## 1 Introduction  
Guided wave ultrasound is increasingly being used to solve inspection problems in a wide variety of applications. This is because guided waves can be used to inspect over long distances from a single probe position, offer complete volumetric coverage, and can inspect hidden/inaccessible structures, such as those under water, coatings, insulation, and soil. Before discussing the merger of ultrasonic guided waves with fiber optic technology, the major topic in this paper, a brief review of some of our first accomplishments on various topics in ultrasonic guided waves is presented. This illustrates the background leading to the topic of this paper. Two textbooks on the subject of wave mechanics fundamentals with emphasis on guided waves for nondestructive testing (NDT) and structural health monitoring (SHM) are presented by [PERSON], [1] 1999, [2] 2014. Some selected developments over the last few decades include the following. The value of computing and selecting specific wave structures from the phase velocity dispersion curves was initially pointed out by [PERSON], [PERSON], and [PERSON] [3] 1991, where defects close to a surface were found with wave structure having lots of energy near the surface. Since then paying attention to wave structure has led to solutions for many important problems in NDT and SHM. [PERSON], [PERSON], and [PERSON] in [4] 1993, demonstrated the ability to locate wave structure profiles with in-plane displacement on the surface of a waveguide, which has played a significant role in ice detection and the impact of water loaded surfaces on many NDT and SHM problems. A variety of problems in the aircraft industry are covered by [PERSON] and [PERSON] [5] 2000. Such topics as lap joint, tear strap and honeycomb inspection are discussed. A method of focusing ultrasonic guided waves in pipe was introduced by [PERSON], [PERSON], [PERSON], and [PERSON] [6] 2003. The phased array focusing approach improves detection sensitivity, axial and lateral resolution and even penetration power. The ability to generate dispersion curves for structures having an arbitrary cross section was introduced by [PERSON], [PERSON], and [PERSON] [7] 2003. Many new applications with guided waves became possible and in particular a breakthrough in treating guided wave propagation in rails. Guided wave tomography concepts and several sample problems were covered by [PERSON], [PERSON], and [PERSON] [8] 2005. The critical problem of rail inspection under shelling for transverse crack detection in the rail head along with possibilities of web and base defect detection was presented by [PERSON], [PERSON], and [PERSON] [9] 2008. Adhesive bonding inspection breakthroughs was reported for certain substrate systems by [PERSON] and [PERSON] [10] 2010. Utilization of magnetostrictive technology advancements for the generation and utilization of guided waves was reported by [PERSON], [PERSON], [PERSON], and [PERSON] [11] 2013. Guided wave mode and frequency tuning and optimization is discussed in [PERSON] and [PERSON] [12] 2014, making it possible to find defects in a variety of different structures more completely. A phased array system for plate inspection was developed and reported by [PERSON], [PERSON], [PERSON], and [PERSON] [13] 2017. This technique is responsible for amazingly fast inspection of corrosion type defects in large plate-like structures employing radar type circumferential or sector scans. Other NDT applications for guided waves, for example, include oil-tank weld detection using EMAT-generated shear-horizontal guided waves [14] 2017, fundamental torsional mode detection of angled cut flaws [15] 2016, and liquid level displacement measurements using magnetostrictive sensors [16] 2017. Our background in ultrasonic guided waves thus prepared us for a merger with concepts presented by [PERSON], [PERSON], and [PERSON] [17] 2001. [PERSON] et al. [17] showed the possibility of ultrasonic wave interaction with fiber Bragg gratings (FBG) in an optical fiber.