Browsing by Author "Hsieh, CF"

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A liquid crystal phase shifter with a tuning range of over 360 degrees around 1 THz
(2005)
Chen, CY
;
Hsieh, CF
;
Pan, RP
;
Pan, CL
;
光電工程學系
Tunable phase shift over 271 radians (360 degrees) at THz frequencies is achieved with a sandwiched liquid crystal (LC) cell operated over a broad range using magnetically controlled birefriengence.
A liquid-crystal-based terahertz tunable Lyot filter
(2005)
Pan, RP
;
Chen, CY
;
Hsieh, CF
;
Pan, CL
;
電子物理學系
A tunable Lyot filter operating in the terahertz frequency range is demonstrated by using fixed and variable nematic liquid crystals.
Control of enhanced THz transmission through metallic hole arrays using nematic liquid crystal
(2005-05-30)
Pan, CL
;
Hsieh, CF
;
Pan, RP
;
Tanaka, M
;
Miyamaru, F
We demonstrate frequency tuning of enhanced THz radiation transmitted through a two- dimensional metallic hole array ( 2D- MHA) by controlling the index of refraction of the medium filling the holes and adjacent to the 2D- MHA on one side. The medium is a nematic liquid crystal ( NLC) and its index of refraction is varied using magnetically controlled birefringence of the NLC. With the NLC, the peak transmission frequency of the 2D- MHA shift to the red by 0.112 THz and can be tuned from 0.193 to 0.188 THz. The peak transmittance is as high as 70% or an enhancement of 2.42 times, considering the porosity of the 2D- MHA. As a tunable THz filter, this device exhibits a continuous tuning range of 4.7 GHz, a low insertion loss of 2.35 to 1.55 dB and a quality factor of similar to 4- 5. (C) 2005 Optical Society of America.
Control of THz transmission through two-dimensional metallic photonic crystals
(2005)
Pan, CL
;
Hsieh, CF
;
Pan, RP
;
Tanaka, M
;
Miyamaru, F
We demonstrate frequency tuning of resonantly enhanced THz radiation transmitted through a two-dimensional metallic photonic crystal on a liquid crystalline "substrate".
Effects of hole material on enhanced terahertz transmission through metallic hole arrays
(2005)
Lo, C
;
Hsieh, CF
;
Pan, RP
;
Pan, CL
;
光電工程學系
Enhanced, multi-peak THz transmission peaks from metallic hole arrays filled with UV-gel are studied. Different SPP-like surface wave modes are identified.
Liquid-crystal-based terahertz tunable Lyot filter
(2006-03-06)
Chen, CY
;
Pan, CL
;
Hsieh, CF
;
Lin, YF
;
Pan, RP
A two-element tunable Lyot filter operating in the terahertz (THz) frequency range is demonstrated. The central bandpass frequency of the filter can be continuously tuned from 0.388 to 0.564 THz (a fractional tuning range of 40%) using magnetically controlled birefringence in nematic liquid crystals. The transmission bandwidth is 0.1 THz and the insertion loss of the present device is 8 dB due to the scattering of LC molecules in the thick LC cells. This filter can be operated at room temperature. (c) 2006 American Institute of Physics.
Magnetically tunable room-temperature 2 pi liquid crystal terahertz phase shifter
(2004-06-14)
Chen, CY
;
Hsieh, CF
;
Lin, YF
;
Pan, RP
;
Pan, CL
Tunable phase shift up to 360degrees at 1 THz is achieved with a liquid crystal (LC) device. The key to this design is (1) the use of a nematic LC, E7, which exhibits a birefringence of similar to0.17 (0.2-1.2 THz); (2) a LC cell (3-mm in thickness) with sandwiched structure to increase the interaction length while minimizing interface Fresnel losses; and (3) the use of magnetic field to align the thick LC cell and achieve continuous tuning of phase from 0 to 360degrees. This device can be operated over a broad range near room temperature. (C) 2004 Optical Society of America.
Observing the dynamic variation of the binding force between rhodostomin ligand and integrin alpha(IIb)beta(3) receptor using a photonic force microscope
(2004)
Chang, BJ
;
Hsieh, CF
;
Lin, CH
;
Chi, S
;
Hsu, L
The conformational change of integrin alpha(IIb)beta(3) plays an important role in clot formation. However, the correlation between the structure and the function of integrin beta(IIb)beta(3) in interacting with its ligand is still not clear. In this report, we focus on the dynamic variation of the binding between integrin alpha(IIb)beta(3) and its ligand, rhodostomin by using a photonic force microscopy (PFM). The PFM is used to trap a rhodostomin-coated bead and, then, shift it to bind a surrounding CHO alpha(IIb)beta(3) cell. Meanwhile, it tracks, with a resolution of 1MHz, the Brownian fluctuations of the trapped bead. Theoretically, the smaller the amplitude of the Brownian fluctuations, the stronger the stiffness of the binding force between the rhodostomin and the CHO alpha(IIb)beta(3) cell. Experimentally, a significant decrease of the Brownian fluctuations was observed during the interval between the 360(th) seconds and the 400(th) seconds after the trapped rhodostomin-coated bead contacted an integrin-expressed CHO alpha(IIb)beta(3) cell. This observation reveals that it takes the rhodostomin 360 seconds to seek the correct position to bind to the integrin alpha(IIb)beta(3). After 400 seconds, the rhodostomin has bound rigidly with the integrin alpha(IIb)beta(3) We presume that the integrin alpha(IIb)beta(3) has reached its final stage of conformational change.
Voltage controlled liquid crystal terahertz quarter wave plate
(2005)
Hsieh, CF
;
Chen, HL
;
Chen, CY
;
Pan, RP
;
Pan, CL
We demonstrate an electrically switchable THz quarter wave plate using nematic liquid crystals.
Voltage-controlled liquid-crystal terahertz phase shifter and quarter-wave plate
(2006-04-15)
Hsieh, CF
;
Pan, RP
;
Tang, TT
;
Chen, HL
;
Pan, CL
Phase shift exceeding pi/2 at 1 THz is demonstrated by using electrically controlled birefringence in a homeotropically aligned nematic liquid crystal (E7) cell, 570 mu m in thickness. The driving voltage required for a phase shift of 90 degrees is 125 V (rms). We demonstrate that the phase shifter works as an electrically switchable quarter-wave plate at I THz. The device can also be used as an electrically tuned phase compensator around the quarter-wave point near 1 THz. (c) 2006 Optical Society of America.