Blue PPLN chips are designed for blue light generation at either 473 nm or 488 nm based on second harmonic generation (SHG). The generated blue light at 473 nm has important application in laser display, while the generated blue light at 488 nm can be used in bio-instrumentation. We provide 5 mol% MgO doped congruent PPLN chips in a form of both bulk and waveguide, which have features such as high optical damage threshold and high efficiency.