Lithium niobate thick film-based high-speed electro-optical modulator and preparation method thereof

Abstract

The invention relates to the field of integrated optics, in particular to a lithium niobate thick film-based high-speed electro-optical modulator and a preparation method thereof; the modulator comprises a supporting substrate, a bonding layer, an optical waveguide and a modulation electrode, wherein the optical waveguide is located on the surface of the bonding layer, and a layer of lithium niobate thick film is arranged on the bonding layer; the thickness of the lithium niobate thick film is 8-20 microns; by virtue of about 10 microns of the ridge height of the thick-film lithium niobate, the modulation efficiency can be improved by 60% or above, and the substrate is only 8-20 microns in thickness due to the thinning technology, so that the resonance effect can be avoided, and the high-speed broadband can be further realized; and compared with a thin film type waveform lithium niobate modulator, the lithium niobate thick film-based high-speed electro-optical modulator has the advantages of being low in diffusion type optical waveguide transmission loss and low in coupling loss.

Description

technical field [0001] The invention relates to the field of integrated optics, in particular to a high-speed electro-optic modulator based on lithium niobate thick film and a preparation method thereof. Background technique [0002] The typical structure of a lithium niobate intensity modulator chip (taking an X-cut Y-passed lithium niobate chip as an example) is as follows: figure 1 As shown, the electric field distribution is as figure 2 shown. [0003] In order to reduce the half-wave voltage and achieve high-speed broadband. Researchers first used wet or dry etching to form a ridge-shaped lithium niobate optical waveguide structure to increase the overlap integral Γ of the electric field and the optical field. The height of the waveguide ridge is generally not more than 3 microns, and the etching process will also cause the side wall of the ridge optical waveguide to be rough, which will greatly increase the transmission loss of light. Therefore, the researchers com...

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Problems solved by technology

However, it is precisely because the mode field size of the ridge waveguide is less than 1 micron, while the mode field diameter of the optical fiber is usually about 9 microns, the difference between the two is nearly an order of magnitude, which leads to a substantial increase in the coupling loss between the optical fiber and the waveguide. Good coupling efficiency can only achieve a coupling loss of 5dB / end face, which is much higher than the coupling loss of 0.7-0.8dB / end face of the current commercial modulator, so this technology is currently difficult to achieve commercial use

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