Flexible multilayer substrate based optical waveguides: Applications to optical sensing

• Compatible and adjustable flexible multilayer substrate based optical waveguide.
• Young's modulus and thickness of the substrates are engineered and regulated.
• Substrate itself also serves as a thin-film optical waveguide.
• Innovative fabrication procedure for waveguides with bracing structures.
• Capability for manufacturing error insensitive or high sensitivity accelerometers.

The performance of flexible waveguides based microsystems such as optical waveguide sensors or a lab-on-a-chip platform is closely related to the parameters of the waveguides and substrates. In order to achieve enhanced performance of microsystems, we proposed a concept of flexible multilayer substrate based waveguides. We show that the mechanism properties of the flexible substrates and waveguides including the Young's modulus and the structural thickness can be well engineered and regulated by ranging the configuration of the multilayers with different materials. The multilayer substrate itself can also serve as a thin-film optical waveguide. The experimental results show that this structure is suitable for developing optical sensor chips like double-ring resonator based accelerometers. As an example, the theoretical analysis based on the tunable Young's modulus and thickness of the waveguides also provides an approach to achieve manufacturing error insensitive or accelerometer chips with different sensitivities between 10 per g and 53 per g. The sensitivity will be tenfold if propagation loss of the waveguides is reduced from 1.9 dB/cm to 0.3 dB/cm. This tunable structure promises to meet the requirements of various sensors and lab-on-a-chip systems for displacement, chemistry or biology measurements.