Ultrafast spectroscopy of semiconductor saturable absorber mirror （SESAM） is measured using a femtosec- ond pump-probe experiment. This allows dynamic responses of SESAM in the cavity to be concluded by ultrafast sp...Ultrafast spectroscopy of semiconductor saturable absorber mirror （SESAM） is measured using a femtosec- ond pump-probe experiment. This allows dynamic responses of SESAM in the cavity to be concluded by ultrafast spectroscopy. Change in reflection is measured as a function of pump-probe delay for different pump excitation fluences. Change of nonlinear reflection of SESAM is measured as a function of incident light energy density. When the excitation fluence increases, nonlinear change in ultrafast spectroscopy of SESAM becomes increasingly significant. When SESAM is pumped by an ultrahigh excitation fluence, the energy density of which is approximately 1400 μJ/cm2, two-photon absorption can be observed visibly in its ultrafast spectroscopy.展开更多
With the development of high power ultrafast laser passively mode-locked by a semiconductor saturable absorber mirror （SESAM）, the damage threshold and degeneration mechanism of the SESAM become more and more import...With the development of high power ultrafast laser passively mode-locked by a semiconductor saturable absorber mirror （SESAM）, the damage threshold and degeneration mechanism of the SESAM become more and more important. One way to reduce the maximum electric field inside the active part of the SESAM is the use of a dielectric coating on the top of the semiconductor structure. With Presnel formula, optical transfer matrix, and optical thin film theory, the electric field distribution and reflectance spectrum can be simulated. We introduce the design principles of SESAM including the dependence of reflectance spectrum on dielectric function of absorber, and investigate the dependences of the electric field distribution, modulation depth, reflectance spectrum, and the relative value of incident light power at the top quantum well of SESAM on the number of SiO2/Ta2O5 layers.展开更多
基金supported by the Ministry of Science,Research,and the Arts of Baden-Wrttemberg State of Germany and the Chinese Scholarship Council
文摘Ultrafast spectroscopy of semiconductor saturable absorber mirror （SESAM） is measured using a femtosec- ond pump-probe experiment. This allows dynamic responses of SESAM in the cavity to be concluded by ultrafast spectroscopy. Change in reflection is measured as a function of pump-probe delay for different pump excitation fluences. Change of nonlinear reflection of SESAM is measured as a function of incident light energy density. When the excitation fluence increases, nonlinear change in ultrafast spectroscopy of SESAM becomes increasingly significant. When SESAM is pumped by an ultrahigh excitation fluence, the energy density of which is approximately 1400 μJ/cm2, two-photon absorption can be observed visibly in its ultrafast spectroscopy.
基金supported by the Ministry of Science,Research and Arts of Baden-Württemberg State of Germany and the Chinese Scholarship Council.
文摘With the development of high power ultrafast laser passively mode-locked by a semiconductor saturable absorber mirror （SESAM）, the damage threshold and degeneration mechanism of the SESAM become more and more important. One way to reduce the maximum electric field inside the active part of the SESAM is the use of a dielectric coating on the top of the semiconductor structure. With Presnel formula, optical transfer matrix, and optical thin film theory, the electric field distribution and reflectance spectrum can be simulated. We introduce the design principles of SESAM including the dependence of reflectance spectrum on dielectric function of absorber, and investigate the dependences of the electric field distribution, modulation depth, reflectance spectrum, and the relative value of incident light power at the top quantum well of SESAM on the number of SiO2/Ta2O5 layers.
