| 摘要 |
A laser oscillator to further shorten a pulse width is provided by enabling broadband mode-locking even while using a laser medium having a precipitous fluorescence peak. A resonator has two concave mirrors and four chirped mirrors, and cavity-dispersion is compensated by these chirped mirrors. A semiconductor laser output is focused through a first concave mirror onto the laser medium to produce a gain medium in the resonator, whereby a laser oscillation is realized. While setting a target value in layer thickness design of dielectric multilayer of the chirped mirrors so as to slightly lower reflectivity at a fluorescence peak wavelength of the laser medium, fitting is redone, whereby reflectivity is slightly changed without greatly changing group-delay dispersion. In this procedure, reflectivity is reduced in any one or some of the chirped mirrors to average the gain.
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