A Thesis Submitted in Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Laser Application in Physics.

Abstract

Photonic crystal fiber (PCF) has attracted a significant attention in the last few years. Guiding of the light in a PCF is governed by one of two principal mechanisms are, modified total internal reflection (MTIR) phenomenon and photonic bandgap (PBG) effect. The present work focused on the study of the spectral width change of microsecond (µs) laser pulse propagated inside hollow core photonic crystal fiber (HC-PCF). The pulse spectral width is broadened according to Kerr effect in nonlinear systems. Two wavelengths 675 and 820 nm with 30 and 200 mW average power respectively for diode lasers with three pulse durations (105, 35 and 25 µs) and three repetition rates 1, 5 and 10 KHz, have been injected to the HC-PCF. The spectral width of each laser pulse was measured at different sets of temperatures using a spectrometer. The results showed that the spectral width is changed with the temperature nonlinearly due to self phase modulation and group velocity dispersion. From the results it was concluded that the pulse spectral width is affected with the temperature, for this reason the HC- PCF may used as temperature sensor. By using the HC- PCF, the bandgap of this type of fiber and the temperature effect on its bandgap may studied in future work, also by filling the HC- PCF with blood and urine one can build biosensor.