How micro-heaters can be used to specifically improve the efficiency and spectral characteristics of non-linear processes.
Nonlinear frequency conversion, such as second harmonic generation, is widely used in various areas of photonics. Conversion based on χ(2)-nonlinear optical interactions can be very efficient in waveguide structures. In practice, however, the ideal properties are limited due to inhomogeneities along the interaction range, which always occur during the fabrication of such devices. In this publication, a post-trimming method is shown how these shortcomings can be overcome. As an example, the authors investigate devices for second harmonic generation in Ti-indiffused waveguides in periodically poled lithium niobate. With the help of micro-heaters, which are deposited directly on top of the waveguide chip, a temperature profile can be set in a targeted manner that exactly compensates for the inhomogeneity profile. This results in a significant increase in conversion efficiency on the one hand and the possibility of changing the spectral characteristics of the conversion on the other.
The publication "Tailored second harmonic generation in Ti-diffused PPLN waveguides using micro-heaters" by the authors J. Babai-Hemati, F. vom Bruch, H. Herrmann and C. Silberhorn has been published in the journal "Optics Express" (https://doi.org/10.1364/OE.510319).
