Microstructure and domain engineering of lithium niobate crystal films for integrated photonic applications

Recently,integrated photonics has attracted considerable interest owing to its wide application in optical communication and quantum technologies.Among the numerous photonic materials,lithium niobate film on insulator(LNOI)has become a promising photonic platform owing to its electro-optic and nonlinear optical properties along with ultralow-loss and high-confinement nanophotonic lithium niobate waveguides fabricated by the complementary metal-oxide-semiconductor(CMOS)-compatible microstructure engineering of LNOI.Furthermore,ferroelectric domain engineering in combination with nanophotonic waveguides on LNOI is gradually accelerating the development of integrated nonlinear photonics,which will play an important role in quantum technologies because of its ability to be integrated with the generation,processing,and auxiliary detection of the quantum states of light.Herein,we review the recent progress in CMOS-compatible microstructure engineering and domain engineering of LNOI for integrated lithium niobate photonics involving photonic modulation and nonlinear photonics.We believe that the great progress in integrated photonics on LNOI will lead to a new generation of techniques.Thus,there remains an urgent need for efficient methods for the preparation of LNOI that are suitable for large-scale and low-cost manufacturing of integrated photonic devices and systems.

A 0.19 ppm/°C bandgap reference circuit with high-PSRR

A high-order curvature-compensated CMOS bandgap reference（BGR） topology with a low temperature coefficient（TC） over a wide temperature range and a high power supply reject ratio（PSRR） is presented.High-order correction is realized by incorporating a nonlinear current INL, which is generated by ？V_（GS） across resistor into current generated by a conventional first-order current-mode BGR circuit. In order to achieve a high PSRR over a broad frequency range, a voltage pre-regulating technique is applied. The circuit was implemented in CSMC 0.5 μm 600 V BCD process. The experimental results indicate that the proposed topology achieves TC of0.19 ppm/°C over the temperature range of 165 °C（-40 to 125 °C）, PSRR of-123 d B @ DC and-56 d B @ 100 k Hz. In addition, it achieves a line regulation performance of 0.017%/V in the supply range of 2.8–20 V.

Laser-processed lithium niobate wafer for pyroelectric sensor

During the past few decades, pyroelectric sensors have attracted extensiveattention due to their prominent features. However, their effectiveness is hinderedby low electric output. In this study, the laser processed lithium niobate(LPLN) wafers are fabricated to improve the temperature–voltage response.These processed wafers are utilized to construct pyroelectric sensors as well ashuman–machine interfaces. The laser induces escape of oxygen and the formationof oxygen vacancies, which enhance the charge transport capability on thesurface of lithium niobate (LN). Therefore, the electrodes gather an increasedquantity of charges, increasing the pyroelectric voltage on the LPLN wafers toa 1.3 times higher voltage than that of LN wafers. For the human–machineinterfaces, tactile information in various modes can be recognized by a sensorarray and the temperature warning system operates well. Therefore, the lasermodification approach is promising to enhance the performance of pyroelectricdevices for applications in human–machine interfaces.