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Research Interests: Mechanical Engineering, Applied Mathematics, Physics, Materials Science, Optics, and 14 moreLaser, Spectroscopy, Medicine, Solid State Laser, Doping, Iodine, Applied Optics, Optical physics, Femtosecond, Metrologia, Optical Frequency Comb, Electrical And Electronic Engineering, Hyperfine Structure, and Muonium
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Optical comb spacing of 2.5 nm was generated from fused-quartz micro-resonator with Q ~ 107. An electromagnet is utilized to connect between a translation stage and the micro-resonator holder temporally for performing a portable design.
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The Mg intercombination transition is an attractive candidate for a future optical frequency standard. Results of a detailed experimental and theoretical study of Ramsey-Borde interferometry using both thermal and laser-cooled atoms will... more
The Mg intercombination transition is an attractive candidate for a future optical frequency standard. Results of a detailed experimental and theoretical study of Ramsey-Borde interferometry using both thermal and laser-cooled atoms will be presented. Presently a stability of 5.5/spl middot/10/sup -13///spl radic//spl tau/ has been achieved.
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A time domain atom interferometer is used to compare the frequency of the Mg intercombination transition at 457 nm with an optical oscillator with sub-kHz resolution. An estimated accuracy of 2/spl middot/10/sup -15/ is achieved with... more
A time domain atom interferometer is used to compare the frequency of the Mg intercombination transition at 457 nm with an optical oscillator with sub-kHz resolution. An estimated accuracy of 2/spl middot/10/sup -15/ is achieved with laser cooled and trapped atoms. The resolved line Q-factor is better than 10/sup 12/.
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We discuss further extensions of time-domain atom interferometry, like multiple-beam interferometry and measurements of the spatial and temporal coherence properties of the partial waves as well as applications for high precision... more
We discuss further extensions of time-domain atom interferometry, like multiple-beam interferometry and measurements of the spatial and temporal coherence properties of the partial waves as well as applications for high precision measurements.
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Optical comb spacing of 2.5 nm was generated from fused-quartz micro-resonator with Q ~ 107. An electromagnet is utilized to connect between a translation stage and the micro-resonator holder temporally for performing a portable design.
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We employed a gold coated glass cover plate to fabricate the dual compact free running fiber laser combs. It had been used for a difference of repetition rates tunable LIDAR (light detection and ranging) system. Our study shows that the... more
We employed a gold coated glass cover plate to fabricate the dual compact free running fiber laser combs. It had been used for a difference of repetition rates tunable LIDAR (light detection and ranging) system. Our study shows that the ranging precision is 0.4 μm and the non-ambiguity range is 2.1 m with averaging time of 0.4 s for the distance of 1.09 m. The system with 1 kHz-high update rate and the large non-ambiguity range is potentially useful for manufacturing application applied in absolute distance measurement.
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We present the first precise frequency measurement of the 21S0-3 1D2 two-photon transition in He at 1009 nm. The laser source at 1009 nm is stabilized on an optical frequency comb to perform the absolute frequency measurement. The... more
We present the first precise frequency measurement of the 21S0-3 1D2 two-photon transition in He at 1009 nm. The laser source at 1009 nm is stabilized on an optical frequency comb to perform the absolute frequency measurement. The absolute frequency of 21S0-3 1D2 transition is experimentally determined to be 594 414 291 803(13) kHz with a relative uncertainty of 1.6 × 10 which is more precise than previous determination by a factor of 25. Combined with the theoretical ionization energy of the 31D2 state, the ionization energy of the2 1S0 state is determined to be 960 332 040 866(24) kHz. In addition, the deduced 21S0 and 2 3S1 Lamb shifts are 2806.817(24) and 4058.8(24) MHz respectively which are 1.6 times better than previous determinations.
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Stabilization of the relative carrier-envelope (CE) phase for hybridly synchronized two-color fs Yb and Er fiber laser systems is demonstrated for the first time by utilizing the feedforward scheme based on an acousto-optic frequency... more
Stabilization of the relative carrier-envelope (CE) phase for hybridly synchronized two-color fs Yb and Er fiber laser systems is demonstrated for the first time by utilizing the feedforward scheme based on an acousto-optic frequency shifter.
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Metallic rod array is successfully demonstrated to be integrated a parallel plate waveguide and used as a slab-waveguide for sensing applications. Both the waveguide properties are characterized from the transmission spectra using... more
Metallic rod array is successfully demonstrated to be integrated a parallel plate waveguide and used as a slab-waveguide for sensing applications. Both the waveguide properties are characterized from the transmission spectra using different polarization conditions of terahertz electromagnetic fields, which are parallel and perpendicular to the rod axis. When THz field polarization is parallel to the rod axis, there is high-pass filtering feature with structure-period-dependent threshold frequency, corresponding to the plasma frequency of the rod-array composite. For the polarization perpendicular to the rod axis, there is Bragg diffraction frequency as forbidden band with considerably low transmission power. The metal-rod-array integrated parallel-plate waveguide is connected with a microfluidic channel to sense liquids, and the minimum detectable quantity is about 13μmol/mm3. The metal-rod-array slab waveguide is able to sense thinfilm with nanometer level, and the detectable optical path difference is down to λ/2380. The sensor properties of multiple functions for sensing various analyte conformations, microfluidic integration and high sensitivity would be applied in biomedicine and biochemical applications.
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Research Interests: Materials Science, Optics, Medicine, Optical Waveguides, Optoelectronics, and 15 moreDIELECTRIC, Laser Linewidth, Photonic Crystal, Terahertz, Optical Waveguide, Optical physics, Optical fiber, Spectral Properties, Photonic crystal fiber, Planar Waveguide, Bragg Grating, Optical Filters, Insertion Loss, Notch Filters, and Electrical And Electronic Engineering
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We report a precision frequency measurement of the (4)He 2(1)S(0)→2(1)P(1) transition at 2058 nm. The saturated absorption spectroscopy is performed in a rf discharge sealed-off cell with a volume Bragg grating-based Tm:Ho:YLF laser. The... more
We report a precision frequency measurement of the (4)He 2(1)S(0)→2(1)P(1) transition at 2058 nm. The saturated absorption spectroscopy is performed in a rf discharge sealed-off cell with a volume Bragg grating-based Tm:Ho:YLF laser. The absolute transition frequency measured using a fiber optical frequency comb is 145 622 892 822 (183) kHz with a relative uncertainty of 1.3×10(-9). Our result is ten times more precise than current best theoretical calculations and is in reasonable agreement with the calculated values. However, the ionization energy of the 2(1)P(1) state, derived from our result and other precisely measured transitions, shows a discrepancy of approximately 3.5σ with the most precise atomic theory. We have also determined the isotope shift between (3)He and (4)He to be 4248.7 (5.3) MHz, which is more precise than the previous measurement by one order of magnitude.
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The mode number of the comb line involved in the optical frequency measurement was determined using two mode-locked, erbium-doped fiber laser combs operated at different repetition rates independently of the frequency fluctuation of the... more
The mode number of the comb line involved in the optical frequency measurement was determined using two mode-locked, erbium-doped fiber laser combs operated at different repetition rates independently of the frequency fluctuation of the laser under measurement (LUM). A simple measurement process is presented to determine the difference in mode number between the two laser combs and the comb mode number, yielding the absolute frequency of the LUM.
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Research Interests: Algorithms, Materials Science, Optics, Medicine, Terahertz spectroscopy, and 15 moreAnisotropy, Interferometry, DIELECTRIC, Terahertz, Refractive Index, Optical physics, Optics and Photonics, Reproducibility of Results, Acrylic Resins, Optical Fibers, Fiber Optic Technology, Polypropylenes, Electrical And Electronic Engineering, Biosensing Techniques, and Terahertz radiation
This work demonstrates the feasibility of a terahertz time-domain spectrometer based on a subwavelength-diameter plastic wire (SPW) for sensing applications. The dispersion property of the SPW is experimentally and theoretically studied.... more
This work demonstrates the feasibility of a terahertz time-domain spectrometer based on a subwavelength-diameter plastic wire (SPW) for sensing applications. The dispersion property of the SPW is experimentally and theoretically studied. The SPW exhibits a low and controllable waveguide dispersion, which can be engineered by changing the core diameter, the core index, and the cladding index of the wire. Two white powders, tryptophan and polyethylene, deposited on the bottom of the wire can be successfully distinguished based on the waveguide dispersion of SPW. The SPW would be a promising candidate for combination with biochips for sensing minute molecules.
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Research Interests: Materials Science, Optics, Spectroscopy, Medicine, Optical Waveguides, and 15 moreNanowires, Sensors, Computer Simulation, Plastics, Refractive Index, Absorption, EVANESCENT WAVE, Optical physics, Optics and Photonics, Powders, High Sensitivity, Fiber Optic Technology, Equipment Design, Electrical And Electronic Engineering, and Alcohols
Lasers from four national metrological institutes (NMIs) were compared as part of the CCL-K11 ongoing key comparison, initiated by the 13th meeting of the Comit Consultative des Longueurs (CCL) in 2007. The absolute frequency of the f... more
Lasers from four national metrological institutes (NMIs) were compared as part of the CCL-K11 ongoing key comparison, initiated by the 13th meeting of the Comit Consultative des Longueurs (CCL) in 2007. The absolute frequency of the f component of the R(127) 11-5 transition of molecular iodine was measured for these lasers following the technical protocol for CCL-K11. The results of
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Author Institution: Institute of Photonics Technologies, National Tsing Hua University, Hsinchu 30013, Taiwan; Center for Measurement Standards, Industrial Technology Research Institute, Hsinchu 30011, Taiwan; Department of Chemistry and... more
Author Institution: Institute of Photonics Technologies, National Tsing Hua University, Hsinchu 30013, Taiwan; Center for Measurement Standards, Industrial Technology Research Institute, Hsinchu 30011, Taiwan; Department of Chemistry and Department of Physics and Astronomy; University of Waterloo, Waterloo, ON N2L 3G1, Canada; Institute of Photonics Technologies, National Tsing Hua University and Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
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Author Institution: Institute of Photonics Technologies, National Tsing Hua University, Hsinchu, Taiwan, R.O.C.; Center of Measurement Standards, Industrial Technology Research Institute, Hsinchu, Taiwan, R.O.C.; Department of Chemistry... more
Author Institution: Institute of Photonics Technologies, National Tsing Hua University, Hsinchu, Taiwan, R.O.C.; Center of Measurement Standards, Industrial Technology Research Institute, Hsinchu, Taiwan, R.O.C.; Department of Chemistry and Department of Physics and Astronomy, University of Waterloo, Canada; Department of Physics and Institute of Photonics Technologies, National Tsing Hua University, Hsinchu, Taiwan, R.O.C.
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In our previous work on the Lamb-dips of the ν2 fundamental band transitions of H3+, the saturated absorption spectrum was obtained by third-derivative spectroscopy using frequency modulation with an optical parametric oscillator (OPO).... more
In our previous work on the Lamb-dips of the ν2 fundamental band transitions of H3+, the saturated absorption spectrum was obtained by third-derivative spectroscopy using frequency modulation with an optical parametric oscillator (OPO). However, frequency modulation also caused errors in the absolute frequency determination. To solve this problem, we built a tunable offset locking system to lock the pump frequency of the OPO to an iodine-stabilized Nd:YAG laser. With this improvement, we were able to scan the OPO idler frequency precisely and obtain the saturated absorption profile using intensity modulation. Furthermore, ion concentration modulation was employed to subtract the background noise and increase the signal-to-noise ratio. To determine the absolute frequency of the idler wave, the OPO signal frequency was locked to an optical frequency comb. The absolute frequency accuracy of our spectrometer was better than 7 kHz, demonstrated by measuring the wavelength standard transition of methane at 3.39 μm. Finally, we measured 16 transitions of H3+ and our results agree very well with other precision measurements. This work successfully resolved the discrepancies between our previous measurements and other precision measurements.
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Abstract. We propose and demonstrate a compact and portable-size 84-GHz passive mode-locked fiber laser, in which a dual-fiber coupled fused-quartz microresonator is employed as the intracavity optical comb filter as well as the optical... more
Abstract. We propose and demonstrate a compact and portable-size 84-GHz passive mode-locked fiber laser, in which a dual-fiber coupled fused-quartz microresonator is employed as the intracavity optical comb filter as well as the optical nonlinear material for optical frequency comb generation. About eight coherent optical tones can be generated in the proposed fiber laser. The 20-dB bandwidth is larger than 588 GHz. The full-width half-maximum pulse-width of the proposed laser is 2.5 ps. We also demonstrate the feasibility of using the proposed passive mode-locked fiber laser to carry a 5-Gbit/s on-off-keying signal and transmit over 20-km standard single mode fiber. A 7% forward error correction requirement can be achieved, showing the proposed fiber laser can be a potential candidate for fiber-wireless applications.
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A compact and portable microresonator-based optical frequency comb generation system was developed to provide an array of multiwavelength laser sources for dense wavelength division multiplexing (DWDM) fiber optic communication. The... more
A compact and portable microresonator-based optical frequency comb generation system was developed to provide an array of multiwavelength laser sources for dense wavelength division multiplexing (DWDM) fiber optic communication. The reported comb generation system was capable of producing comb lines after 7 km of travel without environmental control, indicating the effectiveness of the packaging. The comb spacing is about 98.3 GHz (i.e., ∼0.79 nm around 1553 nm), thus the comb line frequencies coincide nicely with 100-GHz DWDM channel frequencies, assuming the suggested channel bandwidth is 0.3 nm. The quality of selected comb lines was evaluated individually based on error vector magnitude (EVM) measurements along with RF spectrum measurements. An average EVM value observed is as low as 3.8%, close to typical EVM values of less than 3% used for fiber optic communication.
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Hannover, University, Diss., 1998 (Nicht für den Austausch).
In this work, we demonstrated the depressed beat signal linewidth of 100 kHz, and generated frequency-tunable terahertz radiation with tuning ranges from 0.2 THz to 1.24 THz from two external-cavity diode lasers.
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The HeH+ ion, one of the simplest diatomic molecular ions, plays an important role not only in the quantum mechanical calculations but also, potentially, in the astrophysics. In this report, we demonstrated the first observation of the... more
The HeH+ ion, one of the simplest diatomic molecular ions, plays an important role not only in the quantum mechanical calculations but also, potentially, in the astrophysics. In this report, we demonstrated the first observation of the saturation absorption spectrum of the HeH+ using a continuous-wave, singly resonant, single frequency and widely tunable optical parametric oscillator in the mid-infrared region. The HeH+ ions were produced in an ethanol cooled extended negative glow discharge tube at -70 degrees centigrade with flowing mixtures of helium and hydrogen. The negative glow region of discharge was extended by applying an axial magnetic field of 300 gauss. The saturation spectrum of HeH+ (R(1) transition of {nu}=1-0 band at 90,788 GHz) was observed by scanning the frequency of the pump laser and demodulated at third harmonics by a lock-in amplifier. The investigations of the linewidth and the frequency measurement will be also presented.
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We employed a gold coated glass cover plate to fabricate dual compact free running fiber laser combs based LIDAR (light detection and ranging) system with tunable difference of repetition rates. Our study shows that the ranging precision... more
We employed a gold coated glass cover plate to fabricate dual compact free running fiber laser combs based LIDAR (light detection and ranging) system with tunable difference of repetition rates. Our study shows that the ranging precision is 0.4 μm and the non-ambiguity range is 2.1 m with averaging time of 0.4 s for the distance of 1.09 m by the time-of-flight method. The system with 1 kHz-high update rate and the large non-ambiguity range is potentially useful for manufacturing or machining application applied in absolute distance measurement.
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A passively mode-locked Er:fiber laser is frequency-stabilized to a stability of 3×10-13 at 1 s. Application to the frequency measurement of an I2-stabilized Nd:YAG laser is described.
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ABSTRACT The frequency of a passively mode-locked Er:fiber laser is stabilized to a microwave frequency standard. The residual frequency fluctuations are 0.3 and 1.8 mHz for the 10thharmonic of the repetition frequency and offset... more
ABSTRACT The frequency of a passively mode-locked Er:fiber laser is stabilized to a microwave frequency standard. The residual frequency fluctuations are 0.3 and 1.8 mHz for the 10thharmonic of the repetition frequency and offset frequency, respectively.