ピコ秒パルスレ-ザ-による超高速現象の測定-3-半導体(Si)の非線形吸収

概要

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The nonlinear optical absorption was observed in silicon at 200°K and largcly at 300°K with a Q-switched Nd3十glasslaser pulses of 300ns duration and a Y AG lascr of 15ns， although not at 77°K. The transmission as a function of the incidcnt. lascr intensity was also measured with picosccond pulses of mode-locked glass lasers. 1n this case， the nonlincar absorption was scarcely found even at 300°K. However、theabsorption saturation was observed， while the refiection decrcased， corresponding to thc clcctron-hole plasma created along the path of the incident beam beyond the photon number of 5x1013/㎠pulse. Therefore， it may be considered that the nonlinear absorption comes from the stepwise absorption of the photo-excited electrons in the conduction band rather than the direct two-photon processes.
福井大学工学部の論文