NU 2008-009

Inventors

Bruce Wessels*

Pao Tai Lin

Short Description

Highly efficient broadband SHG in the visible spectrum promising broad band sources for potential integrated photonic circuits.

Abstract

Northwestern researchers have developed highly efficient broadband second harmonic generation (SHG) in the visible spectrum, which promises improved broadband sources for optical communication devices including waveguides, filters, switches, and photonic circuits.  While SHG can produce light over a wide spectral range, efficient SHG requires a material with a large second order nonlinear optical coefficient, such as ferroelectric oxides.  BaTiO3 (BTO) has also been shown to have excellent nonlinear optical properties. This technology utilizes polydomain epitaxial BTO to fabricate thin film waveguides, which offers potential integration of optical components in Si semiconductors.  This novel BTO waveguide structure minimizes the critical phase matching requirement for broadband SHG and offers a wider range of wavelengths using typical periodic structures.  SHG of light using BTO thin films has previously been demonstrated in the transition mode, with pump beam normal to the film surface. However, the short light interaction length offered low conversion efficiency in this mode. Utilization of this planar BTO waveguide permits light to propagate within the thin film plane, increasing the nonlinear optical interaction length, and overcomes this limitation.

Applications

• Optical communications: waveguides, filters, switches, and photonic circuits with a broadband optical response

Advantages

• Generation of visible light from 530 to 700 nm with high intensity
• Higher SHG conversion efficiency
• No requirements for critical phase matching
• Wide range of available wavelengths

IP Status

Issued US Patent No. 7,898,730