Periodic Poling of Lithium Niobate Thin Films for Integrated Nonlinear Optics
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The Ohio State University / OhioLINK
2020
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ndltd-OhioLink-oai-etd.ohiolink.edu-osu15876731566658612021-08-03T07:14:39Z Periodic Poling of Lithium Niobate Thin Films for Integrated Nonlinear Optics Nagy, Jonathan Tyler Electrical Engineering Optics Electromagnetics integrated optics nonlinear optics photonic integrated circuits lithium niobate LNOI ferroelectric periodic poling domain engineering quasi-phase matching second harmonic generation crystal ion-slicing waveguide Single-crystal lithium niobate (LN) thin films have emerged as a promising platform for photonic integrated circuits with applications including quantum optics, spectroscopy, and high-speed communications. The LN films are well-suited for nonlinear optics owing to the high optical confinement compared to their bulk counterparts and their ferroelectric nature which enables quasi-phase matching by period poling. Poling of LN thin films presents new challenges due to large leakage currents and the relatively small domain size required for phase matching. Moreover, current poling techniques have not been able to reach submicrometer-scale poling periods suitable for first-order quasi-phase matched interactions with counter-propagating waves. In this dissertation, we fabricate lithium niobate thin films and demonstrate improved periodic poling techniques to enable efficient nonlinear photonic integrated circuits. Wafer-scale single-crystal LN thin films are produced by ion-slicing. The LN films are less than one micrometer thick and are bonded to a supporting oxidized LN wafer without the use any intermediate materials or adhesives. The films are chemically-mechanically polished to achieve a surface roughness less than 0.5 nm RMS. Large area void-free films are reliably produced with this process. In addition, fabrication processes to form silicon nitride strip-loaded waveguides and poling electrodes are developed based on electron beam lithography and plasma etching.A method of reducing the leakage current during electric field poling of x-cut magnesium oxide doped lithium niobate thin films is developed. The leakage current is reduced by introducing a silicon dioxide insulation layer under the co-planar electrodes. Uniform domains with a 7.5 μm period and 50% duty cycle are achieved. The poling characteristics are compared to bulk lithium niobate, with and without the silicon dioxide insulation layer. The domains are characterized on the surface by piezoresponse force microscopy and through the depth of the film by focused ion beam milling and selective hydrofluoric acid etching. In addition, second harmonic generation in a silicon nitride strip-loaded waveguide at a pump wavelength of 1550 nm is demonstrated and helps to confirm uniform poling. Poling is also performed in situ during the optical measurements and is investigated as a mechanism to switch the second harmonic signal on and off. The dependence of the second harmonic extinction ratio on the poling waveform voltage, duration, and time between pulses is characterized.We then develop a poling waveform to produce submicrometer-scale periods in x-cut LN thin films. Multiple bipolar preconditioning pulses are used to repeatedly pole and unpole the device prior to applying a single unipolar pulse. The preconditioning pulses improve the poling yield and domain uniformity. Also, the internal field is found to decrease with each preconditioning poling cycle and is reminiscent of the training effect observed in ferromagnetic materials. A period of 750 nm is achieved. 2020-09-02 English text The Ohio State University / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=osu1587673156665861 http://rave.ohiolink.edu/etdc/view?acc_num=osu1587673156665861 restricted--full text unavailable until 2025-05-13 This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws. |
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NDLTD |
| language |
English |
| sources |
NDLTD |
| topic |
Electrical Engineering Optics Electromagnetics integrated optics nonlinear optics photonic integrated circuits lithium niobate LNOI ferroelectric periodic poling domain engineering quasi-phase matching second harmonic generation crystal ion-slicing waveguide |
| spellingShingle |
Electrical Engineering Optics Electromagnetics integrated optics nonlinear optics photonic integrated circuits lithium niobate LNOI ferroelectric periodic poling domain engineering quasi-phase matching second harmonic generation crystal ion-slicing waveguide Nagy, Jonathan Tyler Periodic Poling of Lithium Niobate Thin Films for Integrated Nonlinear Optics |
| author |
Nagy, Jonathan Tyler |
| author_facet |
Nagy, Jonathan Tyler |
| author_sort |
Nagy, Jonathan Tyler |
| title |
Periodic Poling of Lithium Niobate Thin Films for Integrated Nonlinear Optics |
| title_short |
Periodic Poling of Lithium Niobate Thin Films for Integrated Nonlinear Optics |
| title_full |
Periodic Poling of Lithium Niobate Thin Films for Integrated Nonlinear Optics |
| title_fullStr |
Periodic Poling of Lithium Niobate Thin Films for Integrated Nonlinear Optics |
| title_full_unstemmed |
Periodic Poling of Lithium Niobate Thin Films for Integrated Nonlinear Optics |
| title_sort |
periodic poling of lithium niobate thin films for integrated nonlinear optics |
| publisher |
The Ohio State University / OhioLINK |
| publishDate |
2020 |
| url |
http://rave.ohiolink.edu/etdc/view?acc_num=osu1587673156665861 |
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AT nagyjonathantyler periodicpolingoflithiumniobatethinfilmsforintegratednonlinearoptics |
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