| Summary: | 碩士 === 國立中央大學 === 光電科學研究所 === 96 === A stable and efficient blue laser source has been one of the key elements used in biomedical, laser display, optical storage, and optical measurement systems. As an alternative to an attractive but not yet mature blue diode laser, in this work we try to develop a fabrication method of a quasi-phase-matching (QPM) second-harmonic generator in a low-loss optical-waveguide for achieving a high-efficiency blue laser based on a 5 mol. % MgO:LiNbO3 characterized by high optical nonlinearity and high optical damage resistance.
We have studied using a series of annealed proton exchanged (APE) channel waveguides of widths 3.5 μm, 4 μm, 4.5 μm, and 5 μm and a depth 4 μm to establish a fabrication model of a 976-nm frequency doubled MgO:PPLN APE waveguide. With this model, we can deduce the QPM grating period for this waveguided frequency doubling process via the calculation of the effective refractive indices of the fundamental and second-harmonic waves. We also fabricated a qualified low-loss APE waveguide with a measured waveguide loss of ~0.15 dB/cm. Besides, in this work we have successfully implemented a 3rd order QPM grating period of ~14.8 μm in a MgO:LiNbO3 crystal for the 976-nm waveguided frequency doubling process. We are possible to fabricate these MgO:PPLN with a QPM grating of 50% duty cycle.
We have also obtained some preliminary results on the study and fabrication of the soft proton exchanged (SPE) waveguides and 1st order QPM grating in a MgO:LiNbO3. We will discuss the improvement and practice schemes of these two advanced fabrication methods.
|
|---|
