Fourier transformation using an electroabsorptive CCD spatial light modulator

Use of the Franz–Keldysh effect in self-biased p-i-n-heterostructures for saturable absorber mirrors

“…Figures 2 and 3 plot the screening potential ϕ, the absorption coefficient α, and the reflectance R = 1 − X for a bulk, undoped absorbing layer at two wavelengths, and also for an ESQW undoped absorbing layer. The material parameters in all cases have been taken from the literature [9,18]. Curves calculated for non-resonator case (R T = 0), as in [7] for a ESQW-SESAM, are plotted alongside those calculated when the SESAM has a resonant cavity with an uncoated top facet (R t = 0.3).…”

“…The phenomenological parameters α 0 (absorption coefficient at zero field), E 0 (characteristic field), and a of course depend on the photon energy deficit (E g − hω) > 0 with respect to the bandgap of a bulk or ESQW absorbing layer. In both cases, we follow [7] in using values extracted from the experiment (namely a = 0.09 V −1 , E 0 = 7.2 × 10 4 V cm −1 , α 0 = 100 cm −1 at λ = 0.873 μm [9] for the case of AlGaAs/GaAs ESQWs as in [7], and a = 0.018 V −1 , E 0 = 4 × 10 4 V cm −1 , α 0 = 100 cm −1 at λ = 0.89 μm (E g − hω = 0.031 eV), or a = 0.01 V −1 , E 0 = 9.2 × 10 4 V cm −1 , α 0 = 15 cm −1 at λ = 0.905 μm (E g − hω = 0.054 eV) [18] for the case of bulk GaAs). We note that the functional dependences of the parameters E 0 and a on (E g − hω) are consistent with the microscopic theory of the Franz-Keldysh effect [19], at least for bulk GaAs.…”