Optical bio-sensors based on etched fiber Bragg gratings

need for efficient detection of biochemical agents is becoming more compelling. High sensitivity chemical and biological sensors, based on etched core fiber Bragg gratings that detect change in the index of refraction of surrounding solutions, were developed to measure the index of refraction of different solutions. A sensitivity of 1394 nm/riu was achieved for a core diameter of 3.4,mu m. 6 Assuming an experimental wavelength resolution of 0.01 nm, we were able to detect an index change of 7.2 center dot 10(-6) These chemical sensors, properly sensitized using common glutaraldehyde chemistry, can be effectively used as biosensors. A 20 base single stranded DNA of concentration of 0.7 mu g/ml was successfully detected. Some ideas are also proposed for sensitivity improvement of the sensor, like using the higher order modes. It is shown that the higher order modes can also provide information about the cause of the fundamental shift, whether it is due to refractive index change or due to external effects like temperature and stress.