Highly-damage-resistant quasi-phase-matched wavelength converter using ZnO-doped LiNbO3

An all-optical wavelength converter is one of the key devices for realizing future high-speed and flexible wavelength-division multiplexed (WDM) networks. 1.55 μm-band quasi-phase-matched (QPM) wavelength converters based on difference frequency generation (DFG) in periodically poled LiNbO₃ (LN) are promising for this application because of their novel features, such as multi-channel conversion, high-efficiency, low noise, and transparency to bit-rate and data format. However, a QPM-LN wavelength converter using congruent LN exhibits photorefractive damage when it is injected with a high-power pump light. One approach to reducing photorefractive damage is to use MgO- or ZnO-doped LN. In this paper, we report a highly-damage-resistant QPM wavelength converter that uses a ZnO-doped LN substrate. The high damage resistance allows high-intensity pumping, which results in high conversion efficiency.