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The nonlinear effects in optical resonators give a promise for the generation of new laser sources. Here, a whispering gallery mode(WGM) micro-rod resonator is fabricated and the mechanism of transmission between Kerr comb to Raman comb is investigated by experimental results and amended Lugiato-Lefever equation(LLE) model. We show that, numerically and experimentally, the WGM resonator-based optical frequency comb can be selectively accessed from Kerr comb state to Kerr-Raman state via pump and detuning controlling. When the detuning is initially set at red detuning, by simply increasing the pump power, the comb state can lock to the stable Raman soliton comb. This indicates the Raman soliton comb is easier to generate compared to the Kerr soliton comb in silica-based WGM resonator. We wish the experimental results demonstrated here can be used for broadband comb applications. [ABSTRACT FROM AUTHOR]

We investigated high-order harmonic generation in molecules N2 and C6H6 irradiated by bichromatic counter-rotating circularly polarized laser pulses by using time-dependent density-functional theory methods. It is found that $3N$ ($N$ is an integer) order harmonics in C6H6 disappear. Whereas, $N$ order harmonics are obtained in N2. Analysis of the high harmonic generated from individual electronic orbital of the molecule, shows that, the characteristics of harmonic spectra are determined by the spatial distribution of electronic orbits. Moreover, effects of molecular orientation on harmonic emission are also presented. [ABSTRACT FROM AUTHOR]

We proposed a new reservoir computation (RC) structure using polarization dynamics of vertical cavity surface emitting lasers (VCSELs) with optoelectronic feedback. Santa-Fe time-series prediction and nonlinear channel equalization were used to evaluate its parallel processing capability. We numerically discussed the effects of feedback strength, injection strength, frequency detuning, injection current and scaling factors on the RC performance of the system. The results show that, the operation range of negative feedback is larger than that of positive feedback; under appropriate feedback and lager injection strengths, good RC performance can be achieved for a wider injection current; with continuous variation of feedback strength from negative to positive values, the optimized location for frequency detuning moves from positive to negative values. We also evaluated the processing rate of proposed RC structure. The related study is helpful for the design and optimization of VCSEL-based RC under optoelectronic feedback. [ABSTRACT FROM AUTHOR]