Four-wave mixing

About: Four-wave mixing is a research topic. Over the lifetime, 7530 publications have been published within this topic receiving 112702 citations.

Width-tunable optical RZ pulse train generation based on four-wave mixing in highly nonlinear fiber

Abstract: We demonstrate a simple technique for width-tunable optical return-to-zero pulse train generation based on four-wave mixing in highly nonlinear fiber. By electrically tuning the delay between two pump pulse trains, the pulsewidth of a generated pulse train is continuously tuned. In our experiment, the full-width at half-maximum (FWHM) of a 5G pulse train is tuned from 85 to 25 ps, and the FWHM of a 10G pulse train is tuned from 33 to 18 ps. And the simulation results show that the FWHM of a 40G pulse train can be tuned continuously from 10.6 to 2.9 ps. Negligible power penalty is observed after 59-km single-mode fiber and 11.4-km dispersion-compensation-fiber transmission for different pulsewidths at 10 Gb/s.

Femtosecond continuum interferometer for transient phase and transmission spectroscopy

Abstract: We measure difference phase spectra (DPS) over the whole visible spectrum by frequency-domain interferometry (FDI), using chirped femtosecond continuum pulses. The effects of the probe-pulse chirp on time-resolved dispersion relations are studied. Because of the correspondence between time and frequency in the chirp, temporal evolution of the optical Kerr response in CS2 is projected into DPS. In addition, it is found that the chirped continuum shows unexpected frequency shifts owing to induced phase modulation even when the continuum has a flat spectrum. The chirp character can be readily obtained from the projected traces, and the potential application to the single-shot pulse-shape measurement by FDI is discussed. It is shown that the delay-time-corrected spectra satisfy the Kramers–Kronig relations if the continuum has a flat spectrum and does not have higher chirp than the linear chirp but that the distortion caused by the induced modulation of the continuum remains unremoved in the corrected spectra.

Determination of the electric field strength of filamentary DBDs by CARS-based four-wave mixing

Abstract: It is demonstrated that a four-wave mixing technique based on coherent anti-Stokes Raman spectroscopy (CARS) can determine the electric field strength of a pulsed-driven filamentary dielectric barrier discharge (DBD) of 1 mm gap, using hydrogen as a tracer medium in nitrogen at atmospheric pressure. The measurements are presented for a hydrogen admixture of 10%, but even 5% H2 admixture delivers sufficient infrared signals. The lasers do not affect the discharge by photoionization or by other radiation-induced processes. The absolute values of the electric field strength can be determined by the calibration of the CARS setup with high voltage amplitudes below the ignition threshold of the arrangement. This procedure also enables the determination of the applied breakdown voltage. The alteration of the electric field is observed during the internal polarity reversal and the breakdown process. One advantage of the CARS technique over emission-based methods is that it can be used independently of emission, e.g. in the pre-phase and in between two consecutive discharges, where no emission occurs at all.

Measuring absorptive two-dimensional infrared spectra using chirped-pulse upconversion detection

Abstract: Chirped-pulse upconversion (CPU) enables the detection of mid-infrared spectra using a silicon CCD camera by sum-frequency mixing a mid-IR field with a highly chirped near-IR (800 nm) field. Although the substantial chirp limits the spectral broadening and phase distortions caused by the inherent cross-phase modulation, the exquisite phase fidelity needed to measure a fully absorptive two-dimensional IR spectrum demands the correction of the phase distortions. We demonstrate how to correct all of the phase distortions involved in recording an absorptive 2DIR spectrum including delay stage calibrations as well as the requisite nonlinear signals. Besides the extra experimental step of the upconversion process itself, the phase correction procedure requires only the knowledge of the spectral or temporal phase of the chirped pulse. The method is demonstrated in a metal carbonyl complex, Mn2(CO)10, in n-hexane and methanol solvents showing that the method operates well in cases of both homogeneous and inhomogeneous broadening.

Coherent coupling of multiple transverse modes in a quantum cascade laser

Abstract: We investigate phase coherence of multi-transverse modes in quantum cascade lasers through both near- and far-field mode measurements. We explain the observed phase locking by four-wave mixing of longitudinal modes belonging to different transverse modes.