Low voltage visible light modulation for three colors (red, green, blue) by sputtered lithium niobate thin film

In this study, lithium niobate (LN) optical modulator devices were fabricated using cost-effective sputtered LN thin films. We successfully achieved a significantly small product of half-wave voltage and interaction electrode length (VπL) of 1.2, 1.0, and 0.75 V cm using red (λ = 638 nm), green (λ = 520 nm), and blue (λ = 473 nm) laser light, respectively. This small VπL is owing to the use of a low dielectric material of LaAlSiInOx for buffer insulator between LN waveguides and electrodes, and the change of geometrical configuration of the electrode. Thus, fabricating visible light modulators at low cost can be realized, and sputtered LN thin films can be adopted for visible light communications and consumer-based applications.