Temperature-Insensitive Biochemical Sensor And All-Optical Switching Based On Fiber Gratings

Because of its excellent properties, optical fiber grating is a hot research in the recent years. And now it has been widely applied in all-optical communications, optical sensors and many other fields. Temperature-insensitive biochemical fiber Bragg grating sensor, as well as nonlinear all-optical switching based fiber gratings is focused on. The present paper has done the work as follows:1. The error of sensing affected by temperature is discussed. The results show that the sensor sensitivity is affected by temperature through both the FBGs and the refractive index of chemical solutions change. The relationship between wavelength shift with temperature changes is obtained by numerical calculation. A scheme of temperature-insensitive chemical sensor based on FBGs is designed. Different methods of compensation to low and high concentration solutions with half grating etched are applied.2. A theoretical model of the all-optical switching of using Bragg grating in a highly nonlinear photonic crystal fiber is established through analyzing the model of cross phase modulation (XPM). Based on the theoretical model, numerical model is investigated and realized by using differential method-obvious scheme. The parameters influencing the characters of the switching are discussed.3. The normalized nonlinear coupled mode equation in long period fiber grating (LPFG) is numerically calculated with slit-step Fourier and explicit Runge-Kuta methods. The nonlinear propagation in long period fiber grating with low and high intensity incident in two typical cases (on-resonance case and off-resonance case) is obtained. The output light intensity in core with incident intensity changes shows that, the switching performance of LPFG is off to on in on-resonance case, as well as on to off, and then to on in off-resonance case.