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Based on a two-energy-level system, we analyse the changing ground eigenenergies of symmetric GaAs/AlxGa1−x As coupled quantum wells in the presence of an applied electric field. From the theoretical analysis for symmetric coupled quantum well, we find the advantages and disadvantages when it is applied to travelling wave modulator. Hence the conception of quasi-symmetric coupled quantum wells is put forward. Based on the demands of travelling wave modulator for quantum well materials, the configuration of quasi-symmetric coupled quantum well is further optimized. Consequently, in the case of low applied electric field (F = 20 kV/cm) and low absorption loss (α≤100 cm−1), a large field-induced refractive change Δn (for TE mode, Δn = 0.021; for TM mode, Δn = 0.0121) is attained in the optimized coupled quantum well.

Low-loss glass-based buried multimode waveguides are fabricated by using the field-assisted Ag+-Na+ ion-exchange technique, and multimode optical power splitters are investigated. The measured loss of the multimode waveguides is lower than 0.1dB/cm, and the additional loss of the multimode optical power splitters is lower than 1.3 dB under the uniform splitting condition.