Spatial homogeneity of optically switched semiconductor photonic crystals and of bulk semiconductors

Tijmen G. Euser, Willem L. Vos

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56 Citations (Scopus)
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In this paper we discuss free carrier generation by pulsed laser fields as a mechanism to switch the optical properties of semiconductor photonic crystals and bulk semiconductors on an ultrafast time scale. Requirements are set for the switching magnitude, the time-scale, the induced absorption, as well as the spatial homogeneity, in particular for silicon at λ=1550nm. Using a nonlinear absorption model, we calculate carrier depth profiles and define a homogeneity length lhom. Homogeneity length contours are visualized in a plane spanned by the linear and two-photon absorption coefficients. Such a generalized homogeneity plot allows us to find optimum switching conditions at pump frequencies near ν/c=5000cm−1 (λ=2000nm). We discuss the effect of scattering in photonic crystals on the homogeneity. We experimentally demonstrate a 10% refractive index switch in bulk silicon within 230fs with a lateral homogeneity of more than 30μm. Our results are relevant for switching of modulators in the absence of photonic crystals.
Original languageEnglish
Article number43102
Number of pages7
JournalJournal of Applied Physics
Issue number4
Publication statusPublished - 2005


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