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Abstract

An intersubband (ISB) optical device comprises first quantum well (QW) interior regions having upper and lower energy states between which ISB transitions take place; and superlattice (SL) barrier regions interposed between the first QW interior regions. The SL barrier regions include second barriers and second QW interior regions, with the second QW interior regions being interposed between the second barrier regions. The first QW interior regions and the SL barrier regions are configured to produce an energy gap between the upper and lower states that is larger than the energy of a 1.7 .mu.m wavelength photon. In accordance with another aspect of our invention, an intersubband optical device comprises a core region that includes a multiplicity of repeat units (RUs), each RU including a first barrier region and a QW active region disposed adjacent thereto, characterized in that (1) each of the QWs has upper and lower energy states separated by an energy greater than that of a 1.7 .mu.m wavelength photon, (2) each of the first barrier regions comprises a SL, and (3) each SL is configured to have minibands and minigaps that provide for confinement of electrons in the upper state of the active QW. In a preferred embodiment, the SL first barrier region comprises second QW regions interleaved with second barrier regions, and the SL barrier region is doped only in the second QW regions, which are configured so that electrons therein tunnel into the first QW regions. In another embodiment, the device is formed on a lattice-mismatched substrate and a transition zone, that includes a strain-altering buffer region and a dislocation-reducing template region, is disposed between the substrate and the core region. One effect of the transition zone is to redistribute charge accumulated at the interfaces between the QW active regions and the first barrier regions.

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First Claim