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ABSTRACT: We demonstrate experimentally that spontaneous parametric down-conversion in an AlxGa<sub>1-x</sub>As semiconductor Bragg reflection waveguide can make for paired photons highly entangled in the polarization degree of freedom at the telecommunication wavelength of 1550 nm. The pairs of photons show visibility higher than 90% in several polarization bases and violate a Clauser-Horne-Shimony-Holt Bell-like inequality by more than 3 standard deviations. This represents a significant step toward the realization of efficient and versatile self pumped sources of entangled photon pairs on-chip.
Optics Express 05/2013; 21(9):10841-9. · 3.59 Impact Factor
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ABSTRACT: We demonstrate experimentally that spontaneous parametric down-conversion in
an AlGaAs semiconductor Bragg reflection waveguide can make for paired photons
highly entangled in the polarization degree of freedom at the telecommunication
wavelength of 1550 nm. The pairs of photons show visibility higher than 90% in
several polarization bases and violate a Clauser-Horne-Shimony-Holt Bell-like
inequality by more than 3 standard deviations. This represents a significant
step toward the realization of efficient and versatile self pumped sources of
entangled photon pairs on-chip.
03/2013;
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ABSTRACT: An on-chip waveguide-based source of entangled photons capable of switching between generating time-energy entangled and hyperentangled (entangled in both time energy and polarization) photon pairs is proposed. The switching can be done all-optically by rotating the pump polarization. The source is based on multichannel phase matching in Bragg reflection waveguides achieved by engineering the Fresnel reflection of photonic bandgap claddings for differently polarized modes. Analytical results are confirmed in fully vectorial numerical simulations.
Optics Letters 09/2011; 36(18):3548-50. · 3.40 Impact Factor
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ABSTRACT: Wavelength conversion by difference frequency generation is demonstrated in domain-disordered quasi-phase-matched waveguides. The waveguide structure consisted of a GaAs/AlGaAs superlattice core that was periodically intermixed by ion implantation. For quasi-phase-matching periods of 3.0-3.8 μm, degeneracy pump wavelengths were found by second-harmonic generation experiments for fundamental wavelengths between 1520 and 1620 nm in both type-I and type-II configurations. In the difference frequency generation experiments, output powers up to 8.7 nW were generated for the type-I phase matching interaction and 1.9 nW for the type-II interaction. The conversion bandwidth was measured to be over 100 nm covering the C, L, and U optical communications bands, which agrees with predictions.
IEEE Journal of Quantum Electronics 07/2011; · 1.88 Impact Factor
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ABSTRACT: Entangled photon pair generation by spontaneous parametric downconversion in Bragg reflection waveguides is theoretically investigated. Enhanced nonlinear interaction through tight mode confinement in the waveguide results in pair generation rate up to 4×10<sup>8</sup> pairs/s/mW/nm.
Lasers and Electro-Optics (CLEO), 2011 Conference on; 06/2011
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IEEE Photon. Technol. Lett. 01/2011;
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ABSTRACT: We demonstrate experimentally the stable continuous-wave (CW) single-mode operation of Bragg reflection waveguide (BRW) lasers from 10 to 100°C. The threshold characteristics, quantum efficiency, gain, and self-heating characteristics are investigated in detail. Threefold enhancement in the optical confinement is achieved using these BRW structures for a core width two times that of their edge-emitting total internal reflection counterparts. The device shows also the high gain and characteristic temperature (~197 K) under CW operation from 10 to 100°C. The mode stability is analyzed by the calculated mode reflection spectrum, injection-current-dependent lasing spectrum, and near-field patterns.
IEEE Journal of Quantum Electronics 12/2010; · 1.88 Impact Factor
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Laser & Photonics Review 09/2010; 5(2):272 - 286. · 7.39 Impact Factor
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The Canadian Association of Physicists (CAP) Congress 2010, Toronto, Canada; 01/2010
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IEEE J. Quantum Electron. 01/2010;
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ABSTRACT: The impact of third-order nonlinearities including self-phase modulation and two-photon absorption on the efficiency of the second-harmonic generation is numerically investigated using the split-step Fourier method in phase-matched Bragg reflection waveguides. Also using the same technique, the adverse effects of group velocity mismatch and group velocity dispersion of the interacting frequencies on the efficiency of the nonlinear process are examined and contrasted for optimal sample design. Using an optimized structure, we report efficient femtosecond second-harmonic generation in monolithic AlGaAs Bragg reflection waveguides for a type II nonlinear interaction. For a 190 fs pulsed pump around 1555 nm with an average power of 3.3 mW, a peak second-harmonic power of 25.5 μW is measured in a sample with a length of 1.1 mm. The normalized conversion efficiency of the process is estimated to be 2.0×104% W−1 cm−2. Pump depletion is clearly observed when operating at the phase-matching wavelength.
Journal of the Optical Society of America B 01/2010; 27:1291-1298. · 2.18 Impact Factor
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ABSTRACT: In this letter, we demonstrate significant improvement in second-harmonic (SH) generation using matching layer enhanced Al<sub>x</sub>Ga<sub>1-x</sub>As Bragg reflection waveguide in type-I and type-II phase-matching schemes. For a 1.8-ps pulsed pump around 1550 nm with an average power of 3.3 mW, peak SH powers of 28 and 60 muW were measured in type-I and type-II interactions, respectively. The associated normalized conversion efficiencies were estimated to be 5.30 times 10<sup>3</sup>% and 1.14 times 10<sup>4</sup>% W<sup>-1</sup> middot cm<sup>-2</sup> with SH process bandwidths of 1.7- and 1.8-nm full-width at half-maximum. Waveguides with various ridge widths ranging between 2.8 and 4.8 mum with 2.17-mm length were characterized.
IEEE Photonics Technology Letters 11/2009; · 2.19 Impact Factor
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ABSTRACT: Second-harmonic generation is demonstrated in periodically intermixed GaAs/AlGaAs superlattice waveguides by Type-II phase matching. Second-harmonic powers of 2.0 muW were generated at fundamental phase matching wavelength of 1577.4 nm.
Lasers and Electro-Optics, 2009 and 2009 Conference on Quantum electronics and Laser Science Conference. CLEO/QELS 2009. Conference on; 07/2009
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ABSTRACT: We demonstrate and study a novel process for fabrication of GaAs-based self-aligned lasers based upon a single overgrowth. A lattice-matched n-doped InGaP layer is utilized for both electrical and optical confinements. Single-lateral-mode emission is demonstrated initially from an In<sub>0.17</sub>Ga<sub>0.83</sub>As double quantum well laser emitting ~980 nm. We then apply the fabrication technique to a quantum dot laser emitting ~1300 nm. Furthermore, we analyze the breakdown mechanism in our devices and discuss the limitations of index guiding in our structures.
IEEE Journal of Selected Topics in Quantum Electronics 07/2009; · 3.78 Impact Factor
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ABSTRACT: Bragg reflection waveguides (BRWs) with matching layers placed between the core and claddings are proposed and analyzed as a means of enhancing the effective second-order optical nonlinearity. The addition of matching layers to conventional BRW structures provides extra degrees of freedom, which enable further optimization to enhance the nonlinear conversion efficiency. Pertinent parameters including overlap between modal profiles of the interacting waves, the group velocity mismatch and group velocity dispersion are examined. The structures studied in this work are designed using the GaAs-Al<sub>x</sub>Ga<sub>1-x</sub> As material system. It is shown that, in comparison to phase-matched BRWs with no matching layers, the proposed structure benefits from relaxing the constraint over the phase-matched core thickness. For typical designs, it is shown that the new structure can provide over an order of magnitude enhancement in nonlinear coupling efficiency and 30% decrease in group velocity mismatch. It is also shown that the group velocity dispersion of the first and second harmonics are reduced by 10% and 52%, respectively.
IEEE Journal of Quantum Electronics 07/2009; · 1.88 Impact Factor
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C.A. Merchant,
P. Scrutton,
S. Garcia-Blanco,
C. Hnatovsky,
R.S. Taylor,
A. Garcia-Navarro,
G. Garcia,
F. Agullo-Lopez,
J. Olivares, A.S. Helmy,
J.S. Aitchison
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ABSTRACT: We report on the characterization of planar waveguides formed in the Raman-active crystal KGd(WO<sub>4</sub>)<sub>2</sub> using swift carbon, fluorine, and oxygen ion irradiation. The characterization of the waveguiding regions was performed using high-resolution microreflectivity and micro-Raman spectroscopy. The high-resolution microreflectivity measurement fully characterizes the refractive index profile of the barrier formed by amorphization of the crystal and detects other index variations not detected by the m-line technique. Raman spectroscopy measurements reveal details of the Raman properties of the crystal in the waveguiding region in relation to the rest of the sample for the different ion irradiations. Both of these measurement techniques are shown to be important for use of KGd(WO<sub>4</sub>)<sub>2</sub> in integrated Raman-active devices.
IEEE Journal of Quantum Electronics 05/2009; · 1.88 Impact Factor
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ABSTRACT: Substantial enhancement in Raman back scattering is obtained when the solution investigated is placed in the core of a hollow core photonic crystal fiber. The origin of this enhancement for liquid core waveguides is discussed. The enhancement is then used to study the Raman modes of several types of nanoparticles the Raman spectroscopy of colloidal nanoparticles in dilute solution. By employing this technique, four different stages of the synthesis ZnO nanoparticles were studied with record low pump power levels. The concentration of ZnO in the system was <1% by weight of the total mass. Also the different synthesis stages could be differentiated, and the differences between these stages could be identified through the Raman modes obtained. The concentration of nanoparticles in solution could be obtained with sensitivity for concentrations in the millimolar range. Raman modes of other nanoparticles such as CdTe have also been examined.
PhotonicsGlobal@Singapore, 2008. IPGC 2008. IEEE; 01/2009
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ABSTRACT: Continuous wave second-harmonic generation was demonstrated in quasi-phase-matched GaAs/AlGaAs superlattice-core waveguides formed by periodic intermixing. Output second harmonic powers of 950 nW were recorded. Bistability was observed when tuning either the input power or wavelength.
IEEE Lasers and Electro-Optics Society, 2008. LEOS 2008. 21st Annual Meeting of the; 12/2008
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ABSTRACT: Spatially resolved Raman spectroscopy at room temperature is used to study quantum well intermixing in GaAs:AlAs superlattice structures. Phonon modes are probed from the side facet along the [110] direction. The intermixing leads to the appearance of interfacial alloy modes and degraded the intensity of the superlattice interface (IF) modes, which can be used as a sensitive indicator of superlattice quality. These changes in the Raman spectra, along with spatially resolved photoluminescence, are used to distinguish the degree of intermixing in samples intermixed by impurity free vacancy diffusion at 850–950 ° C , and to investigate the bandgap modulation in a periodically intermixed bandgap grating fabricated using ion implantation induced disordering. The shift of the GaAs-transverse optic mode to the GaAs-like transverse optic alloy mode and the degradation of the GaAs-IF mode are shown to provide the best indication of the extent of intermixing. Due to the large contrast in the GaAs-IF mode intensity between as-grown and intermixed superlattice, using IF modes is found to be a promising route for characterizing the resolution of the superlattice bandgap grating.
Journal of Applied Physics 11/2008; · 2.17 Impact Factor
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ABSTRACT: Hollow-core photonic crystal fibers (HC-PCF) were employed for enhancing the Raman signal obtained from ZnO nanoparticles (NPs) in solution. By selectively filling the core of HC-PCF, substantial enhancement in the Raman signal was obtained. By employing this technique, four different stages in the synthesis ZnO NPs were studied with record low pump power levels. The concentration of ZnO NPs in the system was <1% by weight of the total mass. Yet, the different synthesis stages could be differentiated and identified through the Raman modes obtained. It was also demonstrated that the concentration of NPs in solution could be obtained with sensitivity in the millimolar range. This could be achieved by examining the amplitude ratios of the relevant Raman modes.
IEEE Journal of Selected Topics in Quantum Electronics 08/2008; · 3.78 Impact Factor
