Single fiber laser based wavelength tunable excitation for CRS spectroscopy

• Jue Su, Ruxin Xie, Carey Johnson, and Rongqing Hui
• received 02/20/2013; accepted 04/25/2013; posted 05/01/2013; Doc. ID 185681
• [full text: PDF (923) KB)]
• Abstract: We demonstrate coherent Raman spectroscopy (CRS) using a tunable excitation source based on a single femtosecond fiber laser. The frequency difference between the pump and the Stokes pulses was generated by soliton self-frequency shift (SSFS) in a nonlinear optical fiber. Spectra of C-H stretches of cyclohexane were measured simultaneously by stimulated Raman gain (SRG) and coherent anti-Stokes Raman scattering (CARS) and compared. We demonstrate the use of spectral focusing through pulse chirping to improve CRS spectral resolution. We analyzed the impact of pulse stretching on the reduction of the power efficiency for CARS and SRG. Due to chromatic dispersion in the fiber-optic system, the differential pulse delay is a function of Stokes wavelength. This differential delay has to be corrected when performing spectroscopy in which Stokes wavelength is scanned. Strategies of system optimization consideration are discussed in terms of practical applications.

Keywords (OCIS):

• (190.4370) Nonlinear optics : Nonlinear optics, fibers
• (300.6230) Spectroscopy : Spectroscopy, coherent anti-Stokes Raman scattering
• (300.6450) Spectroscopy : Spectroscopy, Raman
• (320.1590) Ultrafast optics : Chirping
• (190.4223) Nonlinear optics : Nonlinear wave mixing
• (180.5655) Microscopy : Raman microscopy

12345678910111213141516171819202122232425262728293031Single photon generation by pulsed laser in optomechanical system via photon blockade effect

• Liu Qiu, Lin Gan, Wei Ding, and Zhi-Yuan Li
• received 02/25/2013; accepted 04/24/2013; posted 05/02/2013; Doc. ID 185940
• [full text: PDF (3780) KB)]
• Abstract: 12345678910111213141516171819202122232425262728293031We theoretically analyzed the photon quantum statistics properties of the output field from optomechanical system driven by different pulsed lasers. Our results show that the probability of generating single-photon state at the photon blockade region is greatly dependent on properties such as the shape, area, central frequency, length and amplitude of the driving pulse. These results will give guidance to the design of the potential optimal optical pulse for generating high-performance single-photon source.

Keywords (OCIS):

• (270.5290) Quantum optics : Photon statistics
• (120.4880) Instrumentation, measurement, and metrology : Optomechanics

Three-dimensional integral equation approach to light scattering, extinction cross sections, local density of states and quasinormal modes

• Jakob Rosenkrantz de Lasson, Jesper Moerk, and Philip Kristensen
• received 03/12/2013; accepted 04/24/2013; posted 05/21/2013; Doc. ID 186855
• [full text: PDF (623) KB)]
• Abstract: We present a numerical formalism for solving the Lippmann-Schwinger equation for the electricfield in three dimensions. The formalism may be applied to scatterers of different shapes andembedded in different background media, and we develop it in detail for the specific case of sphericalscatterers in a homogeneous background medium. In addition, we show how several physicallyimportant quantities may readily be calculated with the formalism. These quantities include theextinction cross section, the total Green’s tensor, the projected local density of states and the Purcellfactor as well as the quasinormal modes of leaky resonators with the associated resonance frequenciesand quality factors. We demonstrate the calculations for the well-known plasmonic dimer consistingof two silver nanoparticles and thus illustrate the versatility of the formalism for use in modeling ofadvanced nanophotonic devices.

Keywords (OCIS):

• (000.3860) General : Mathematical methods in physics
• (240.6680) Optics at surfaces : Surface plasmons
• (290.4210) Scattering : Multiple scattering
• (050.1755) Diffraction and gratings : Computational electromagnetic methods

12345678910111213141516171819202122232425262728293031SrZn2Si2O7:Eu2+,Mn2+: A single-phased emission-tunable nano-phosphor suitable for white-light-emitting diodes

• R. Salimi, H. Sameie, A. Sabbagh Alvani, A. Sarabi, H. Eivaz Mohammadloo, F. Nargesian, M. Sabbagh Alvani, and M. Tahriri
• received 01/31/2013; accepted 04/21/2013; posted 05/07/2013; Doc. ID 184621
• [full text: PDF (1597) KB)]
• Abstract: 12345678910111213141516171819202122232425262728293031A new series of emission-tunable nano-phosphors with nominal composition of Sr0.96Zn2-xSi2O7:0.04Eu2+,xMn2+ (0≤x≤0.15) were designed and synthesized by sol-gel technique for application in white light-emitting diodes. The structural, morphological and optical properties were investigated using comprehensive characterization methods such as X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM/TEM), Energy-dispersive X-ray spectroscopy (EDX) and photoluminescence (PL) spectroscopy. The results indicate that the calcination temperature has strong effect on the crystalinity and morphology. Moreover, the calcination temperature can change grain size and micro-strain. SrZn2Si2O7:Eu2+,Mn2+ phosphors show two emission bands excited by near ultraviolet light: blue (around 480 nm) and orange-yellow (around 595 nm) emissions. These emissions are photo-physically originated from 4f65d1(2D)→4f7(8S7/2) transition of Eu2+ sensitizer ions and 4T1(4G)→6A1(6S) transition of Mn2+ activator ions, respectively. The phosphors can generate various lights with different color coordinates and relative color temperatures by properly tuning the relative ratio of the Eu2+ to Mn2+ ions through the principle of energy transfer. The energy transfer from Eu2+ to Mn2+ in SrZn2Si2O7 host matrix was confirmed by several experimental results such as the luminescence spectra, energy transfer efficiency and decay curve of the phosphors. Furthermore, the mechanism of this phenomenon was demonstrated resonant type via a dipole-quadrupole reaction and the critical distance between Eu2+ and Mn2+ ions was calculated about 10.7Å. Eventually, when the dopant content of Mn2+ is 0.09, the color coordinate of the phosphor (x=0.345, y=0.301) is close to the normal white-light and can be considered as a suitable UV-converting phosphor for white light-emitting diodes.

Keywords (OCIS):

• (160.2540) Materials : Fluorescent and luminescent materials
• (160.4760) Materials : Optical properties
• (160.6060) Materials : Solgel

Theory of microdroplet and microbubble deformation by Gaussian laser beam

• Simen Ellingsen
• received 12/12/2012; accepted 04/19/2013; posted 04/22/2013; Doc. ID 181595
• [full text: PDF (1561) KB)]
• Abstract: The theory for linear deformations of fluid microparticles in a laser beam of Gaussian profile is presented, when the beam focus is at the particle center as in optical trapping. Three different fluid systems are considered: water microdroplet in air, air microbubble in water, and a special oil-emulsion in water system used in experiments with optical deformation of fluid interfaces. We compare interface deformations of the three systems when illuminated by a wide (compared to particle radius) and narrow laser beams and analyse differences. Deformations of droplets are radically different from bubbles under otherwise identical conditions, due to the opposite lensing effect (converging and diverging, respectively) of the two; a droplet is deformed far more than a bubble, \emph{cetera paribus}. Optical contrast is found to be of great importance to the shape obtained when comparing the relatively low-contrast oil-emulsion system to that of water droplets. We finally analyse the dynamics of particle motion when the laser beam is turned on, and compare a static beam to the case of a short pulse. The very different surface tension coefficient implies a very different time scale for dynamics: microseconds for the water-air interface and tens of milliseconds for the oil-emulsion. Surface oscillations of a water microdroplet are found always to be underdamped, while those of the oil-emulsion are overdamped; deformations of a microbubble can be either, depending on physical parameters.

Keywords (OCIS):

• (240.0240) Optics at surfaces : Optics at surfaces
• (260.2110) Physical optics : Electromagnetic optics
• (350.4855) Other areas of optics : Optical tweezers or optical manipulation
• (240.6648) Optics at surfaces : Surface dynamics

Spectra, thresholds and modal fields of a kite-shaped microcavity laser

• Elena Smotrova, Victor Tsvirkun, Iryna Gozhyk, Clement Lafargue, Christian Ulysse, Melanie Lebental, and Alexander Nosich
• received 03/07/2013; accepted 04/15/2013; posted 04/30/2013; Doc. ID 186521
• [full text: PDF (1813) KB)]
• Abstract: We investigate the lasing spectra, threshold values, and emission directionalities for two-dimensional (2-D) microcavity laser with a “kite” contour. The modes polarized in the cavity plane are considered accurately using the linear electromagnetic formalism of the Lasing Eigenvalue Problem (LEP) with exact boundary and radiation conditions. We develop a numerical algorithm based on the Muller boundary integral equations discretized using the Nystrom technique which has theoretically justified and fast convergence. The influence of the deviation from the circular shape on the modal characteristics is studied numerically, demonstrating opportunities of directionality improvement together with preservation of a low threshold. These advantageous features are shown for the perturbed whispering-gallery modes of high enough azimuth orders. Other modes can display improved directivities while suffering from drastically higher threshold levels. Experiments based on planar organic microcavity lasers confirm the coexistence of Fabry-Perot like and Whispering Gallery like modes in these kite-shaped cavities and show good agreement with the predicted far-field angular diagrams.

Keywords (OCIS):

• (000.3860) General : Mathematical methods in physics
• (000.4430) General : Numerical approximation and analysis
• (140.2050) Lasers and laser optics : Dye lasers
• (140.3410) Lasers and laser optics : Laser resonators
• (140.3560) Lasers and laser optics : Lasers, ring

12345678910111213141516171819202122232425262728293031Direct Experimental Simulation of the Yang-Baxter Equation

• Chao Zheng, Jun-lin Li, Si-yu Song, and Gui Lu Long
• received 02/12/2013; accepted 03/25/2013; posted 05/02/2013; Doc. ID 185232
• [full text: PDF (580) KB)]
• Abstract: 12345678910111213141516171819202122232425262728293031Introduced in the field of many-body statistical mechanics, Yang-Baxter equation has become an important tool in a variety fields of physics. In this work, we report the first direct experimental simulation of the Yang-Baxter equation using linear quantum optics. The equality between the two sides of the Yang-Baxter equation in two dimension has been demonstrated directly, and the spectral parameter transformation in the Yang-Baxter equation is explicitly confirmed.

Keywords (OCIS):

• (030.0030) Coherence and statistical optics : Coherence and statistical optics
• (270.0270) Quantum optics : Quantum optics
• (270.5585) Quantum optics : Quantum information and processing

12345678910111213141516171819202122232425262728293031A Scalar Wigner Theory for Polarized Light in Nonlinear Kerr Media

• T. Hansson, E. Wallin, G. Brodin, and M. Marklund
• received 10/26/2012; accepted 02/10/2013; posted 05/01/2013; Doc. ID 178798
• [full text: PDF (234) KB)]
• Abstract: 12345678910111213141516171819202122232425262728293031A scalar Wigner distribution function for describing polarized light is proposed in analogy with the treatment of spin variables in quantum kinetic theory. The formalism is applied to the propagation of circularly polarized light in nonlinear Kerr media and an extended phase space evolution equation is derived along with invariant quantities. We further consider modulation instability as well as the extension to partially coherent fields.

Keywords (OCIS):

• (030.6600) Coherence and statistical optics : Statistical optics
• (190.0190) Nonlinear optics : Nonlinear optics