Periodically poled crystals are key components of many nonlinear-optical frequency converters, ranging from the visible spectral range up to the THz range. Fraunhofer IPM has developed a maskless poling technique combining short turnaround times, full flexibility in poling-pattern design with high quality poling results in materials like LiNbO3, LiTaO3 and BaMgF4.

The working principle

Maskless domain inversion is achieved by moving a metal tip over the surface of an unpoled lithium niobate crystal. A high voltage between the tip and a planar metallic bottom electrode leads to a well localized μm-sized domain inversion, right below the tip. By displacing the charged tip with high precision, we can serially write domain lines into the crystal. To ensure high-quality poling results, the electrical poling current is monitored and controlled.

The technique delivers high-quality poling results independent of the crystal’s crystallographic x- and y-axes. Thus, any structure (e.g. fan-out, or radial patterns) can be written. The quality of the poling pattern can be checked via bi-sided domain selective etching.

Your benefit

Fraunhofer IPM offers maskless poling as a service, ranging from one-of-a-kind to small-volume production. You will benefit from short turnaround times, which gives you a temporal advance for your research or product development. If requested, dicing and polishing can be offered as well. Besides »poling-as-a-service«, Fraunhofer IPM offers turn-key poling machines for your own in-house maskless poling production, without the need for clean-room facilities.