We present in this paper the fabrication and characterization of thermally stable double line waveguides in Z-cut periodically poled Lithium Niobate crystals. The waveguides were fabricated by using a femto-second laser, and utilized for second-harmonic generation. Our experiments have shown that a quasi-phase matching wavelength of 1548.2 nm, a tuning bandwidth of 2 nm, and a tuning temperature range of 150.4±1.6°C can be achieved.
Raman spectra of In0.65Al0.35As quantum dots (QDs) embedded between GaAlAs and GaP have been measured at room temperature. For the as-grown sample, in addition to the TO/LO modes from GaAs substrate, a weak broad peak appears from 165 cm-1 to 203 cm-1, corresponding to the interface mode of InAlAs QDs. The AlAs-like and GaP-like modes can be clearly seen at 382 cm-1. For the annealed samples, the AlAs and GaP-like modes disappeared, while the InAs-like modes become stronger, indicating strong intermixing between QDs and the matrix and the formation of uniform InGaAlAsP alloy.