In this chapter, the optical fiber sensors based on antiresonant reflecting optical waveguide have been introduced, including the single layer, double layers, double resonators, and hybrid mechanism. Various optical fiber sensors based on antiresonant reflecting optical waveguide have been introduced in this chapter with different working principles, including the fiber optic vibration sensor, humidity sensor, strain sensor, temperature sensor, magnetic field sensor, biosensor, etc. Especially, many long-standing challenges in the fiber optic sensor can be solved through the working principle of the antiresonant reflecting optical waveguide, including the temperature cross-talk compensation, distribution localization, optofluidic biosensing, etc. In general, the optical fiber sensors based on antiresonant reflecting optical waveguide have advantages, such as compact structure, high sensitivity, large dynamic range, and high stability, which appear to have potential applications in researches of structure health monitoring, oil exploiting, and biology detection.
This chapter deals with coded modulation and impairment compensation techniques in optical fiber communication. Probabilistic shaping is a new coded modulation technology, which can reduce transmission power by precoding, reduce bit error rate and improve communication rate. We proposed a probabilistic shaping 16QAM modulation scheme based on trellis coded modulation. Experimental results show that this scheme can achieve better optical SNR gain and BER performance. On the other hand, in order to meet the demand of transmission rate of next generation high speed optical communication systems, multi-dimensional modulation and coherent detection are sufficiently applied. The imperfect characteristics of optoelectronic devices and fiber link bring serious impairments to the high baud-rate and high order modulation format signal, causes of performance impairment are analyzed, pre-compensation and receiver side’s DSP techniques designed for coherent systems are introduced.
Part of the book: Fiber Optics