Browsing by Author "Shy, Jow-Tsong"

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Absolute frequency measurements of the molecular iodine hyperfine transitions at 535 nm
(2013-07-01)
Shie, Nang-Chian
;
Chen, Shih-En
;
Chang, Chun-Yu
;
Hsieh, Wen-Feng
;
Shy, Jow-Tsong
We report absolute frequency measurements of the alpha(1), alpha(10), and alpha(15) hyperfine components of molecular iodine P(28) 30-0 line at 535 nm. A frequency-doubled 1070 nm Nd:GdVO4 laser is frequency stabilized to a hyperfine component of I-2 using the third-harmonic demodulation technique. The frequency stability of 3 x 10(-12) is achieved at 10 s averaging time when its frequency is stabilized to the alpha(1) component. An optical frequency comb is used to measure its absolute frequency. The pressure shift is investigated to obtain the absolute frequency at zero pressure. The effect of pressure and power broadening of the a10 component are also investigated. This light source can be used for investigating parity nonconservation effect in atomic thallium. (C) 2013 Optical Society of America
CW-pumped evanescent amplification based on side-polished fiber with heavily Er3+-doped glass overlay
(2006-08-01)
Chen, Nan-Kuang
;
Zhang, Liyan
;
Hsu, Kuei-Chu
;
Hu, Lili
;
Chi, Sien
A novel diffractive-pumping scheme is proposed to improve the evanescent amplification using blazed fiber grating for the first time. We also investigate the cw-pumped-evanescent amplification at 1.55 mu m wavelength with the relative optical gain pumped at 1480 nm of around 2 dB based on side-polished fiber with the effective interaction length as long as 16 mm and with a heavily Er3+-doped (N-Er(3+) > 1.19 x 10(21) ions/cm(3)), low refractive index (n(1550) < 1.47) glass overlay, which has no concentration quenching (tau(f) = 9.0 ms).
Dynamics and reversibility of oxygen doping and de-doping for conjugated polymer
(2008-05-15)
Liao, Hua-Hsien
;
Yang, Chia-Ming
;
Liu, Chien-Cheng
;
Horng, Sheng-Fu
;
Meng, Hsin-Fei
We perform comprehensive long-time monitoring of the p-doping and de-doping of poly(3-hexyl thiophene) under changing external conditions of oxygen, light, and temperature. They are shown to be controlled by the complex adsorption and desorption process with time scales ranging from seconds to weeks. The oxygen doping at atmospheric pressure takes several hours in the dark. The doping is dramatically accelerated to be within seconds with light of wavelength of 500-700 nm. Even at low oxygen pressure of 10(-4) torr doping occurs within minutes with light. The de-doping by oxygen desorption takes as long as weeks at room temperature and vacuum of 10(-4) torr, but when the temperature is raised to near the polymer glass temperature of 370 K, the de-doping is accelerated to minutes as the enhanced chain motion releases the trapped oxygen. Even though visible and near infrared light causes very efficient doping within seconds or minutes depending on vacuum level, such light-induced doping is not a chemical reaction and is fully reversible by thermal annealing at the end without sacrificing the mobility. For the polymer field-effect transistors, only the carrier density is changed while the mobility remains roughly a constant for all the conditions. (c) 2008 American Institute of Physics.
Enhanced photovoltaic response of organic solar cell by singlet-to-triplet exciton conversion
(2007-03-26)
Yang, Chia-Ming
;
Wu, Chi-Hui
;
Liao, Hua-Hsin
;
Lai, Kuei-Yuan
;
Cheng, Hong-Ping
Ir complex was doped to conjugated polymers, and the photoinduced absorption of triplet excitons in host materials was examined. A greatly enhanced intersystem crossing rate was observed, despite the decrease in triplet exciton lifetime. The authors find that the steady-state triplet exciton population in host polymer would increase by an order of magnitude. Conjugated polymer/colloidal CdSe nanocrystal hybrid solar cells were fabricated and the effect of Ir-complex doping on photovoltaic response was studied. It was found that due to the enhanced singlet-to-triplet conversion, greatly enhanced photovoltaic response of these hybrid organic solar cells was observed. The results suggest that triplet solar cells may be achieved by doping conventional photovoltaic materials with transition-metal complexes. (c) 2007 American Institute of Physics.
Frequency measurement of the 6P(3/2) -> 7S(1/2) transition of thallium
(2013-12-30)
Shie, Nang-Chian
;
Chang, Chun-Yu
;
Hsieh, Wen-Feng
;
Liu, Yi-Wei
;
Shy, Jow-Tsong
The saturated absorption spectrum of the 6P(3/2) -> 7S(1/2) transition of Tl-203 and Tl-205 in a hollow cathode lamp has been observed with a frequency-doubled 1070 nm Nd : GdVO4 laser. The third-derivative spectrum of the hyperfine components are obtained using the wavelength modulation spectroscopy and used to stabilize the laser frequency. The analysis of the error signal shows that the frequency stability reaches 30 kHz at 1 s averaging time. Such a frequency-stabilized light source at 535 nm can be used for laser cooling of thallium and for investigating the parity non-conservation effect in thallium. The absolute frequencies of hyperfine components are measured with an accuracy of 30 MHz using a precision wavelengthmeter. Including the pressure shift correction, the center of gravity of the transition frequency is determined to an accuracy of 22 MHz for both isotopes. Meanwhile, the isotope shift derived is in good agreement with earlier measurement.
Large enhancement of intersystem crossing in polyfluorenes by iridium-complex doping
(2007-01-01)
Liao, Hua-Hsien
;
Yang, Chia-Ming
;
Wu, Chi-Hui
;
Horng, Sheng-Fu
;
Lee, Wei-Shan
Photoinduced absorption is used to study the intersystem crossing (ISC) rate of two polyfluorenes doped with iridium (III) tris[2-(4-totyl)pyridinato-N,C2]. It is found that the triplet exciton lifetime of polyfluorene is reduced by the dopants. But instead of decreasing, the population density of polyfluorene triplet exciton increases by almost one order of magnitude. The finding shows that the ISC rate can increase over 100 times due to the spin-orbital interaction with the Ir ion even though it is covered by the ligands. Specifically, the ISC lifetime changes from the intrinsic value of 62 ns to as short as 0.28 ns upon 10% doping.
Lnfrared photocurrent response of charge-transfer exciton in polymer bulk heterojunction
(2008-02-25)
Yang, Chia-Ming
;
Tsai, Pei-Yu
;
Horng, Sheng-Fu
;
Lee, Kuan-Chen
;
Tzeng, Shin-Rong
We study the charge-transfer exciton absorption and photocurrent response in solution-processed bulk heterojunction based on poly(3-hexylthiophene) donor and (6,6)-phenyl-C(61)-butyric acid methyl ester acceptor in the near-infrared wavelength region. While the exciton absorption exists only for wavelength below 650 nm, direct generation of charge-transfer exciton formed between the donor and acceptor extends the absorption wavelength to 950 nm. For films with micrometer thickness, the photon-to-electron conversion efficiency is about 60% at 750 nm wavelength under reverse voltage bias and the photocurrent to dark current ratio is about 8.6 at 900 nm and remains 3.6 even at 1000 nm. Photodetector with high sensitivity covering exclusively the 650-1000 nm near infrared region can therefore be made without a low bandgap material. The charge-transfer exciton absorption coefficient and photocurrent sensitivity depend on the annealing condition which controls the donor-acceptor morphology. (c) 2008 American Institute of Physics.
Single frequency 1070 nm Nd:GdVO(4) laser using a volume Bragg grating
(2011-10-24)
Shie, Nang-Chian
;
Hsieh, Wen-Feng
;
Shy, Jow-Tsong
;
光電工程學系
;
Department of Photonics
We demonstrate a single frequency diode-pumped Nd:GdVO(4) laser at 1070 nm using a volume Bragg grating as the output coupler of a short plano-concave cavity. The TEM(00) output had a maximum power of 300 mW and a linewidth less than 23 MHz. The beam propagation parameter M(2) and the divergence angle at 200 mW were 1.2 and 0.37 degrees, respectively. The single frequency tuning range was 5.1 GHz at 100 mW. Upon locking the laser frequency to a confocal reference cavity, a relative stability of 7.58 kHz was achieved. If frequency doubled, such as using a periodically-poled lithium niobate (PPLN) crystal, this laser offers an excellent light source for parity non-conservation experiments of atomic thallium.
Single frequency 1070 nm Nd:GdVO4 laser using a volume Bragg grating
(2011-10-24)
Shie, Nang-Chian
;
Hsieh, Wen-Feng
;
Shy, Jow-Tsong
;
光電工程學系
;
光電工程研究所
We demonstrate a single frequency diode-pumped Nd:GdVO4 laser at 1070 nm using a volume Bragg grating as the output coupler of a short plano-concave cavity. The TEM00 output had a maximum power of 300 mW and a linewidth less than 23 MHz. The beam propagation parameter M-2 and the divergence angle at 200 mW were 1.2 and 0.37 degrees, respectively. The single frequency tuning range was 5.1 GHz at 100 mW. Upon locking the laser frequency to a confocal reference cavity, a relative stability of 7.58 kHz was achieved. If frequency doubled, such as using a periodically-poled lithium niobate (PPLN) crystal, this laser offers an excellent light source for parity non-conservation experiments of atomic thallium.
Solar-pumped active device
(2006-02-23)
Chi, Sien
;
Chen, Nan-Kuang
;
Shy, Jow-Tsong
The present invention provides a solar-pumped active device which utilizes a holographic antenna grating on a solar energy silicon substrate to select specific diffracted wavelength and couple pump wavelength in an approximately vertical way and converge the pump wavelength to excite an optical gain medium so that an optical amplifier or a laser can be obtained. The present invention requires no big size and is flexible over the surface shape and is suitable for free space optical communications on the ground and satellite optical communications. It means that the holographic antenna grating can be applied on the top floor of a building or on the glass surface of an outer wall. If it is applied to a satellite, the present invention can be deposited on a solar energy cell substrate to form a high optical amplification so that not only the electricity required in satellite optical communications can be reduced, but also a high-speed and large capacity of data can be transferred between satellites.
Solar-pumped active device
(2007-08-16)
Chi, Sien
;
Chen, Nan-Kuang
;
Shy, Jow-Tsong
The present invention provides a solar-pumped active device which utilizes a holographic antenna grating on a solar energy silicon substrate to select specific diffracted wavelength and couple pump wavelength in an approximately vertical way and converge the pump wavelength to excite an optical gain medium so that an optical amplifier or a laser can be obtained. The present invention requires no big size and is flexible over the surface shape and is suitable for free space optical communications on the ground and satellite optical communications. It means that the holographic antenna grating can be applied on the top floor of a building or on the glass surface of an outer wall. If it is applied to a satellite, the present invention can be deposited on a solar energy cell substrate to form a high optical amplification so that not only the electricity required in satellite optical communications can be reduced, but also a high-speed and large capacity of data can be transferred between satellites.