Development of Photonic Crystal Fiber Based Gas/ Chemical Sensors

The development of highly-sensitive and miniaturized sensors that capable of real-time analytes detection is highly desirable. Nowadays, toxic or colorless gas detection, air pollution monitoring, harmful chemical, pressure, strain, humidity, and temperature sensors based on photonic crystal fiber (PCF) are increasing rapidly due to its compact structure, fast response and efficient light controlling capabilities. The propagating light through the PCF can be controlled by varying the structural parameters and core-cladding materials, as a result, evanescent field can be enhanced significantly which is the main component of the PCF based gas/chemical sensors. The aim of this chapter is to (1) describe the principle operation of PCF based gas/ chemical sensors, (2) discuss the important PCF properties for optical sensors, (3) extensively discuss the different types of microstructured optical fiber based gas/ chemical sensors, (4) study the effects of different core-cladding shapes, and fiber background materials on sensing performance, and (5) highlight the main challenges of PCF based gas/ chemical sensors and possible solutions

Performance failure analysis of EDFA cascades in optical DWDM packet-switched networks

WOS: 000184208700004A simple and comprehensive technique to determine the probability that a cascade of erbium-doped fiber amplifiers (EDFAs) may be driven into unacceptable regimes of bit error rate (BER) and/or gain levels is presented. This technique allows network designers to determine the tolerances by which,the signal power levels may deviate from their predesigned average values and still give acceptable gain variances and BERs at the receiver. We show that even in the signal power range well above the receiver sensitivities (- 38, dBm/ch) where the gain spread is not significant, the corresponding spread in BER due to random arrival of packets might,result in unacceptable performance. We show for typical levels of operation, the BER temporarily (for about 3 mus) deviates to below 10(-9) (10(-15)) with a probability of 10(-3) (10(-2)), for 100 (64) channels. We show that the gain spread for a single EDFA can be negligible for a range of signal and pump powers at a given average gain