Showing papers on "Four-wave mixing published in 1993"
TL;DR: In this paper, a polarization-independent frequency conversion over a 1-THz range by fiber four-wave mixing is demonstrated using a polarization diversity technique, where the power of the converted light varies less than 0.2 dB.
Abstract: Polarization-independent frequency conversion over a 1-THz range by fiber four-wave mixing is demonstrated using a polarization diversity technique. The power of the converted light varies less than 0.2 dB. Bit-error-rate (BER) performance of frequency-shift-keying (FSK) direct detection at 622 Mb/s confirms the feasibility of the technique. >
160 citations
TL;DR: In this article, the authors introduced new simultaneous, multiple-frequency, solitary-wave solutions to the traveling-wave parametric amplifier simultons, which exhibit phase-dependent collisions.
Abstract: We introduce new simultaneous, multiple-frequency, solitary-wave solutions to the traveling-wave parametric amplifier. Both degenerate and nondegenerate systems are treated including dispersion. These parametric amplifier simultons are shown to exhibit phase-dependent collisions. Spatial solitary waves are also found in the case of cw fields parametrically coupled in a planar waveguide.
111 citations
TL;DR: In this article, the authors used highly nondegenerate four-wave mixing in a semiconductor traveling-wave optical amplifier to achieve a power penalty of 1.1dB at 10/sup -9/ bit error rate (BER).
Abstract: Wavelength conversion of optical signals over 20 nm is demonstrated using highly nondegenerate four-wave mixing in a semiconductor traveling-wave optical amplifier. This technique has the potential for extremely-high-speed operation and allows continuous tuning of both input and output wavelengths over the amplifier gain bandwidth. It is demonstrated that, even for such a large wavelength conversion range, it is possible to obtain conversion efficiencies in excess of -10 dB and high extinction ratios. The feasibility of the technique is demonstrated by system measurements at 622 Mb/s, showing a 1.1-dB power penalty at 10/sup -9/ bit error rate (BER). >
109 citations
TL;DR: In this paper, the optical phase conjugation at the midpoint of a 100-km standard single-mode fiber was used to compensate for the distortion of 10-Gb/s intensity-modulated NRZ pulse at an input power level exceeding +10 dBm with a resultant power penalty of less than 1.2 dB.
Abstract: Pulse shape distortion due to chromatic dispersion and self-phase modulation in a single-mode fiber was effectively compensated for by using an optical phase-conjugate wave generated by nondegenerate forward four-wave mixing in a zero-dispersion single-mode fiber. Using optical phase conjugation at the midpoint of a 100-km standard single-mode fiber compensates for the distortion of 10-Gb/s intensity-modulated NRZ pulse at an input power level exceeding +10 dBm with a resultant power penalty of less than 1.2 dB. >
91 citations
TL;DR: In this article, a 1.5μm tensile-strained quantum-well optical amplifier has been studied by highly nondegenerate four-wave mixing at detuning frequencies up to 1.7 THz, and frequency response data indicate the presence of two ultrafast physical processes with characteristic relaxation lifetimes of 650 fs and <100 fs.
Abstract: Ultrafast dynamics in a 1.5‐μm tensile‐strained quantum‐well optical amplifier has been studied by highly nondegenerate four‐wave mixing at detuning frequencies up to 1.7 THz. Frequency response data indicate the presence of two ultrafast physical processes with characteristic relaxation lifetimes of 650 fs and <100 fs. The longer time constant is believed to be associated with the dynamic carrier heating effect. This is in agreement with previous time‐domain pump‐probe measurements using ultrashort optical pulses.
87 citations
TL;DR: In this article, the authors demonstrate a Kerr coefficient measurement of dispersion-shifted fibers based on the nonlinear mixing process between two continuous pump waves and on the power measurements of the created frequencies.
Abstract: We demonstrate a Kerr coefficient measurement of dispersion-shifted fibers based on the nonlinear mixing process between two continuous pump waves and on the power measurements of the created frequencies. A numerical model simulates the experimental conditions and is exploited to determine the Kerr coefficient. Unavoidable polarization effects are precisely taken into account both experimentally and numerically by launching the pump waves on the principal polarization states. This allows us to obtain reproducible measured values and a better than 5% resolution. >
83 citations
TL;DR: Beats between close-lying bound-exciton resonances in CdSe are found to be described by macroscopic polarization interferences between two noninteracting two-level systems, i.e., as a true quantum interference phenomenon.
Abstract: The nature of the beat modulations observed in nonlinear four-wave mixing in semiconductors is determined by spectral resolution of the time-integrated four-wave-mixing signals. Beats between close-lying bound-exciton resonances in CdSe are found to be described by macroscopic polarization interferences between two noninteracting two-level systems. Beats between heavy-hole excitons and light-hole excitons in GaAs quantum wells, on the other hand, are described by a three-level system, i.e., as a true quantum interference phenomenon.
80 citations
TL;DR: Wave mixing is demonstrated in dynamic gain gratings induced by counterpropagating beams from a diode laser in erbium-doped fiber amplifiers.
Abstract: We present a study of nonlinear wave mixing in erbium-doped fiber amplifiers. Wave mixing is demonstrated in dynamic gain gratings induced by counterpropagating beams from a diode laser.
75 citations
TL;DR: In this paper, the saturation effects in gas-phase degenerate four-wave mixing (DFWM) are investigated for conditions of interest for diagnostic applications in flames and plasmas.
Abstract: Saturation effects in gas-phase degenerate four-wave mixing (DFWM) are investigated for conditions of interest for diagnostic applications in flames and plasmas. In particular, the case in which Doppler and collisional broadening are comparable, as is often the case for flame species such as NO and OH, is investigated. DFWM line shapes and signal intensities are calculated nonperturbatively and compared with high-resolution laser measurements. In the nonperturbative calculations the time-dependent density-matrix equations for a two-level system interacting with three laser fields are integrated directly on a grid of spatial locations along the phase-matching axis. The electric-field amplitude for the DFWM signal is determined by multiplying the time-varying, laser-induced polarization at each grid point by the appropriate phase factor and then by summing over all grid points. The calculations are in excellent agreement with measurements of DFWM line shapes and signal intensities for NO in a buffer gas of He over a wide range of He pressure. Under saturation conditions the pressure dependence of the DFWM signal is reduced greatly compared with the unsaturated case. The signal level is still dependent on the ratio of pure dephasing to quenching collisions, even for saturation conditions. From the standpoint of minimal dependence on collisional processes it appears that operation with pump-laser intensities approximately equal to the saturation intensity is optimal. The dependence of the DFWM line shape and signal intensity on the ratio of probe to pump-laser intensity is also investigated.
64 citations
TL;DR: In this article, a multichannel frequency conversion using four-wave mixing is demonstrated using a polarisation independent configuration, by which polarisation control for each signal is not necessary.
Abstract: Multichannel frequency conversion is demonstrated using fourwave mixing. A polarisation independent configuration is employed, by which polarisation control for each signal is not necessary. By setting the pump light frequency at the zero-dispersion wavelength of the fibre, three FSK modulated signals with a frequency spacing of 70 GHz are simultaneously converted with an equal efficiency of −27.5dB. Bit error rate measurements confirm the feasibility of this conversion scheme.
62 citations
TL;DR: In this paper, a chromatic dispersion compensation technique employing phase conjugation was used to transmit a directly modulated 2.5 Gbit/s signal at 1.5 μm wavelength through 400km of normal-dispersion fibre.
Abstract: A chromatic dispersion compensation technique employing phase conjugation is used to transmit a directly-modulated 2.5 Gbit/s signal at 1.5 μm wavelength through 400km of normal-dispersion fibre.
TL;DR: It will be shown that the transient-grating-scattering type of experiment with chirped pulses provides an immediate answer to the question of whether the dynamics of a system occurs on a fast and/or slow time scale.
Abstract: We will demonstrate that four-wave mixing with linearly chirped (phase-modulated) pulses is a unique tool for obtaining information on the dynamics and level structure of,a system. Especially, it will be shown that the transient-grating-scattering type of experiment with chirped pulses provides an immediate answer to the question of whether the dynamics of a system occurs on a fast and/or slow time scale. In addition, we present compelling evidence that chirped four-wave mixing in a molecular system is a viable method for measuring excited-state vibrational frequencies. Double-sided Feynman diagrams are used for a third-order perturbative calculation of two-level four-wave-mixing effects and chirped coherent Raman scattering. The diagrams provide a visual representation of the quantum-mechanical pathways that the system can take as a result of the different field interactions. The number of quantum-mechanical pathways that contribute to the signal is shown to depend on the chirp rate compared to the time scale(s) of the system dynamics. A stochastic model is used to describe the optical dynamics of the system. The resulting expressions for the third-order nonlinear polarization are so complex that numerical calculations are necessary to simulate the time dependence of the optical response. It will also be shown that our theoretical results in the appropriate limits converge to those obtained for impulsive or continuous-wave excitation.
TL;DR: In this paper, the phase and amplitude characteristics of nearly degenerate four-wave mixing in a semiconductor laser are studied, and the experimental data can be quantitatively understood with a theoretical analysis in terms of the phase-and amplitude-modulations caused by mixing between the optical fields in the injected laser.
Abstract: The phase and amplitude characteristics of nearly degenerate four‐wave mixing in a semiconductor laser are studied. The experimental data can be quantitatively understood with a theoretical analysis in terms of the phase and amplitude modulations caused by mixing between the optical fields in the injected laser.
TL;DR: In this paper, a coupled mode formalism is proposed to solve the nonlinear differential equations in the mean field approximation for nearly degenerate four-wave mixing in distributed feedback semiconductor lasers above threshold in investigated theoretically and experimentally.
Abstract: Nearly degenerate four-wave mixing in distributed feedback semiconductor lasers above threshold in investigated theoretically and experimentally. The experimental results reveal an almost symmetric amplification of probe and conjugate fields versus frequency with respect to zero pump-probe detuning, in contrast with observations in traveling wave amplifiers. The result of the theory, based on the coupled mode formalism, is a set of nonlinear differential equations which are solved in the mean field approximation. The theory is shown to match well with the experimental results when the effect of the nonlinear gain compression is taken into account. >
TL;DR: In this article, the phase relationship of the FWM light components is randomized by combinations of optical multi-/demultiplexers and a delay line, so that the total FWM power power is reduced.
Abstract: A technique is proposed for suppressing four-wave mixing (FWM) in optical fiber lines that have multistage optical amplifiers. The phase relationship of the FWM light components is randomized by combinations of optical multi-/demultiplexers and a delay line, so that the total FWM light power is reduced. A preliminary experiment confirming the suppression mechanism is carried out, and the effect of the new suppression technique in multichannel systems is evaluated. The calculations show that the technique reduces the FWM crosstalk in the zero-dispersion wavelength region. >
TL;DR: The quantum beat and the polarisation interference phenomena observed as oscillations in pulsed four-wave mixing are analyzed theoretically and it is very simple to distinguish between polarised interference from two independent optical transitions and quantum beats from a three-level system.
Abstract: We analyze theoretically the quantum beat and the polarization interference phenomena observed as oscillations in pulsed four-wave mixing. We show that resolution of the signal with respect to the delay between the incoming pulses as well as the detection frequency provides valuable information on the nature of the oscillations. Most importantly, it is very simple to distinguish between polarization interference from two independent optical transitions and quantum beats from a three-level system. In case of polarization interference, the phase of the oscillations shifts \ensuremath{\pi} when the detected frequency passes any of the resonances. In case of quantum beat, the phase has little dependence on the detected frequency near the resonance.
TL;DR: In this paper, a theory of terahertz optical-frequency conversion using highly nondegenerate four-wave mixing (FWM) in an injection-locked semiconductor laser is presented, using small-signal analysis.
Abstract: A theory of terahertz optical-frequency conversion using highly nondegenerate four-wave mixing (FWM) in an injection-locked semiconductor laser is presented, using small-signal analysis. The optical frequency conversion can be realized through the use of cavity-enhanced highly nondegenerate FWM in an injection-locked semiconductor laser in a range of 1-THz detuning frequency between the pump and the probe waves, when the probe frequency is tuned close to one of the resonance modes. The frequency conversion is mainly attributed to the nonlinear gain effect. The maximum bandwidth of the converted signal is increased by shortening the laser cavity length. The frequency conversion efficiency is asymmetrical with respect to both the zero detuning frequency and the resonance mode where the converted signal appears. The theoretical results agree with experiments. >
TL;DR: Conical continuum Stokes and anti-Stokes emissions are observed when intense 100-fs/620-nm ultrafast laser pulses propagate through an ethylene glycol medium using class-II Raman and four-photon parametric generations in a small-scale filament with a nonlinear index change.
Abstract: Conical continuum Stokes and anti-Stokes emissions are observed when intense 100-fs/620-nm ultrafast laser pulses propagate through an ethylene glycol medium. The angle of the anti-Stokes conical emission is modeled by class-II Raman and four-photon parametric generations in a small-scale filament with a nonlinear index change.
TL;DR: Two-wave mixing at λ = 1.06 μm in the saturable gain of a flash-lamp-pumped Nd:YAG amplifier was investigated by development of a transient analysis and it is shown that energy redistribution can occur, thus leading to the depletion of a low-intensity signal beam.
Abstract: Two-wave mixing at λ = 1.06 μm in the saturable gain of a flash-lamp-pumped Nd:YAG amplifier was investigated, both experimentally and theoretically, by development of a transient analysis. Despite the local response of the inverted medium, it is shown that energy redistribution can occur, thus leading to the depletion of a low-intensity signal beam. Finally we measured a diffraction efficiency of 20% of the transmission-gain grating by diffracting a probe beam at λ = 1.06 μm under the Bragg condition.
TL;DR: In this paper, the HCO radical was detected by degenerate four wave mixing (D4WM) spectroscopy following 308 nm photolysis of CH3CHO, and the detection limit was estimated to be approximately 1 × 1012 cm−3 quantum state−1.
TL;DR: In this article, a new model is proposed to explain the origin of the self-pumped phase conjugation (SPPC) that we have observed in KTa1−xNbxO3:Fe crystals.
Abstract: A new model is proposed to explain the origin of the self‐pumped phase conjugation (SPPC) that we have observed in KTa1−xNbxO3:Fe crystals. In this model SPPC is generated by both four‐wave mixing and backscattering processes rather than by only one of them. The advantage of this kind of phase conjugator is also discussed.
TL;DR: Optical phase conjugation by "forward-scattering" degenerate four-wave mixing in an absorbing liquid analyte solution is reported as a sensitive and simple nonlinear laser spectroscopic method.
Abstract: Optical phase conjugation by "forward-scattering" degenerate four-wave mixing in an absorbing liquid analyte solution is reported as a sensitive and simple nonlinear laser spectroscopic method. Since only two input laser beams are used in this nonlinear four-wave mixing setup, it offers important advantages including ease of optical alignment, efficient use of input photon density, low laser power requirements, and high wave-mixing efficiency. In addition, since the phase-conjugate signal is a laser beam, optical signal detection is very efficient and the signal-to-noise is excellent. Important characteristics of this novel nonlinear laser technique, including signal dependence on analyte concentration, individual input beam power, and modulation frequencies, are examined. Excellent detection sensitivity, small detection volume, and convenient sample introduction promise many applications for this nonlinear laser spectroscopic method. Preliminary detection limits of 0.7 amol of eosin B and 45 amol of iodine inside a probe volume of 98 pL are reported using a forward-scattering degenerate four-wave mixing setup.
TL;DR: In this article, a 1.5 μm compressively strained multiquantum-well semiconductor traveling-wave optical amplifier at detuning frequencies up to 600 GHz was investigated, and the nonlinear gain coefficient was estimated to be 4.3×10−23 m3.
Abstract: Highly nondegenerate four‐wave mixing was investigated in a 1.5 μm compressively strained multi‐quantum‐well semiconductor traveling‐wave optical amplifier at detuning frequencies up to 600 GHz. A gain nonlinearity with a characteristic relaxation time of 650 fs was determined from the data, and the nonlinear gain coefficient was estimated to be 4.3×10−23 m3. Dynamic carrier heating is believed to be the major source of nonlinear gain in this device at the wavelengths investigated.
TL;DR: For near-resonant excitation with intense ultrashort optical pulses, it is shown that even in a homogeneously broadened system, there is no pure free decay of the polarization.
Abstract: We discuss the temporal evolution of transient four-wave-mixing signals in semiconductors. For near-resonant excitation with intense ultrashort optical pulses, we show that even in a homogeneously broadened system, there is no pure free decay of the polarization. The bulk of the signal always appears delayed and its magnitude is determined by Coulomb interactions
TL;DR: The observation of ultrafast modulation due to the interference between third- and fifth-order optical polarizations was observed in semiconductor doped glasses by controlling the relative phase of the optical fields which induce distinct wave-mixing processes.
Abstract: We report on time-delayed wave-mixing experiments which allowed, for the first time, the observation of ultrafast modulation due to the interference between third- and fifth-order optical polarizations. The new effect was observed in semiconductor doped glasses by controlling the relative phase of the optical fields which induce distinct wave-mixing processes. The experiments allowed us to measure the relative phase between the nonlinear susceptibilities χ (3) and χ (5) as well as their relative magnitude. In principle the interference effect may be observed in a large variety of materials and the exploitation of this phenomenon to develop a new technique for nonlinear spectroscopy is also discussed
TL;DR: In this article, a four-wave difference-frequency mixing scheme based on near resonant two-photon excitation of xenon with a femtosecond KrF excimer laser system is used to generate tunable short pulse radiation in the VUV and UV spectral range between 133 and 355 nm with output energies of several microjoules.
Abstract: A four-wave difference-frequency mixing scheme based on near resonant two-photon excitation of xenon with a femtosecond KrF excimer laser system is used to generate tunable short pulse radiation in the VUV and UV spectral range between 133 and 355 nm with output energies of several microjoules. Tunable nanosecond laser radiation in the range from 1905 nm to 185 nm is used. At excimer laser wavelengths of 193 nm (ArF), 308 nm (XeCl) and 350 nm (XeF), the process has been used to generate high power short pulse radiation by double-pass amplification in an additional excimer laser discharge. Output energies of 1.9, 3.0, and 2.8 mJ, respectively, have been obtained so far at pulse durations in the range of 1 ps. Nonlinear susceptibilities for the difference-frequency mixing process are calculated using a stationary susceptibility formalism and compared to experimental values. >
TL;DR: In this article, the experimental results of two-pulse transient four-wave mixing near the first heavy-hole quantum-well exciton were reported and the selection rules for these transitions were discussed and confirmed the treatment of the excitonic transition as a three-level system.
Abstract: We report the experimental results of two-pulse transient four-wave mixing near the first heavy-hole quantum-well exciton. Input pulses with similar polarizations (circular or linear) measure the exciton dephasing rate; opposite circular polarized pulses produce no four-wave mixing signal, while crossed linear polarized pulses generate a weaker signal with a faster dephasing rate. This signal is attributed to the biexcitonic transition, which was directly observed in a separate nondegenerate four-wave mixing experiment. The selection rules for these transitions are discussed and confirm the treatment of the excitonic transition as a three-level system.
21 Feb 1993
TL;DR: In this article, the effects of chromatic dispersion and nonlinearities accumulate during propagation, thus severely limiting the achievable performance, and the use of dispersion-shifted fiber permits higher bit rates but enhances the efficiency of four-wave-mixing (FWM) wave generation by reducing the phase mismatch that is naturally provided by the fiber dispersion.
Abstract: Very-high-capacity long-haul optical communication systems without intermediate optoelectronic conversions can be conceived by using erbium-doped-fiber amplifiers and wavelength-division multiplexing (WDM). The effects of chromatic dispersion and nonlinearities, however, accumulate during propagation, thus severely limiting the achievable performance. The use of dispersion-shifted fiber permits higher bit rates but enhances the efficiency of four-wave-mixing (FWM) wave generation by reducing the phase mismatch that is naturally provided by the fiber dispersion,1 thus causing FWM to become the dominant nonlinear effect.2
TL;DR: In this paper, four-wave mixing in erbium-doped fiber amplifiers is presented and studied, and the coupling is measured as a function of their relative detuning.
Abstract: Four-wave mixing in erbium-doped fibre amplifiers is presented and studied. Coupling in two cases is demonstrated: first, where one laser supplies all three input beams, and second, where two different lasers are used and the coupling is measured as a function of their relative detuning. This has potential uses in dynamic fibre-optic applications, such as filters and wavelength routing.
TL;DR: In this article, the nonlinear optical properties of CdSe quantum dots are investigated using self-saturation and degenerate four-wave mixing techniques, and the saturation of the room temperature absorption coefficient, for a wavelength in the vicinity of the first exciton peak, is measured.
Abstract: The nonlinear optical properties of CdSe quantum dots are investigated using self‐saturation and degenerate four‐wave mixing techniques. The saturation of the room temperature absorption coefficient, for a wavelength in the vicinity of the first exciton peak, is measured. The measured data can be predicted from a description of the quantum dot as a two level, homogeneously broadened, saturating system. The variation of the four‐wave mixing reflectivity with intensity and with wavelength is reported. All four‐wave mixing data are also consistent with the homogeneously‐broadened two‐level model.