Project TitleThin Film Waveguide Modulator with an Increased Electro-Optic Coefficient and Wider Bandwidth
Track Code2004-060
Short Description

A low-voltage, wide bandwidth, strip-loaded BaTiO3 thin film electrooptic amplitude modulator for use in high-speed optical communication networks. #photonics #wireless #optoelectronic #materials #thinfilm


Northwestern researchers have developed a low-voltage, wide bandwidth, strip-loaded Barium Titanate (BaTiO3) thin film electro-optic (EO) amplitude modulator for use in high-speed optical communication networks. They have demonstrated broadband modulation out to 40 GHz, at which value low power EO waveguide modulators may have high EO coefficients. EO waveguide modulators are essential for high speed and wide bandwidth optical communication systems. Currently, Lithium Niobate is widely used for low loss, low drive voltage, and high-speed modulators due to its high EO coefficient and excellent optical transparency. However, BaTiO3 has an EO coefficient that is forty times greater and promises improved performance while employing smaller devices. Nevertheless, the large bulk dielectric constant of BaTiO3 limits its high modulation bandwidth operation. To address this limitation, BaTiO3 can be combined with MgO as a composite, which lowers the effective microwave index and improves velocity matching between the microwave and optical waves. Furthermore, BaTiO3 can be integrated with silicon substrates using a thin film MgO buffer layer, allowing integration on a single multicomponent chip with reduced packaging costs.

TagsPHOTONICS: nonlinear optics, COMMUNICATIONS: wireless, DEVICES: optoelectronic, MATERIALS: thin film
Posted DateMay 3, 2011 1:51 PM


Anthony Meier
Pingsheng Tang
David Towner
Bruce Wessels*


  • High-speed optical communication networks


  • Compatible with silicon substrates
  • Significantly increased EO coefficient
  • Decreased effective microwave index
  • Improved velocity matching between microwave and optical waves
  • Wide bandwidth over 40 GHz

IP Status

Issued U.S. Patent No. 7,224,878

Contact Information

Arjan Quist, PhD

Invention Manager

(p) 847-467-0305