Bulletin of the American Physical Society
APS March Meeting 2011
Volume 56, Number 1
Monday–Friday, March 21–25, 2011; Dallas, Texas
Session J20: Optoelectronic Devices & Applications |
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Sponsoring Units: FIAP Chair: Patrick Folkes, Army Research Laboratory Room: D168 |
Tuesday, March 22, 2011 11:15AM - 11:27AM |
J20.00001: Scanning Ladar: Spatial Imaging Performance Through Turbulence Mazen Nairat, David Volez, Srinivasu Pudi The performance of scanning laser radar is studied for generating two-dimension spatial images at long ranges. Performance is described in terms of the Modulus Transfer Function (MTF). A simple analytic expression for the MTF associated with wave front tilt caused by propagation through atmospheric turbulence is explicitly derived. The derivation includes consideration of the influence of the Fresnel length. A physical optics simulation is employed to demonstrate the applicability of the MTF approach. The results are compatible with theoretical expressions that describe the image. [Preview Abstract] |
Tuesday, March 22, 2011 11:27AM - 11:39AM |
J20.00002: Stimulated Terahertz Smith-Purcell Radiation in Planar Gunn Diodes Alexey Belyanin, Don D. Smith We propose a room-temperature semiconductor source of coherent narrowband Smith-Purcell radiation (SPR) in the spectral range of 0.1-1.2 THz. Spontaneous SPR in semiconductors has been observed at low temperature with very low power. Practical vacuum SPR devices utilize a pre-bunched electron beam to achieve the stimulated mode of operation. However, electron bunches quickly dissipate in semiconductors. We propose to utilize the Gunn instability to form stable charge bunches (Gunn domains) that enable semiconductor sources of stimulated SPR. The device is a planar Gunn diode with a thin dielectric spacer layer and metallic grating deposited on the drift region. The SPR frequency is determined by the domain velocity and the grating period. In contrast to conventional Gunn diodes, the frequency is not limited by the transit time. Our calculations show that technologically relevant power density levels (1-100 nW per micrometer of device width) may be achieved by this method. [Preview Abstract] |
Tuesday, March 22, 2011 11:39AM - 11:51AM |
J20.00003: Correlated photon fluctuations at the onset of first-order optical coherence Patrick Folkes We report the observation of correlated photon fluctuations over a narrow range of current at threshold of an interband cascade laser using single-detector photon noise measurements. The correlated photon noise is manifested by large fluctuations in the low-frequency photon noise spectral density at certain discrete frequencies which are sensitive to the laser gain characteristics. We observe the concurrent emergence and growth of the lasing mode over the same current range indicating that the correlated photon noise provides evidence of the occurrence of a change in the photon fluctuation statistics and the onset of first-order coherence in the laser emission. [Preview Abstract] |
Tuesday, March 22, 2011 11:51AM - 12:03PM |
J20.00004: Self Generation of Chaos From Electrical Solitons Ozgur Yildirim, Donhee Ham The nonlinear transmission line (NLTL) is a structure that can generate electrical solitons of subpicosecond duration. As an autonomous soliton generator utilizing the NLTL, thus far, only periodic electrical soliton oscillators have been reported. These circuits self generate a periodic train of solitons, where an amplifier with a saturable absorber prevents the generation of multiple solitons and hence their nonlinear collisions. However, if the amplifier encourages the generation of multiple solitons and their collisions, the system can attain chaos, because the position of the soliton modulates after each collision, disrupting the periodicity. In this work, for the first time, we experimentally demonstrate such a chaotic system. Our circuit self generates an aperiodic signal, which has a continuous spectral distribution. We confirm its chaotic behavior by calculating the largest Lyapunov exponent, and show that the dimensionality of the generated chaos is high (d$>$3) by performing a false-nearest-neighbors analysis. Moreover, we explicitly measure the route from periodic soliton oscillation to chaotic oscillation via decreasing the time constant of the saturable absorber, showing the effect of soliton collisions on period-doubling bifurcations and finally the creation of chaos. [Preview Abstract] |
Tuesday, March 22, 2011 12:03PM - 12:15PM |
J20.00005: Harmonic Bloch and dipole oscillations and their transition in elliptical optical waveguide arrays Yun San Chan, Ming Jie Zheng, Kin Wah Yu We have studied harmonic oscillations in an elliptical optical waveguide array in which the couplings between neighboring waveguides are varied in accord with a Kac matrix so that the propagation constant eigenvalues can take equally spaced values. As a result, the long-living optical Bloch oscillation (BO) and dipole oscillation (DO) are obtained. Moreover, when a linear gradient in the propagation constant is applied, we achieve a switching from DO to BO and vice versa by ramping up or down the gradient profile [1]. The various optical oscillations as well as their switching are investigated by field evolution analysis and confirmed by Hamiltonian optics. The equally spaced eigenvalues in the propagation constant allow viable applications in transmitting images, switching and routing of optical signals. \\[4pt] [1]. M. J. Zheng, Y. S. Chan and K. W. Yu, J. Opt. Soc. Am. B 27, 1299 (2010). [Preview Abstract] |
Tuesday, March 22, 2011 12:15PM - 12:27PM |
J20.00006: Bloch-dipole-Zener Oscillations in Binary Parabolic Optical Waveguide Arrays Ming Jie Zheng, Yun San Chan, Kin Wah Yu We have studied the propagation and Zener tunneling of light in the binary parabolic optical waveguide arrays (BPOWA) consisting of two evanescently coupled dissimilar optical waveguides. BPOWA attains two minibands with a gap at the zone edge due to Bragg reflections. Various superposition of optical oscillations and Zener tunneling are identified for different parameters on the phase diagram. In particular, both Bloch-Zener oscillation [1] and Bloch-dipole-Zener oscillation are obtained in the BPOWA by the field-evolution analysis. The research results may have potential applications in optical splitting and waveguiding devices and shed light on the coherent phenomena in lattice structures [2]. \\[4pt] [1] F. Dreisow, A. Szameit, M. Heinrich, T. Pertsch, S. Nolte, A. Tunnermann, and S. Longhi, ``Bloch-Zener Oscillations in Binary Superlattices,'' Phys. Rev. Lett. 102, 076802 (2009). \\[0pt] [2] M. J. Zheng, G. Wang, and K. W. Yu, ``Tunable Hybridization at Mid Zone and Anomalous Bloch-Zener Oscillations in Optical Waveguide Ladders,'' Opt. Lett. (in press). [Preview Abstract] |
Tuesday, March 22, 2011 12:27PM - 12:39PM |
J20.00007: Cavity phase matching for a high efficient sheet optical parametric oscillator Z.D. Xie, X.J. Lv, S.N. Zhu Cavity phase matching (CPM) was first proposed in the early days in nonlinear optics by J. A. Armstrong, N. Bloembergen, J. Ducuing and P. S. Pershan in theory in 1962 as one of the three protocols to realize phase matching in nonlinear medium. The other two protocols have been developed into the well-known quasi-phase matching (QPM) technique. CPM has equivalent capability to compensate for the phase mismatching as QPM in principle and people has been attempting to achieve CPM in several kinds of semi-conductor materials. However, there is no convincing experimental realization up to date. In the work, we manufactured, for the first time, a CPM optical parametric oscillator (OPO) which consisted of a 217$\mu$m thick KTP crystal sheet whose two surfaces were optically coated for the resonance recirculation of signal and idler. The sheet OPO could emitted the near-frequency-degenerate signal and idler beams in near-infrared region with a quasi-continuously tunable frequency difference ranging from 0.35 to 26.1\textit{THz}. This mini-device showed the high slope efficiency up to 22{\%}, and as well the unique spectral and spatial features, like single-longitudinal-mode, single-spatial-mode, narrow linewidth, etc. [Preview Abstract] |
Tuesday, March 22, 2011 12:39PM - 12:51PM |
J20.00008: Variation of Losses with Detuning in Bragg Gratings Sergiy Mokhov, Derrek Drachenberg, George Venus, Boris Zeldovich, Leonid Glebov The optical losses due to small scattering and absorption in Bragg gratings are proportional to the loss coefficient, and also depend on the integral of optical power over grating length. At different resonant conditions this integral of stored optical power inside a grating differs from the product of power by length for transmitted beams far from resonance. We have found an analytical expression for the relative value of this integral in the case of a uniform grating. If it equals unity for a beam propagating out of resonance, then for a grating in Bragg resonance with reflectance of 99{\%} it equals 0.332 due to exponential decay of reflected and transmitted power inside the grating and grows up to 2.027 near the first zero of the reflection spectrum due to increased resonant capacity of the grating similar to a Fabry-Perot resonator. Also, we have found analytically that in the case of spatially modulated grating losses with Bragg period the odd-functional term will be present in the expression for relative losses in addition to the term for averaged losses. We have measured this variation of losses in volume Bragg grating at a small incidence angle, and in this case can resolve the incident and reflected beams and precisely measure the power balance in the experimental setup, and the results show good agreement with theory. [Preview Abstract] |
Tuesday, March 22, 2011 12:51PM - 1:03PM |
J20.00009: Temperature dependence of polaritons in ZnO based hybrid micro-cavity Ryoko Shimada, Sankar Davuluri, Hadis Markoc, Arup Neogi We have studied the temperature dependence of cavity polaritons in bulk ZnO-based hybrid microcavities. The bulk ZnO-based micro cavity is formed by 36 pairs of AlGaN/(Al)GaN distributed Bragg reflector at the bottom of (lambda)/4 thick ZnO cavity and eight pairs of SiO2/SiN DBR as top mirror. Shift in exciton resonances with temperature resulted in shift in the energy levels of upper and lower polariton modes. The magnitude of observed energy shifts in polariton modes is dependent on the angle at which photoluminescence is collected. It can be possible to obtain either a upper or lower polariton mode that is stable over a long range of temperature by selectively collecting the polaritons modes emitted at a particular angle. The temperature dependent carrier dynamics of the upper or lower polariton mode has been studied by time resolved spectroscopy. [Preview Abstract] |
Tuesday, March 22, 2011 1:03PM - 1:15PM |
J20.00010: Study of the Coherent Phonon-Polariton effect on the Terahertz pulse generation in $<$110$>$ ZnTe crystal Chien-Ming Tu, Jeng-Chung Chen, Cheng-Chung Chi We report a study of the wave form and spectrum of the THz radiation generated by illuminating $<$110$>$ ZnTe crystal with femto-second optical pulses of 750 nm in wavelength. The co-linearly measured wave form consists of a main W-shaped THz pulse and a trailing quasi monochromatic damped oscillation (QMDO) with a duration of several tens of pico-seconds. In Fourier-transformed spectrum of the measured THz waveform, there are two peaks, one centered at 0.6 THz and the other one at 2.7 THz, which correspond to the main THz pulse and the QMDO respectively. Our calculation of the THz pulse generated by the optical pulse indicates that the QMDO is caused by the phase matching of the optical pulse and the coherent phonon-polariton in ZnTe. We observe that, by increasing the optical pulse width, the duration of the trailing QMDO shrinks in time domain, and the amplitude of the phase-matching component also reduces, both of which are consistent with our calculations. There remain some subtle differences between the experimental results and the theoretical calculations, the origin of which will be discussed. [Preview Abstract] |
Tuesday, March 22, 2011 1:15PM - 1:27PM |
J20.00011: Accurate Formulation and Numerical Calculation of Faraday, Magnetic Circular Dichroism (MCD) and Kerr Effect of Light in Magnetized Cubic Crystal Jin T. Wang, Sean Hall, Yi Zhen, Dong-Sheng Guo Faraday, magnetic circular dichroism and Kerr effects are three important magneto-optic effects. They are significant in fundamental sciences and applications. Presently, scientists in this field believed that Faraday and Kerr effects are caused by the difference in real parts of the refractive indices of the magnetic crystal for left-and right-circularly polarized light and the magnetic circular dichroism is caused by the difference in the imaginary parts of the refractive index (absorption) of the magnetic crystal for left-and right-circularly polarized light. However, the derived equations for these effects are approximated only. In our paper we obtained accurate formulations for these effects and found that there are mistakes in the present conclusions with respect to the above mentioned these effects. The precise equations, conclusions from our derivation and the results of numerical calculation are presented. [Preview Abstract] |
Tuesday, March 22, 2011 1:27PM - 1:39PM |
J20.00012: Quantum cascade laser with low threshold and high characteristic temperature T$_{0}>$ 300K at $\sim $ 14 $\mu $m Xue Huang, William Charles, Claire Gmachl High-performance quantum cascade (QC) lasers with wavelength in 4 $\sim $ 12 $\mu $m range are widely used in trace gas sensing. However, lack of high performance for longer wavelength in the 12 $\sim $ 16 $\mu $m range, where exist the strongest absorption lines of BTEX (benzene, toluene, ethylbenzene, and xylenes) and Uranium Hexafluoride, prohibits QC laser applications in sensing these important gases. The QC laser emitting at $\sim $ 14 $\mu $m we investigate here is based on a diagonal-transition design. The depletion of the lower laser state is achieved by a one-phonon-continuum scheme instead of the widely used ``continuum'' lower mini-bands in existing long-wavelength lasers. This scheme reduces LO scattering from the upper laser state, the leakage from the injector and thermal back-filling to the lower laser state, thus attaining population inversion efficiently. The laser shows low threshold (J$_{th}$ =2.4 kA/cm$^{2}$ for a 1.97-mm-long laser at room temperature), and a high characteristic temperature T$_{0}$ =309K fitted from $\mbox{J}_{\mbox{th}} \mbox{(T) = J}_0 e^{\mbox{T/T}_0 }$ , which is comparable with the record highest characteristic temperature. The peak power is 1.4W at 80K and 0.25W at 300K. [Preview Abstract] |
Tuesday, March 22, 2011 1:39PM - 1:51PM |
J20.00013: The effect of energy density on laser flyer velocity H.R. Brierley, T.A. Vine Laser driven flyers are produced on the interaction of a laser pulse with a thin film of metal. When an Nd:YAG laser is focussed through a fused silica substrate onto a 5 micron layer of aluminium, a fraction of the metal is ablated. This causes the remaining aluminium to be punched from the film and launched as a discrete flyer. By varying the energy of the incident laser pulse, the velocity of the resulting flyer is changed. The Nd:YAG laser beam was spatially filtered to remove higher order modes. This improved the beam quality and reduced the focal spot diameter. The resulting higher energy densities led to faster flyer velocities for a given pulse energy. [Preview Abstract] |
Tuesday, March 22, 2011 1:51PM - 2:03PM |
J20.00014: Spatially-sculpted aberrated optical tweezers for delivery of nanoparticles onto cells Shivaranjani Shivalingaiah, Suyash Chhajed, Samarendra Mohanty Nanoparticles (NP) are emerging as photochemical and photothermal agents for delivery of drugs and heat onto the targeted cells. Here, we report spatially-sculpting of transverse potential landscape by introducing aberration in the optical tweezers beam for delivery of therapeutic NP on to the prostate cancer PC3 cells. A tunable Ti-Sapphire laser beam was focused to a diffraction limited spot by use of a high numerical aperture microscope objective for optical trapping. A cylindrical lens was used to create the beam profile astigmatic, which led to spatially extended potential landscape. In order to facilitate transport of NP, Comatic potential was created by tilting of the astigmatic beam with respect to the optic axis. NPs were attracted towards the potential minima, transported along the major axis of the elliptic spot and ejected out along the direction having lower stiffness. The Carbon NPs as well as Poly Lactic-\textit{co}-Glycolic Acid NPs were efficiently transported and concentrated near the PC3 cells\textit{ in-vitro}. The direction and the speed of transport of nano-particles could be reversed by change in tilt direction and angle. Further, by utilizing the scattering force with the asymmetric gradient force, three-dimensional transport of nanoparticles was achieved. The effect of laser beam power and size / refractive index of the nano-particles on the speed of transport will be presented. [Preview Abstract] |
Tuesday, March 22, 2011 2:03PM - 2:15PM |
J20.00015: Mapping force of interaction between PLGA nanoparticle with cell membrane using optical tweezers Suyash Chhajed, Ling Gu, Homa Homayoni, Kytai Nguyen, Samarendra Mohanty Drug delivery using magnetic (Fe$_{3}$O$_{4})$ Poly Lactic-\textit{co}-Glycolic Acid (PLGA) nanoparticles is finding increasing usage in therapeutic applications due to its biodegradability, biocompatibility and targeted localization. Since optical tweezers allow non-contact, highly sensitive force measurement, we utilized optical tweezers for studying interaction forces between the Fe$_{3}$O$_{4}$-PLGA nanoparticles with prostate cancer PC3 cells. Presence of Fe$_{3}$O$_{4}$ within the PLGA shell allowed efficient trapping of these nanoparticles in near-IR optical tweezers. The conglomerated PLGA nanoparticles could be dispersed by use of the optical tweezers. Calibration of trapping stiffness as a function of laser beam power was carried out using equipartition theorem method, where the mean square displacement was measured with high precision using time-lapse fluorescence imaging of the nanoparticles. After the trapped PLGA nanoparticle was brought in close vicinity of the PC3 cell membrane, displacement of the nanoparticle from trap center was measured as a function of time. In short time scale ($<$ 30sec), while the force of interaction was within 0.2 pN, the force increased beyond 1pN at longer time scales ($\sim $ 10 min). We will present the results of the time-varying force of interactions between PLGA nanoparticles with PC3 cells using optical tweezers. [Preview Abstract] |
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