Investigation Of HNLF-based Multiple Four-Wave Mixing Effect And Applications

Four-wave mixing (FWM) is one of the most important nonlinearities in the optical fiber, by virtue of which, we can obtain new generated frequency components. Hence, it has a potential for the wide applications of optical communications systems, such as optical parametric amplification, transparent wavelength conversion, optical quantum information processing, optical time-division multiplexing (O-TDM), all-optical sampling, all-optical limiters and so on. In our thesis, we have carried out the investigation into the self-and cross-phase modulation (SPM and XPM), as well as the FWM in the highly nonlinear fiber (HNLF) theoretically and experimentally, and applied them to designing the novel filter,2R regenerator, ultra-wideband (UWB) generation and transmission, and so on. The most importantly, we discover a new characteristic in the HNLF called the "phase-clamping" effect, by which we realize the phase locking for the phase-incorrelation waves. The detailed research content is organized as follows:(1) We study the physical mechanism of MFWM-based coupled-wave equations. We start from the coupled-wave equations of the degenerate and non-degenerate FWM, and investigate their characteristics. In terms of this, we futher study the physical mechanism of MFWM-based coupled-wave equations. Second, we have derived the linear phase-matching profile under the condition of unequal detunes and multiple pumping sources.(2) We study the competition mechanism of the MFWM. By utilizing the coupled-wave equations, we analyze the competition mechanism of the MFWM, and confirm the relation between the mode quantity and the injected pumping strength by experiment, as well as summarizing the energy-flow rule among the waves in the MFWM process. Second, we discuss the stable property of Mode C in the MFWM system when the injected pump powers are equal or approximately equal. Through inducing the Hamiltonian and Manley-Rowe relation, we yield the phase-space trajectory describing the quantity of the energy-flow among the waves. By analyzing the topology structure of the phase-space orbit, the type and the existing condition of the singular point, we study the energy-flow quantity among the injected waves and sideband waves. Eventually, by investigating the potential and kinetic energy in the Hamilton system, we further study the stable characteristic of the Hamilton system.(3) We study the HNLF-based 2R regeneration effect. By using the coupled-wave equations, we study the static characteristic of the satellite wave, and derive the analytic expression describing the satellite wave evolving over the optical fiber. Second, we mimic the characteristic curve for describing the relation between the satellite-wave power and the injected-signal-wave power, which conforms to the transmission function curve of 2R regenerator, and by optimizing the injected wavelength and power, together with the optical fiber length, we can obtain the state-of-the-art transmission function curve. At last, we study the dynamic characteristic of the 2R regenerator, and successfully reshape and re-amplify the satellite, which not only suppresses the amplified spontaneous emission (ASE) noise at the space and mark of the satellite wave, but also improves the quality factor (Q) and the extinction ratio (ER).(4) We study the HNLF-based novel notch filter. With the aid of the coupled-wave equations, we obtain different optical spectra for the notch filter under the condition of different parameters, and improve its filtering capability by optimizing the related parameters. In reality, in order to eliminate the useless signal, we just decrease the detune of the pump and the signal waves, as well as judiciously tuning the pump power to meet the most optimized phase-matching condition.(5) We study the phase locking effect based on the HNLF. We first introduce the conception of the phase-clamping effect, which can be utilized to realize the phase locking for the two phase-incorrelation waves. We yield the analytic expression for the output wave phase from the coupled-wave equations, and confirm that the phase difference is constant as long as we neglect the FWM terms. Second, we extend the beating-frequency theory, and derive the autocorrelation trace and power spectral density function when N waves beat with each other. In experiment, we propose two schemes to confirm the availability of the phase locking when two or three phase-incorrelation waves interact with each other, respectively, and analyze the relation between the stable characteristic of the beat-note and the injected power or the polarization state.(6) We study the UWB generation based on the fiber optical parametric amplification (FOPA). By using the HNLF-based optical-parametric-attenuation effect and gain-oversatura-tion effect, we propose three schemes to generate the UWB signal. The first one is based on the single-pumped FOPA model, which realizes the single-channel UWB signal generation. The second one is based on the parallel structure of the single-pumped FOPA, comprising two pieces of HNLF, and it realizes six-channel polarity-inverted UWB signal generation. The third one is based on the dual-pumped FOPA model, and it realizes the dual-channel UWB signal generation.(7) We study the UWB-over-fiber technology. We introduce the arbitrary-waveform-decomposition (AWD) approach, by which we can yield the analytic expression from the nonlinear Schrodinger equation when the boundary condition is an arbitrary waveform pulse. This method not only simplifies the complex numerical algorithm, but also increases the speed of solving the equation and improves the accuracy of the solution. Moreover, this approach can be ulteriorly applied to optimizing the UWB waveform.