Nonlinear mode switching in lithium niobate nanowaveguides to control light directionality

Abstract

The ability of nanowaveguides to confine and guide light has been applied for developing optical applications such as nanolasers, optical switching and localized imaging. These and others applications can be further complemented by the optical control of the guided modes within the nanowaveguide, which in turn dictates the light emission pattern. It has been shown that the light directionality can be shaped by varying the nanowire cross-sections. Here, we demonstrate that the directionality of the light can be modified using a single nanowaveguide with a nonlinear phenomenon such as second-harmonic generation. In individual lithium niobate nanowaveguides, we use second-harmonic modal phase-matching and we apply it to switch the guided modes within its sub-micron cross-section. In doing so, we can vary the light directionality of the generated light from straight (0° with respect to the propagation direction) to large spread angles (almost 54°). Further, we characterize the directionality of the guided light by means of optical Fourier transformation and show that the directionality of the guided light changes for different wavelengths.

Enhanced Ultraviolet Damage Resistance in Magnesium Doped Lithium Niobate Crystals through Zirconium Co-Doping

“…The good news is that doping MgO into LiNbO 3 solves this problem well, and the optical damage resistance for LiNbO 3 can be increased by two orders of magnitude, substantially promoting its practical use in nonlinear optics [5,6]. Nowadays, MgO doped LN (LN:Mg) still garners extensive research interest in optical waveguide, domain engineering, and quasi-phase-matching, however, it should be noted that most of these researches have only been carried out in visible and infrared regions, but not in ultraviolet (UV) [7,8]. In fact, LN:Mg exposes the visible enhancement of UV photorefraction [9], and this is a serious problem that has become a noteworthy impediment to its extension of applications into UV regions.…”

Mapping of Fabry–Perot and whispering gallery modes in GaN microwires by nonlinear imaging

“…Far-field nonlinear optical microscopy is a fast noninvasive non-scanning technique that allows high-resolution mode imaging in nano-and microresonators [28,29]. Spatial information obtained from mode mapping is essential for the studies of local field distribution and enhancement [30,31] as well as diagnostics of devices in operation [32,33].…”