Design of High-Speed Mid-Infrared Electro-Optic Modulator Based on Thin Film Lithium Niobate

It is particularly important to improve the performance of mid-infrared (mid-IR) electro-optic (EO) modulator, which is one of the key devices that will expand the channels of optic communication, and will be utilized in optical free space communication, optical detection for gas molecules, etc. We present and theoretically design the performance of the high-speed mid-IR EO modulator based on lithium niobate on insulator (LNOI) at lambda = 3 mu m. We have designed, calculated, and optimized single-mode ridge waveguide, 1 x 2 multimode interference (MMI) couplers and coplanar waveguide (CPW) electrodes structures for x-cut lithium niobate. Our device with an extinction ratio greater than 40 dB, a half-wave voltage-length product is about 12 V center dot cm, and a EO bandwidth up to 12 GHz with interaction length of 15 mm. The performance of interaction length of 5 mm and 10 mm mid-IR EO modulator are also proposed and simulated for a compromise consideration between the EO bandwidth and driving voltage.

Automated summary

Improving the performance of mid-infrared (mid-IR) electro-optic (EO) modulators is crucial for applications in optical communication and gas molecular detection. This study presents the theoretical design and performance analysis of a high-speed mid-IR EO modulator based on lithium niobate on insulator (LNOI) at a wavelength of 3 μm. The designed device features key components such as single-mode ridge waveguides, 1x2 multimode interference (MMI) couplers, and coplanar waveguide (CPW) electrodes, achieving an extinction ratio greater than 40 dB, a half-wave voltage-length product of approximately 12 V·cm, and an EO bandwidth of up to 12 GHz.