Jaakko Aarnio

Survivable WDM/SDM ring for metropolitan networks

We present a new survivable, reconfigurable wavelength division multiplexing (WDM) ring architecture for the metropolitan area or regional networks. It uses bi- directional WDM and space division multiplexing with simple switches for 1 + 1 protection at optical channel layer. The ring can be realized with available technology at relatively low cost. This architecture has advantages in scalability and reconfigurability. Achievable ring sizes are studied, and adaptability to varying traffic needs, utilizing multi-hop connections, is evaluated.

Integrated optical ring resonator on silicon with thermal tuning and in-situ temperature measurement

Small size ring resonators with ring diameter of 2 mm are fabricated using silicon nitride waveguides on silicon. The small diameter of the ring allows a large free spectral range of 26 GHz. Doped polysilicon is used as thermo-optic heating element to temperature tune and ring resonator. A poly-Si resistor is used for the first time as a thermistor to measure the waveguide temperature. The temperature coefficient of the poly-Si thermistor is measured to be 9.5 X 10-4/ degree(s)C. The finesse of the ring resonator is 68 and the contrast 46%. The propagation loss of the silicon nitride rib waveguide is 0.1 dB/cm at 1312 nm. The temperature coefficient of the optical path length of the waveguide is 1.5 X 10-5/ degree(s)C.

Integrated optics in biosensor design

Optical sensing techniques have obtained remarkable attention in developing biosensors. Especially, methods based on evanescent field probing are suitable for direct immunosensing. However, miniaturized immunosensors are more difficult to realize when compared with catalytic sensors. Miniaturization and the small amounts of reagents will speed up detection but they are also a potential source of errors and instability. Different aspects of miniaturization of immunosensors are discussed. Some modeling methods of the optical biosensing interface are presented. Modeling is important, but there is a lack of detailed optical data of biomolecules. Two integrated optics detectors are described and their use in biosensing applications are evaluated.