Application Cases

Name of experiment：Wafer-Scale Periodic Poling of Thin-Film Lithium Niobate

Research direction：nonlinear photonic integrated circuits (PICs)

Content of experiment：Composed of comb-like positive electrodes and flat negative electrodes, 70 nm thick Cr plus Au was patterned on the

600 nmthick x-cut LNOI wafer with photolithography. Being adaptable for mass production, the comb widths were varied with their corresponding

periods, and the pads were grouped by polarity within each block. By this means, the periodic domain structure in the whole wafer can be fabricated

by applying a consistent voltage waveform with as few operations as possible. High-quality poling was confirmed via characterization by confocal

second-harmonic microscopy , exhibiting 50% duty cycles, sufficient effective poling areas, thin domain walls, switching across the whole film thickness,

and overall uniformity along the z- and y-axes. As a result, reversal lengths span from 0.5 to 10.17 mm across the wafer and a maximum area of ~1 cm2

can be poled with a single manipulation with periods spanning from 4.38 to 5.51 µm, suitable for potential χ(2) applications in telecommunication bands.

Zooming out to the entire wafer, we obtained uniform and high-fidelity poling results with a 100% success rate and an average 98% high-quality rate

over all 21 blocks. This groundbreaking approach not only outperforms traditional chip-scale proofs of concept but also paves the way for the mass

manufacturing of PPLNOI devices, marking a significant leap toward industrial-scale production. Our method, ready for application in a multitude of

nonlinear processes for multifunctional complex PICs, represents a substantial advancement in the field, offering a scalable and efficient solution to the

challenges previously faced by researchers and manufacturers alike.

Test equipment：ATA-7020 High Voltage Amplifier, waveform generator,oscilloscope.

Experimental process：

The wafer with the electrode layer was connected to the circuit shown in Figure 1a by a pair of probes. In order to prevent air breakdown caused by high electric field strength, a thin layer of silicone oil was dropped onto the electrode surface before poling. The voltage amplifier (Aigtek ATA-7020) amplifies the preset pulse generated from the arbitrary waveform generator (AWG) (Rigol DG4062) as the input of the circuit. We monitored both the amplified pulse signal and poling current as feedback in real time with an oscilloscope (Tektronix TDS 2024C). A high-voltage resistor and a diode were connected in series in the loop to protect the circuit against high current and backflow.

Figure 1. (a) The schematic diagram of the circuit setup for electric field poling of LNOI. (b) A typical confocal microscope image with electrode and domain structures poled with a typical set of poling parameters. The arrows represent the spontaneous polarization Ps in each domain. The 2 µm 

scale bars are annotated.

Result of experiment：we have designed and exhibited high-quality periodic poling processing tailored for the wafer-scale PPLNOI platform. Leveraging the principles of ferroelectric domain switching, we have optimized the poling pulse shape and repetition times for high quality poling, ensuring 50% duty cycles with sufficient effective poling areas, thin domain walls, inversion across the whole film thickness, and overall uniformity along both the z- and y-axes. Comb line widths are meticulously adjusted to be compatible with the poling periods, and electrode pads within a 

block, corresponding to similar poling interval lengths,are strategically grouped to facilitate high-throughput and high-quality domain switching.

Through careful electrode design and parameters optimization, the reversal lengths span from 0.5 to 10.17 mm and a maximum ~1 cm2 area can be poled just in a single operation.The resulting uniform and high-quality poling performance, with a period range from 4.38 to 5.51 µm, demonstrates a 100% success rate and a 98% high-quality rate on average.

ATA-7020 High Voltage Amplifier

Bandwidth (-3dB)：DC~30kHz

Voltage：4kVp-p（±2kVp）

Current：30mAp

Power：60Wp

Slew rate：≥267V/μs