| 摘要 |
Optical modulators include active quantum well structures coherent with pseudosubstrates comprising relaxed buffer layers on a silicon substrate. In a preferred method the active structures, consisting of Si1−x Gex barrier and well layers with different Ge contents x, are chosen in order to be strain compensated. The Ge content in the active structures may vary in a step-wise fashion along the growth direction or in the form of parabolas within the quantum well regions. Optical modulation may be achieved by a plurality of physical effects, such as the Quantum Confined or Optical Stark Effect, the Franz-Keldysh Effect, exciton quenching by hole injection, phase space filling, or temperature modulation. In a preferred method the modulator structures are grown epitaxially by low-energy plasma-enhanced chemical vapor deposition (LEPCVD).
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