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ABSTRACT: A new scheme is proposed to measure the electro-optical (EO) and converse-piezoelectric (CPE) coefficients of the PMN-PT ceramics simultaneously, in which the PMN-PT ceramics acts as the guiding layer of a symmetrical metal-cladding waveguide. As the applied electric field exerts on the waveguide, the effective refractive index (RI) (or synchronous angle) can be effectively tuned from a selected mode to another adjacent mode owing to the high sensitivity and the small spacing of the ultra-high order modes. Subsequently, a correlation between EO and CPE coefficients is established. With this correlation and the measurement of the effective RI change to the applied voltage, the quadratic EO and CPE coefficients of PMN-PT ceramics are obtained simultaneously. The obtained results are further checked by fitting the variations of effective RI to a quadratic function. Our measurement method can be extended to a wide range of other materials.
Optics Express 06/2012; 20(13):13833-40. · 3.59 Impact Factor
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ABSTRACT: Since novel optoelectronic devices based on the peculiar behaviors of the tunneling probability, e.g., resonant tunneling
devices (RTD) and band-pass filter, are steadily proposed, the analytic transfer matrix (ATM) method is extended to study
these devices. For several examples, we explore the effect of the scattered subwaves on tunneling; it is shown that the resonant
or band-pass structures in tunneling probability are determined by the phase shift results from the scattered subwaves.
Keywordsquantum tunneling–WKB approximation–the ATM method, subwaves
Science China: Physics, Mechanics and Astronomy 04/2012; 54(3):388-392. · 0.78 Impact Factor
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ABSTRACT: A widebandwidth optical delay line is a useful device for various fascinating applications, such as optical buffering and processing of ultrafast signal. Here, we experimentally demonstrated effective slow light of sub-picosecond signal over 10 THz frequency range by employing the wide slow light modes in thick symmetrical metal-cladding optical waveguide (SMCOW). Ultrahigh-order guided modes travelling as slow light in waveguide together with strong confinement provided by metal-cladding makes this scheme nearly material dispersion independent and compatible with wide bandwidth operation.
Optics Express 04/2012; 20(9):9409-14. · 3.59 Impact Factor
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ABSTRACT: The giant Goos–Hänchen shift on a long-range surface plasmon (LRSP) configuration is examined theoretically. This lateral shift at the resonance of the LRSP can be two orders of magnitude greater than a wavelength. The analytical formulas of the radiative damping and the intrinsic damping of the LRSP are derived. It is found that the thicknesses of the second medium and the metal film determine the radiative damping and the intrinsic damping is illuminated by the imaginary part of the dielectric constant of the metal. Negative lateral beam shift occurs when the intrinsic damping is larger than the radiative damping. The theoretical results show good agreement with the predictions of the formulas.
Journal of optics 01/2011; 13(3):035002. · 1.57 Impact Factor
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ABSTRACT: A generalized reflection time which follows directly from the Schrödinger equation without approximation is obtained. By the Winger-Eisenbud approach, this reflection time is conceptually well defined and can be applied to arbitrary continuous potentials including both quantum tunneling and quantum reflection issue. A simple explanation for the quantum reflection phenomenon is proposed and the explicit expression of the difference between the quantum reflection time and the classical reflection time is also derived.
Phys. Rev. A. 12/2009; 80(6).
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ABSTRACT: Electrical tuning of polarization beam splitting is demonstrated in the structure of symmetrical metal-cladding waveguide by introducing optically nonlinear material into both the coupling prism and the guiding layer. Due to the anisotropy of the coupling material, different excitation conditions for TE and TM modes are obtained, which results in polarization-dependent reflections and transmissions. And the splitting effect of the two orthogonally polarized beams can be manipulated through an electrical modulation of the guiding layer properties.
Optics Express 09/2009; 17(16):13309-14. · 3.59 Impact Factor
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ABSTRACT: By using the technique of the attenuated total reflection, the complex second hyperpolarizability for the quadratic electro-optic effect of a linear conjugated polymer is determined at the wavelength of the absorption edge by employing the data measured from different guided wave resonance dips. The values and the signs of the real and imaginary parts of the second hyperpolarizability are simultaneously obtained without employing the Kramers-Kronig transformation.
EPL (Europhysics Letters) 08/2009; 87(2):24003. · 2.17 Impact Factor
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ABSTRACT: An experimental method based on the attenuated-total-reflection technique is reported to determine the dispersions of all quadratic electrooptic tensor elements and dc-Kerr coefficient of a linear conjugated polymer in the off-resonant region.
IEEE Journal of Quantum Electronics 06/2009; · 1.88 Impact Factor
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ABSTRACT: Without solving the Schrödinger equation, exact and general expressions of the reflection and transmission probabilities for a quantum particle through an arbitrary potential barrier are presented by using the analytical transfer matrix method. It is seen that in addition to the parameters of the ambience and both the start and the final point of the barrier, the unique dependence on the formulae is the total phase shift accumulated by the mainwaves and the subwaves.
Journal of Physics A Mathematical and Theoretical 10/2008; 41(46):465301. · 1.56 Impact Factor
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ABSTRACT: A structure of symmetrical metal-cladding waveguide, which contains optically nonlinear material in the guiding layer, is proposed to control the lateral shift of the reflected beam via an external electric field. Owing to the high sensitivity of ultrahigh-order modes, any minute index change of the waveguide will lead to a dramatic variation of the resonance condition, which gives rise to a change of the lateral beam displacement. Experimental result shows that the electric control of the lateral beam shift is realized in a range of 720 μm.
Applied Physics Letters 09/2008; 93(9):091103-091103-3. · 3.84 Impact Factor
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ABSTRACT: It is demonstrated that the superprism effect is greatly enhanced in the configuration of a symmetrical metal-cladding waveguide owing to the strong dispersion effect of ultrahigh-order modes. The experimental result shows that a notable spatial displacement of the reflected beam as large as 0.9 mm is achieved within a variation of 0.15 nm in wavelength.
Optics Letters 07/2008; 33(11):1276-8. · 3.40 Impact Factor
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ABSTRACT: BACKGROUND: The ‘A2 + B3’ type of polymerization has been demonstrated to be an alternative route towards hyperbranched polymers. Some highly crosslinked hyperbranched polymers have been prepared via copper(I)-catalyzed click reactions of multivalent azides and alkynes. To obtain hyperbranched polymers without gelation and develop the A2 + B3 type of polymerization based on click reactions, the specific reaction conditions need to be investigated.RESULTS: In this work, a hyperbranched polytriazole (hb-PTA) was synthesized through the A2 + B3 approach using a click reaction. 4-N,N′-bis(2-azidoethyl)amino-4′-nitroazobenzene and 1,3,5-tris(alynyloxy)benzene were synthesized for use as the A2 and B3 monomers, respectively. This was a ‘one-pot’ polymerization carried out using a slow-addition method. The obtained hb-PTA was soluble in common organic solvents. The molecular structure was characterized using 1H NMR, Fourier transform infrared and gel permeation chromatography analyses. The degree of branching of hb-PTA was determined to be around 0.50.CONCLUSION: The hb-PTA was successfully synthesized via the A2 + B3 approach based on a click reaction. The polymerization conducted in dilute solution adopting slow addition of A2 to B3 resulted in hb-PTA in the absence of gelation. The obtained hb-PTA exhibited high thermal stability. Copyright © 2008 Society of Chemical Industry
Polymer International 06/2008; 57(8):965 - 974. · 1.90 Impact Factor
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ABSTRACT: An oscillating wave displacement sensor based on the enhanced Goos-Hänchen (G-H) effect in a symmetrical metal-cladding optical waveguide is proposed. Since the detected signal is irrelevant to the power fluctuation of the incident light and the magnitude of the G-H shift is enhanced to hundreds of micrometers, a 40 pm resolution is demonstrated in our experiment without employing any complicated optical equipment and servo techniques.
Optics Letters 06/2008; 33(9):1001-3. · 3.40 Impact Factor
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ABSTRACT: The hyperbranched polytriazole (hb-PTA) containing second-order nonlinear optical chromophore was synthesized through “A2 + B3” approach based on “click reaction.” Its corresponding linear analogue (l-PTA) was prepared for comparison. The hb-PTA has better solubility in common organic solvents than the l-PTA. Both the polymers exhibit good thermal stability with 5% weight loss temperatures over 260 °C. The poled film of hb-PTA exhibits much higher second-harmonic coefficient (96.8 pm/V) than that of l-PTA (23.5 pm/V). The three-dimensional spatial isolation effect resulting from the highly branched structure and the crosslinking of the terminal acetylene groups at moderate temperature play important roles in the enhancement of optical nonlinearity. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1140–1148, 2008
Journal of Polymer Science Part B Polymer Physics 05/2008; 46(12):1140 - 1148. · 1.53 Impact Factor
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ABSTRACT: Based on the attenuated-total-reflection technique, a new method has been proposed to determine the second hyperpolarizability gamma(-omega(4);omega(3),omega(2),omega(1)) of the linear conjugated polymer in the off-resonant region by means of quadratic electro-optic effect. An important feature of this method is the absence of a high-power pulse laser, resulting in more convenience and cost effectivity than other techniques.
Optics Letters 05/2008; 33(8):887-9. · 3.40 Impact Factor
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ABSTRACT: Instead of the evanescent field sensors, an oscillating wave sensor based on the Goos–Hänchen effect is proposed in this letter. It is demonstrated that as the intrinsic damping is well-matched with the radiative damping of the ultrahigh-order modes in a symmetrical metal-cladding waveguide with submillimeter scale, the enormously enhanced lateral beam shift results in a very high sensitivity of the sensor.
Applied Physics Letters 02/2008; 92(6):061117-061117-3. · 3.84 Impact Factor
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ABSTRACT: An electro-optic (EO) polymer modulator employing a symmetrical metal-cladding waveguide structure is presented. Based on the free-space coupling technique, the energy of incident light on the metal-cladding is coupled directly from free space into the waveguide without using a prism, grating and other coupling components. An externally applied voltage modulates the reflected light intensity by changing the energy coupling efficiency of the incident light into the waveguide through the refractive index of the EO polymer. The fabricated modulator achieves an 8.2% modulation depth with 10 Vp−p driving voltage at 1 MHz. The device also provides the benefits of simple fabrication and compact size owing to the use of the free-space coupling technique.
Journal of Optics A Pure and Applied Optics 12/2007; 10(1):015305. · 1.92 Impact Factor
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ABSTRACT: Both large positive and negative lateral shifts were observed for the reflected light beam on a symmetrical metal-cladding waveguide. The positive and negative shifts approach about 480 and 180 microm, respectively, which to our knowledge are the largest experimental results ever reported. The experiment also proves that the positive or the negative shift depends on sign of the difference between the intrinsic and radiative damping.
Optics Letters 07/2007; 32(11):1432-4. · 3.40 Impact Factor
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ABSTRACT: Optical bistability phenomenon in a single fiber ring laser employing erbium-doped fiber (EDF) as gain medium is observed in our experiment. In the EDF amplifiers, the photons of pump light cannot completely transfer into that of signal light because of various attenuation factors. This part of loss (useless pump loss) and active spontaneous emission (ASE) can both lower the small-signal gain of the EDF, and can eventually result in the bistability phenomenon. The range of this bistability has a complicated relationship with the length of the EDF, the erbium-ion doping concentration, the cavity loss and the useless loss coefficient of the pump light.
Optics Express 05/2007; 15(7):3673-9. · 3.59 Impact Factor
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ABSTRACT: A fast speed electro-optic polymer variable optical attenuator (VOA) is fabricated by utilizing cascaded attenuated-total-reflection technique. The proposed VOA demonstrates high dynamic range and low driving voltage. An ∼ 200 ns response time of the device is obtained, and other measured parameters include a dynamic range up to 24.1 dB, a driving voltage of 39.6 V, and an insertion loss of 1.02 dB.
Applied Physics Letters 04/2007; 90(15):151124-151124-3. · 3.84 Impact Factor
