**Author details**

**Figure 10.** LPG transmission spectra simulated for an optic fiber in normal state. LPG period = 400 μm, LPG length *L* =

**Figure 11.** LPG transmission spectra simulated for a bent optic fiber in normal state. LPG period = 400 μm, LPG length

Results obtained in the analyzed LPG cases are presented in **Figures 9**–**11**. In **Figure 9** are presented simulation results obtained regarding the variations of the resonance wavelengths of the absorption peaks in the LPG transmission spectra, peaks defined using (16)-the "second key task to be accomplished" in the design of LPG fiber sensors. In **Figures 10** and **11** are presented the LPG transmission spectra simulated for an unperturbed fiber and for a bent

The chapter refers to a broad research domain concerning the optic fiber and fiber grating physics. One of the two main purposes of the chapter consists in presenting the theoretical tools and simulation procedures used for analysis of optical properties of short-period FBG and fiber LPG. The second purpose of the chapter consists in providing the basics of simulation models. Examples of simulation results obtained using coupled-mode theory, verified using

75 mm, grating amplitude ∆ *neff* = 25e−4.

110 Modeling and Simulation in Engineering Sciences

*L* = 75 mm, grating amplitude ∆ *neff* = 25e−4.

fiber.

**4. Conclusions**

Dan Savastru\* , Sorin Miclos, Marina Tautan and Ion Lancranjan

\*Address all correspondence to: j\_j\_f\_l@yahoo.com

National Institute of Research and Development for Optoelectronics, Magurele, Ilfov, Romania
