W. Lukosz et al., DIFFERENCE INTERFEROMETER WITH NEW PHASE-MEASUREMENT METHOD AS INTEGRATED-OPTICAL REFRACTOMETER, HUMIDITY SENSOR AND BIOSENSOR, Sensors and actuators. B, Chemical, 39(1-3), 1997, pp. 316-323
The object of the present paper is to report on new versions of the di
fference interferometer which have been sucessfully used for refractom
etric measurements and for humidity-and biosensing, i.e., for real-tim
e monitoring of the adsorption of proteins and of affinity-and immunor
eactions. The basic principle of the difference interferometers is as
follows: the TE0 and TM0 modes in a planar (or rib) waveguide are cohe
rently excited and propagate on a common path and interact with the sa
mple. The polarization-dependent interaction induces a time-dependent
phase difference Delta<(Phi)over tilde>(t) between the TE0 and TM0 mod
es, which is measured as the interferometer's response. We have develo
ped different methods to measure the phase difference a Delta<(Phi)ove
r tilde>(t). The new methods have some advantages and can be expected
to be easily extendable to multichannel (multianalyte) sensing. In the
reported experiments we use not only SiO2-TiO2 but also Si3N4 films a
s high-refractive-index waveguides on oxidized silicon wafers as subst
rates.