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Showing papers on "Four-wave mixing published in 2009"


Journal ArticleDOI
TL;DR: Using phase control between four- wave mixing (FWM) and six-wave mixing (SWM) channels in a four-level atomic system, temporal and spatial interferences between these two nonlinear optical processes are demonstrated.
Abstract: Using phase control between four-wave mixing (FWM) and six-wave mixing (SWM) channels in a four-level atomic system, we demonstrate temporal and spatial interferences between these two nonlinear optical processes. Efficient and coexisting FWM and SWM signals are produced in the same electromagnetically induced transparency window via atomic coherence. The temporal interference has a femtosecond time scale corresponding to the optical transition frequency. Such studies of intermixing between different order nonlinear optical processes with a controllable phase delay can have important applications in high-precision measurements, coherence quantum control, and quantum information processing.

208 citations


Journal ArticleDOI
TL;DR: In this article, a nonlinear optical process may enhance pulse compression and storage, and that information about the nonlinear process itself may be stored coherently, and a pulse storage scheme in hot atomic rubidium vapour, in which a four-wave mixing normal mode is stored using a double configuration.
Abstract: Digital signal processing, holography, and quantum and classical information processing rely heavily upon recording the amplitude and phase of coherent optical signals. One method for achieving coherent information storage makes use of electromagnetically induced transparency. Storage is achieved by compressing the optical pulse using the steep dispersion of the electromagnetically induced transparency medium and then mapping the electric field to local atomic quantum-state superpositions. Here we show that nonlinear optical processes may enhance pulse compression and storage, and that information about the nonlinear process itself may be stored coherently. We report on a pulse storage scheme in hot atomic rubidium vapour, in which a four-wave-mixing normal mode is stored using a double- configuration. The entire (broadened) waveform of the input signal is recovered after several hundred microseconds (1/e time of about 120 s), as well as a new optical mode (idler) generated from the four-wave-mixing process.

149 citations


Journal ArticleDOI
TL;DR: Efficient, low power, continuous-wave four-wave mixing in the C-band is demonstrated using a high index doped silica glass micro ring resonator having a Q-factor of 1.2 million, and theoretically that the characteristic low dispersion enables phase-matching over a tuning range > 160 nm.
Abstract: We demonstrate efficient, low power, continuous-wave four-wave mixing in the C-band, using a high index doped silica glass micro ring resonator having a Q-factor of 1.2 million. A record high conversion efficiency for this kind of device is achieved over a bandwidth of 20nm. We show theoretically that the characteristic low dispersion enables phase-matching over a tuning range > 160nm.

147 citations


Journal ArticleDOI
TL;DR: In this paper, two excitation beams of frequencies ω 1 and ω 2 are used to induce nonlinear polarizations at the junction of a particle dimer, leading predominantly to second-harmonic generation, sum frequency generation, and four-wave mixing.
Abstract: We investigate the nonlinear optical properties of gold nanoparticle pairs. Two excitation beams of frequencies ω1 and ω2 are used to induce nonlinear polarizations at the junction of a particle dimer. Nonlinearities of the second and third order can be controllably induced as a function of the dimer geometry, leading predominantly to second-harmonic generation (SHG), sum frequency generation (SFG) and four-wave mixing (4WM). Due to their center symmetry, dimers with identical particle diameters give rise to a very weak second-order response, without affecting the third-order response. Therefore, a sharp probe functionalized with a symmetric metal dimer acts as a nanoscale photon source emitting narrow-band photons of frequency 2ω1 − ω2. We demonstrate that this source can be employed as a near-field optical probe for high-resolution fluorescence imaging.

142 citations


Journal ArticleDOI
TL;DR: Extra spectral sidebands with out-of-phase intensity variation between the polarization resolved soliton spectra was firstly observed, which was identified to be caused by the energy exchange between the two soliton polarization components.
Abstract: We report on the experimental evidence of four wave mixing (FWM) between the two polarization components of a vector soliton formed in a passively mode-locked fiber laser. Extra spectral sidebands with out-of-phase intensity variation between the polarization resolved soliton spectra was firstly observed, which was identified to be caused by the energy exchange between the two soliton polarization components. Other features of the FWM spectral sidebands and the soliton internal FWM were also experimentally investigated and numerically confirmed.

131 citations


Journal ArticleDOI
TL;DR: Broadband, cascaded four-wave mixing parametric oscillation in the anomalous group-velocity dispersion regime of a high-Q silica microsphere with an overall bandwidth greater than 200 nm is experimentally demonstrated.
Abstract: We analyze the process of cascaded four-wave mixing in a high-Q microcavity and show that under conditions of suitable cavity-mode dispersion, broadband frequency combs can be generated. We experimentally demonstrate broadband, cascaded four-wave mixing parametric oscillation in the anomalous group-velocity dispersion regime of a high-Q silica microsphere with an overall bandwidth greater than 200 nm.

129 citations


Journal ArticleDOI
TL;DR: Evidence that the process of four wave mixing is responsible for unidirectional blue light generation and that the phase matching conditions along a light-induced waveguide determine the direction and divergence of the blue light is presented.
Abstract: We investigate frequency up-conversion of low power cw resonant radiation in Rb vapour as a function of various experimental parameters. We present evidence that the process of four wave mixing is responsible for unidirectional blue light generation and that the phase matching conditions along a light-induced waveguide determine the direction and divergence of the blue light. Velocity-selective excitation to the 5D level via step-wise and two-photon processes results in a Doppler-free dependence on the frequency detuning of the applied laser fields from the respective dipole-allowed transitions. Possible schemes for ultraviolet generation are discussed.

123 citations


Journal ArticleDOI
TL;DR: Alternative methods for the calculation of four-wave-mixing signals are reviewed, in which the relevant laser pulses are incorporated into the system Hamiltonian and the driven system dynamics is simulated numerically exactly.
Abstract: “Four-wave-mixing” is the generic name for a family of nonlinear electronic and vibrational spectroscopies. These techniques are widely used to explore dissipation, dephasing, solvation, and interstate coupling mechanisms in various material systems. Four-wave-mixing spectroscopy needs a firm theoretical support, because it delivers information on material systems indirectly, through certain transients, which are measured as functions of carrier frequencies, durations, and relative time delays of the laser pulses. The observed transients are uniquely determined by the three-pulse-induced third-order polarization. There exist two conceptually different approaches to the calculation of the nonlinear polarization. In the standard perturbative approach to nonlinear spectroscopy, the third-order polarization is expressed in terms of the nonlinear response functions. As the material systems become more complex, the evaluation of the response functions becomes cumbersome and the calculation of the signals necess...

91 citations


Journal ArticleDOI
TL;DR: Spectral measurements and simulations indicate extended broadband operation is possible and broadband wavelength conversion of a 40 Gb/s return-to-zero signal using four-wave-mixing (FWM) in a dispersion engineered chalcogenide glass waveguide is demonstrated.
Abstract: We demonstrate broadband wavelength conversion of a 40 Gb/s return-to-zero signal using four-wave-mixing (FWM) in a dispersion engineered chalcogenide glass waveguide. The 6 cm long planar rib waveguide 2 μm wide was fabricated in a 0.87 μm thick film etched 350nm deep to correspond to a design where waveguide dispersion offsets the material leading to near-zero dispersion in the C-band and broadband phase matched FWM. The reduced dimensions also enhance the nonlinear coefficient to 9800 W-1km-1 at 1550 nm enabling broadband conversion in a shorter device. In this work, we demonstrate 80 nm wavelength conversions with 1.65 dB of power penalty at a bit-error rate of 10-9. Spectral measurements and simulations indicate extended broadband operation is possible.

81 citations


Journal ArticleDOI
TL;DR: In this article, the authors investigated frequency upconversion of low power cw resonant radiation in Rb vapour as a function of various experimental parameters and showed that the process of four wave mixing is responsible for unidirectional blue light generation.
Abstract: We investigate frequency up-conversion of low power cw resonant radiation in Rb vapour as a function of various experimental parameters. We present evidence that the process of four wave mixing is responsible for unidirectional blue light generation and that the phase matching conditions along a light-induced waveguide determine the direction and divergence of the blue light. Velocity-selective excitation to the 5D level via step-wise and two-photon processes results in a Doppler-free dependence on the frequency detuning of the applied laser fields from the respective dipole-allowed transitions. Possible schemes for ultraviolet generation are discussed.

81 citations


Journal ArticleDOI
TL;DR: High-resolution near-field imaging and spectroscopy using the nonlinear optical response of a gold nanoparticle pair as an excitation photon source for fluorescence and extinction imaging is demonstrated.
Abstract: We demonstrate high-resolution near-field imaging and spectroscopy using the nonlinear optical response of a gold nanoparticle pair as an excitation photon source. Femtosecond pulses of frequencies omega(1) and omega(2) are used to induce a nonlinear polarization at the four wave mixing (4WM) frequency 2omega(1) - omega(2) in the junction of the nanoparticle dimer. The nonlinear response leads to localized photon emission, which is employed as an excitation source for fluorescence and extinction imaging. The principle of this imaging technique is demonstrated for samples of fluorescent nanospheres and tubular J-aggregates.

Journal ArticleDOI
TL;DR: It is demonstrated that both a larger FWM conversion efficiency and an increased FWM bandwidth can be achieved in these waveguide as compared to dispersive PhC waveguides.
Abstract: In this paper, we investigate both analytically and numerically four-wave mixing (FWM) in short (80 microm) dispersion engineered slow light photonic crystal waveguides. We demonstrate that both a larger FWM conversion efficiency and an increased FWM bandwidth (approximately 10 nm) can be achieved in these waveguides as compared to dispersive PhC waveguides. This improvement is achieved through the net slow light enhancement of the FWM efficiency (almost 30dB as compared to a fast nanowire of similar length), even in the presence of slow light increased linear and nonlinear losses, and the suitable dispersion profile of these waveguides. We show how such improved FWM operation can be advantageously exploited for designing a compact 2R and 3R regenerator with the appropriate nonlinear power transfer function.

Journal ArticleDOI
TL;DR: In this paper, the underlying physics of the generation and detection of terahertz (THz) waves in gases are described, and the resulting pressure dependence of the THz radiation is explored in detail.
Abstract: The underlying physics of the generation and detection of terahertz (THz) waves in gases are described. The THz wave generation process takes place in two steps: asymmetric gas ionization by two-frequency laser fields, followed by interaction of the ionized electron wave packets with the surrounding medium, producing an intense ‘echo’ with tunable spectral content. In order to clarify the physical picture at the moment of ionization, the laser–atom interaction is treated through solution of the time-dependent Schrodinger equation, yielding an ab initio understanding of the release of the electron wave packets. The second step, where the electrons interact with the surrounding plasma is treated analytically. The resulting pressure dependence of the THz radiation is explored in detail. The THz wave detection process is shown to be the result of four-wave mixing, leading to analytical expressions of the signal obtained which allow for improved optimization of systems that exploit these effects.

Journal ArticleDOI
TL;DR: In this paper, the authors demonstrate extremely efficient four-wave mixing with gains greater than 100 at microwatt pump powers and signal-to-idler conversion of 50% in Rb vapor confined to a hollow-core photonic band-gap fiber.
Abstract: We demonstrate extremely efficient four-wave mixing with gains greater than 100 at microwatt pump powers and signal-to-idler conversion of 50% in Rb vapor confined to a hollow-core photonic band-gap fiber. We present a theoretical model that demonstrates such efficiency is consistent with the dimensions of the fiber and the optical depths attained. This is, to our knowledge, the largest four-wave mixing gain observed at such low total pump powers and the first demonstrated example of four-wave mixing in an alkali-metal vapor system with a large ($\ensuremath{\sim}30\text{ }\text{ }\mathrm{MHz}$) ground state decoherence rate.

Journal ArticleDOI
TL;DR: In this article, a multi-wavelength erbium-doped fiber laser (EDFL) was demonstrated using a piece of a bismuth-based EDF in a simple ring resonator.
Abstract: Multi-wavelength erbium-doped fiber laser (EDFL) is demonstrated using a piece of a bismuth-based erbium-doped fiber (Bi-EDF) in a simple ring resonator. The proposed EDFL is able to generate up to 17 lines with a constant channel spacing of 0.41 nm at 1615.5 nm region using only a piece of 215 cm long of Bi-EDF as both linear and nonlinear gain medium. However, the number of lines reduces to two with the use of 49 cm long of Bi-EDF. The multi-wavelength generation is due to oscillating Bi-EDF laser lines which interacts each other to create new photons at other frequency via four-wave mixing process. The multi-wavelength EDFL is stable at room temperature and also compact due to use of only a very short length of gain medium.

Journal ArticleDOI
TL;DR: This work reports the first experimental observation of four-wave mixing (FWM) in single-walled carbon nanotubes (SWCNTs) deposited on a Dshaped fiber using a 5-centimeter-long CNT-deposited D-shaped fiber.
Abstract: We report the first experimental observation of four-wave mixing (FWM) in single-walled carbon nanotubes (SWCNTs) deposited on a D-shaped fiber. FWM-based tunable wavelength conversion of a 10 Gb/s non-return-to-zero signal is demonstrated using a 5-centimeter-long CNT-deposited D-shaped fiber. A power penalty of 4 dB power is obtained in the 10 Gb/s bit-error-rate measurements.

Journal ArticleDOI
TL;DR: In this paper, the authors theoretically investigate the dually dressed electromagnetically induced transparency, and the multidressed four-wave mixing (FWM) and six-wave blending (SWM) processes in an inverted-$Y$-type atomic system with Zeeman sublevels.
Abstract: We theoretically investigate the dually dressed electromagnetically induced transparency, and the multidressed four-wave mixing (FWM) and six-wave mixing (SWM) processes in an inverted-$Y$-type atomic system with Zeeman sublevels. The results show that the Zeeman degeneracy of the dark states can be lifted by the dressing field as its intensity is increased. Moreover, the derived analytical expressions indicate that one can, for example, selectively create secondary dark states on the multi-Zeeman-sublevel dark states (by tuning the coupling field), distinguish two different types of dark states generated in two FWM processes (by properly controlling the coupling field intensity), and selectively enhance multi-FWM signals coming from various paths consisting of split Zeeman sublevels (by tuning the dressing field). The SWM signals can be either enhanced or suppressed by controlling the dressing field.

Journal ArticleDOI
TL;DR: In this article, two approaches to multitone seeding of high-power ytterbium-doped amplifiers using a symbolic and numerical code that solves a two-point boundary problem are investigated.
Abstract: In this paper, we investigate two approaches to multitone seeding of high-power ytterbium-doped amplifiers using a symbolic and numerical code that solves a two-point boundary problem. Optimization of amplifier action through wavelength separation and/or seed power ratios is considered in relation to the two most dominant nonlinear effects: stimulated Brillouin scattering (SBS) and four-wave mixing. One approach uses a large wavelength separation among the input signals, while the other approach entails that the wavelength separation is set to twice the Brillouin shift. Both techniques are shown to mitigate SBS effects, although for the latter case, four-wave mixing sidebands can carry a substantial amount of power.

Journal ArticleDOI
TL;DR: In this paper, the power dependences of enhancement and suppression in four-wave mixing (FWM) processes were investigated. But the power dependence on the interference was not investigated.
Abstract: We report our observations of enhancement and suppression between two competing four-wave mixing (FWM) processes. The results show the evolution of the dressed effects (from pure enhancement into pure suppression) in the degenerate FWM processes. Moreover, due to induced atomic coherence in the system, there exist different interplays between these two FWM processes via different detuning parameters. In addition, the power dependences of enhancement and suppression are studied. Theoretical calculations are carried out, which are in good agreement with the experimental observations.

Journal ArticleDOI
TL;DR: Dual color four-wave-mixing (FWM) microscopy is used to spatially resolve the third-order optical response from individual carbon nanotubes, showing that the signal from individual SWNTs is dominated by the electronic response.
Abstract: Dual color four-wave-mixing (FWM) microscopy is used to spatially resolve the third-order optical response from individual carbon nanotubes. Good signal-to-noise is obtained from single-walled carbon nanotubes (SWNT) sitting on substrates, when the excitation beams are resonant with electronic transitions of the nanotube, by detecting the FWM response at the anti-Stokes frequency. Whereas the coherent anti-Stokes (CAS) signal is sensitive to both electronic and vibrational resonances of the material, it is shown that the signal from individual SWNTs is dominated by the electronic response. The CAS signal is strongly polarization dependent, with the highest signals found parallel with the enhanced electronic polarizibility along the long axis of the SWNT.

Journal ArticleDOI
TL;DR: The observation of quantum correlations on light produced using all four of these systems, regardless of their substructure, suggests that it should be possible to use other systems with similar level structures in order to produce narrow frequency, non-classical beams at a particular wavelength.
Abstract: We present experimental results showing that quantum correlated light can be produced using non-degenerate, off-resonant, four-wave mixing (4WM) on both the D1 (795 nm) and D2 (780 nm) lines of (85)Rb and (87)Rb, extending earlier work on the D1 line of (85)Rb. Using this 4WM process in a hot vapor cell to produce bright twin beams, we characterize the degree of intensity-difference noise reduction below the standard quantum limit for each of the four systems. Although each system approximates a double-lambda configuration, differences in details of the actual level structure lead to varying degrees of noise reduction. The observation of quantum correlations on light produced using all four of these systems, regardless of their substructure, suggests that it should be possible to use other systems with similar level structures in order to produce narrow frequency, non-classical beams at a particular wavelength.

Journal ArticleDOI
TL;DR: In this article, the real transparency of four-wave mixing (FWM) in semiconductor optical amplifiers to modulation formats involving intensity, phase, and polarization multiplexing was investigated.
Abstract: We experimentally investigate the real transparency of four-wave mixing (FWM) in semiconductor optical amplifiers to modulation formats involving intensity, phase, and polarization multiplexing. We exploit two different FWM polarization-independent schemes (that make use of two pumps) to wavelength-convert 40 Gb/s single-polarization and 80 Gb/s polarization-multiplexed signals in case of both nonreturn-to-zero ON -OFF keying (NRZ-OOK) and NRZ differential phase-shift keying modulation formats. We found that, although FWM conversion is transparent to modulation formats employing phase and intensity, polarization-multiplexed signals pose serious limitations to all-optical processing transparency.

Journal ArticleDOI
TL;DR: In this article, numerical simulations using the split-step Fourier method are presented, showing consistency with experimental observations, showing that fiber-optical parametric amplifier can be reduced by 16 dB by decreasing the fiber length from 340 to 50 m, and increasing the pump power to maintain the gain at 20 dB.
Abstract: Four-wave-mixing crosstalk in a fiber-optical parametric amplifier has been reduced by 16 dB by decreasing the fiber length from 340 to 50 m, and increasing the pump power to maintain the gain at 20 dB. In this letter, numerical simulations using the split-step Fourier method are presented, showing consistency with experimental observations.

Journal ArticleDOI
TL;DR: In this article, the authors investigated the four-wave mixing (FWM) signal from gold nanorods (NRs) using two synchronized lasers and its potential applications in bioimaging.
Abstract: The current work investigates the four-wave mixing (FWM) signal from gold nanorods (NRs) using two synchronized lasers and its potential applications in bioimaging. Using the lightning rod model, we show that the strongest FWM occurs when the pump laser wavelength is tuned to be resonant with the longitudinal plasmon resonance wavelength of NR. The calculation is experimentally demonstrated by comparing the intensities of FWM from NRs with different plasmon resonance wavelengths. The FWM signal is further found to be enhanced by aggregation of NRs and is strongly dependent on pulse width. The FWM intensity from NRs is ∼39 times stronger than the coherent anti-Stokes Raman scattering intensity from melamine beads. This plasmon-resonance-enhanced FWM signal enables NRs to be used as a nonlinear optical (NLO) imaging probe.

Journal ArticleDOI
TL;DR: In this article, a coherent superposition of a multiband octave-spanning spectrum obtained by highly nondegenerate cascaded four-wave mixing of femtosecond pulses in bulk isotropic nonresonant media is presented.
Abstract: We present a technique to synthesize high-power single-cycle pulses in the visible and ultraviolet ranges by coherent superposition of a multiband octave-spanning spectrum obtained by highly nondegenerate cascaded four-wave mixing of femtosecond pulses in bulk isotropic nonresonant media. The generation of coherent spectra spanning over two octaves in bandwidth is experimentally demonstrated using a thin fused silica slide. Full characterization of the intervening multicolored fields using frequency-resolved optical gating, where multiple cascaded orders have been measured simultaneously, supports the possibility of direct synthesis of near-single-cycle 2.2 fs visible-uv pulses without recurring to complex amplitude or phase control, which should enable many applications in science and technology.

Journal ArticleDOI
TL;DR: The nonlinear optical properties of tetrasulfonated copper phthalocyanine dissolved in dimethyl sulfoxide solution are investigated by using a new time-resolved pump-probe system with phase object based on the PO Z-scan technique and the standard pump-Probe system.
Abstract: A new time-resolved pump-probe system with phase object, which is based on the PO Z-scan technique and the standard pump-probe system, is presented. This new method can simultaneously investigate the dynamic of nonlinear absorption and refraction conveniently. On the other hand, both degenerate and nondegenerate pump and probe beams in any polarization states can be used in this system. The nonlinear optical properties of tetrasulfonated copper phthalocyanine dissolved in dimethyl sulfoxide solution are investigated by using this system.

Journal ArticleDOI
TL;DR: A compact, easy to align, and passively phase-stabilized setup for recording two-dimensional electronic spectra in three different phase-matching directions in the boxcar geometry is reported.
Abstract: We report a compact, easy to align, and passively phase-stabilized setup for recording two-dimensional (2D) electronic spectra in three different phase-matching directions in the boxcar geometry. Passive phase stabilization is achieved by a diffractive optical element, the use of refractive optics for introducing pulse delays, and the use of common optics for all pulses. Representative 2D spectra correlating single- and double-quantum coherences in a molecular aggregate are presented.

Journal ArticleDOI
01 Nov 2009-Optik
TL;DR: In this paper, a channel allocation method based on optical Golomb ruler (OGR) that allows reduction of the FWM effect while maintaining bandwidth efficiency along with the algorithms has been presented in a very high-capacity, long-haul optical communication systems can be designed by wavelength division multiplexing (WDM) of high-bit-rate channels and by using erbium-doped fiber amplifiers (EDFAs) to periodically compensate the fiber loss.

Journal ArticleDOI
TL;DR: In this paper, a chalcogenide optical fiber of special design is proposed to convert a short-wavelength infrared radiation (around 2 mum) up to a second transparency window of atmospheric air (around 4.5 mu m) by degenerate four-wave mixing.
Abstract: A chalcogenide optical fiber of special design is proposed to convert a short-wavelength infrared radiation (around 2 mum) up to a second transparency window of atmospheric air (around 4.5 mu m) by degenerate four-wave mixing. The fiber supports a small core surrounded by three large air holes. The zero-dispersion wavelength is shifted down to 2 mum in this fiber by properly tailoring the fiber core. We demonstrate by solving the nonlinear Schrodinger equation that efficient wavelength-conversion can be obtained by pumping the fiber with a Tm:SiO2 pulsed fiber laser.

Journal ArticleDOI
TL;DR: A novel intracavity frequency modulation scheme in a tunable, picosecond optical parametric oscillator (OPO) allows for real time subtraction of the interfering background signal in coherent Raman imaging, yielding images with purely chemical contrast.
Abstract: We present a novel intracavity frequency modulation scheme in a tunable, picosecond optical parametric oscillator (OPO). The OPO signal wavelength can be modulated with a depth of more than 10 nm at a rate of 38 MHz (one half its repetition rate). We discuss the design and construction of the light source and its application to the recently-developed frequency modulation coherent anti-Stokes Raman scattering (FM-CARS) and stimulated Raman scattering (SRS) techniques. The new light source allows for real time subtraction of the interfering background signal in coherent Raman imaging, yielding images with purely chemical contrast.