The article describes a demonstration of a broadband, high-speed lithium niobate on sapphire (LNOS) Mach-Zehnder electro-optic modulator for mid-infrared (MIR) applications, operating within the 3.95 to 4.5 µm wavelength range. This modulator shows outstanding performance with a 3 dB bandwidth above 20 GHz, an extinction ratio of 17 dB, and a voltage-length product (VπL) of 22 V·cm. The device operates with optical output power at the half-milliwatt level and successfully transmits 10 Gbit/s of data.
The article highlights that the mid-infrared spectrum, ranging from 3 to 14 µm, offers significant advantages for molecular spectroscopy and free-space optical communication. It discusses the challenges of achieving efficient electro-optic modulators in this range due to material and fabrication limitations, specifically addressing the need for low-loss, high-performance devices for phase and amplitude modulation in applications such as spectroscopy and high-speed data transmission.
The LNOS platform is introduced as a promising solution to extend the operational wavelength beyond 3.8 µm, addressing the limitations of traditional lithium niobate on insulator (LNOI) modulators. By replacing the SiO2 substrate with sapphire, the LNOS platform achieves low-loss, high-confinement waveguides suitable for MIR wavelengths, maintaining the electro-optic advantages of lithium niobate.
In terms of design, the modulator is based on a traveling-wave Mach-Zehnder interferometer architecture. The fabrication process incorporates advanced techniques such as electron-beam lithography and reactive ion etching, ensuring high precision. The device demonstrates a VπL product and bandwidth surpassing the current state of the art in MIR modulator technology, making it a valuable component for future applications in MIR photonics, coherent sensing, and high-resolution spectroscopy.
Additionally, the modulator's high-speed performance was characterized, showing an impressive 20 GHz bandwidth, with data transmission experiments conducted using a pseudo-random bit sequence at 10 Gbit/s. Furthermore, the modulator's performance was evaluated for frequency comb generation, achieving a 70 GHz bandwidth with distinct sidebands, making it an ideal candidate for MIR frequency comb generation and broad-spectrum spectroscopic systems.
This work paves the way for more efficient, integrated MIR modulators for advanced optical communication and sensing applications.
OMeda (Shanghai Omedasemi Co.,Ltd) was founded in 2021 by 3 doctors with more than 10 years of experience in nanpfabrication. It currently has 15 employees and has rich experience in nanofabrication (coating, lithography, etching, two-photon printing, bonding) and other processes. We support nanofabrication of 4/6/8-inch wafers.
