New optical detection techniques for chemical sensors

In this work we present three novel optical approaches towards the implementation of bio- and chemical sensors. First we describe an absorbance spectroscopic technique developed on a waveguide platform that features a sensitivity enhancement of 4 orders of magnitude compared to the conventional transmission measurements of ultra-thin films. Next we show a waveguide Zeeman interferometric technique, which is based on the relative phase change between the TE and TM waveguide modes, applied as a sensor platform. Finally an external-cavity laser, a semiconductor laser combined with a single mode optical fiber and a Bragg grating reflector, was built to work as an active sensor where the analyte species were incorporated inside the resonant cavity to increase sensitivity.