih-Chun Hsu, Chia-Rung Liu, Fu-Jen Kao, Tzhu-Hao Cheng

JBO Vol. 15 Issue 01

KEYWORDS: Luminescence, Proteins, Green fluorescent protein, Molecules, Refractive index, Anisotropy, Fluorescence resonance energy transfer, Molecular aggregates, Fluorescence lifetime imaging, Yeast

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Proceedings Article | 25 February 2009 Paper

Fluorescence lifetime dynamics of eGFP in protein aggregates with expanded polyQ

Vladimir Ghukasyan, Chih-Chun Hsu, Chia-Rung Liu, Fu-Jen Kao, Tzu-Hao Cheng

Proc. SPIE. 7183, Multiphoton Microscopy in the Biomedical Sciences IX

KEYWORDS: Refractive index, Proteins, Green fluorescent protein, Data modeling, Luminescence, Chromophores, Cell death, Yeast, Picosecond phenomena, Absorption

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Proceedings Article | 13 February 2009 Paper

Imaging dental sections with polarization-resolved SHG and time-resolved autofluorescence

Jun Huang Chen, Po-Yen Lin, Stephen C. Hsu, Fu-Jen Kao

Proc. SPIE. 7183, Multiphoton Microscopy in the Biomedical Sciences IX

KEYWORDS: Second-harmonic generation, Polarization, Teeth, Tissues, Microscopy, Luminescence, Crystals, Collagen, Sapphire lasers, Fluorescence lifetime imaging

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Proceedings Article | 13 February 2009 Paper

Metabolic mapping of cell culture growth by NADH fluorescence lifetime imaging

Vladimir Ghukasyan, Tatyana Buryakina, Fu-Jen Kao

Proc. SPIE. 7183, Multiphoton Microscopy in the Biomedical Sciences IX

KEYWORDS: Optical filters, Data modeling, Microscopy, Luminescence, Molecules, Diffusion, Fluorescence lifetime imaging, Picosecond phenomena, Mode conditioning cables, Cellular energetics

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SPIE Journal Paper | 1 September 2008

Reduced nicotinamide adenine dinucleotide fluorescence lifetime separates human mesenchymal stem cells from differentiated progenies

Han-Wen Guo, Chien-Tsun Chen, Yau-Huei Wei, Oscar Lee, Vladimir Ghukasyan, Fu-Jen Kao, Hsing-Wen Wang

JBO Vol. 13 Issue 05

KEYWORDS: Luminescence, Stem cells, Picosecond phenomena, Mode conditioning cables, Acquisition tracking and pointing, In vivo imaging, Fluorescence lifetime imaging, Solids, Biomedical optics, Molecular biology

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SPIE Journal Paper | 1 September 2008

Differentiation of apoptosis from necrosis by dynamic changes of reduced nicotinamide adenine dinucleotide fluorescence lifetime in live cells

Hsing-Wen Wang, Vladimir Ghukasyan, Chien-Tsun Chen, Yau-Huei Wei, Han-Wen Guo, Jia-Sin Yu, Fu-Jen Kao

JBO Vol. 13 Issue 05

KEYWORDS: Cell death, Luminescence, Picosecond phenomena, Control systems, Fluorescence lifetime imaging, Photon counting, Data acquisition, Data modeling, Acquisition tracking and pointing, Ultrasonography

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Proceedings Article | 2 May 2008 Paper

Biophotonic applications of optical communication devices

Gerd Keiser, Fu-Jen Kao

Proc. SPIE. 6991, Biophotonics: Photonic Solutions for Better Health Care

KEYWORDS: Optical fibers, Optical components, Thin films, Optical filters, Biomedical optics, Waveguides, Fiber Bragg gratings, Ultraviolet radiation, Telecommunications, Tissue optics

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Proceedings Article | 15 February 2008 Paper

Characterization of the NADH lifetime at different cell densities in a culture

Vladimir Ghukasyan, Fu-Jen Kao

Proc. SPIE. 6860, Multiphoton Microscopy in the Biomedical Sciences VIII

KEYWORDS: Microscopes, Photon counting, Proteins, Data modeling, Luminescence, Molecules, Diagnostics, Fluorescence lifetime imaging, Picosecond phenomena, Mode conditioning cables

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SPIE Journal Paper | 1 March 2007

Application of fluorescence resonance energy transfer resolved by fluorescence lifetime imaging microscopy for the detection of enterovirus 71 infection in cells

Vladimir Gukassyan, Yueh-Ying Hsu, Szu-Hao Kung, Fu-Jen Kao

JBO Vol. 12 Issue 02

KEYWORDS: Fluorescence resonance energy transfer, Fluorescence lifetime imaging, Microscopy, Cell death, Luminescence, Proteins, Molecules, Data modeling, RGB color model, Green fluorescent protein

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Proceedings Article | 7 December 2006 Paper

Cellular vitality of PC12 cells revealed through auto-fluorescence induced by two-photon excitation

Elena Perevedentseva, Artashes Karmenyan, Fu-Jen Kao

Proc. SPIE. 5973, Current Research on Laser Use in Oncology: 2000-2004

KEYWORDS: Near infrared, Femtosecond phenomena, Spectroscopy, Microscopy, Luminescence, Fluorescence spectroscopy, Laser irradiation, Laser scanners, Optical tweezers, Mode conditioning cables

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Proceedings Article | 18 January 2005 Paper

Harmonic generation microscopy of dental sections

Fu-Jen Kao, Chin-Ying Hsu

Proc. SPIE. 5630, Optics in Health Care and Biomedical Optics: Diagnostics and Treatment II

KEYWORDS: Second-harmonic generation, Optical parametric oscillators, Biomedical optics, Teeth, Microscopy, Luminescence, Collagen, Phase matching, Sapphire lasers, Harmonic generation

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Proceedings Article | 11 January 2005 Paper

Laser scanning microscopy as a versatile platform: imaging based on nonlinear and ultrafast effects

Fu-Jen Kao

Proc. SPIE. 5642, Information Optics and Photonics Technology

KEYWORDS: Confocal microscopy, Second-harmonic generation, Modulation, Microscopy, Collagen, Laser scanners, Signal processing, Ultrafast lasers, Harmonic generation, Signal detection

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Proceedings Article | 21 June 2004 Paper

Use of optical parametric oscillator in scanning optical microscopy

Fu-Jen Kao

Proc. SPIE. 5323, Multiphoton Microscopy in the Biomedical Sciences IV

KEYWORDS: Second-harmonic generation, Optical parametric oscillators, Ultraviolet radiation, Microscopy, Luminescence, Optical microscopy, Collagen, Phase matching, Sapphire lasers, Harmonic generation

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Proceedings Article | 16 June 2004 Paper

Optical biosensor based on localized surface plasmon resonance with high spatial resolution

Xin Hong, Fu-Jen Kao

Proc. SPIE. 5327, Plasmonics in Biology and Medicine

KEYWORDS: Gold, Optical fibers, Light sources, Surface plasmons, Biosensing, Sensors, Nanoparticles, Objectives, Spatial resolution, Absorption

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Proceedings Article | 8 June 2004 Paper

Optical beam induced current microscopy at DC and radio frequency

Fu-Jen Kao

Proc. SPIE. 5353, Semiconductor Photodetectors

KEYWORDS: Semiconductors, Radio optics, Electrodes, Mode locking, Diffusion, Photodiodes, Spatial resolution, Active optics, Pulsed laser operation, Near field optics

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Proceedings Article | 4 December 2003 Paper

The use of advanced light source and signal processing in scanning optical microscopy

Fu-Jen Kao

Proc. SPIE. 5255, Biomolecular Photonics and Multidimensional Microscopy

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Proceedings Article | 24 April 2001 Paper

Nonlinear multimodality spectromicroscopy: multiphoton fluorescence, SHG, and THG of biological specimen

Ping Cheng, Chi-Kuang Sun, Bai-Ling Lin, Fu-Jen Kao, Shi-Wei Chu

Proc. SPIE. 4262, Multiphoton Microscopy in the Biomedical Sciences

KEYWORDS: Visible radiation, Second-harmonic generation, Multiphoton microscopy, Signal attenuation, Microscopy, Luminescence, Nonlinear optics, Sapphire lasers, Signal detection, Multiphoton fluorescence microscopy

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