# Editorial Board Members' Collection Series: Nonlinear Photonics
###### Abstract  
Photonics has often been defined as the key technology of the 21 st century. In recent decades, the overall trend of research and development (R&D) towards the miniaturization of devices and systems, pushed by the tremendous development of microelectronics, has led to the continuous development of micro/nanophotonic devices, which have huge potential for low-cost, scalable production, as well as the integration of high-density components [1]. On the other hand, nonlinear optical phenomena play a key role both in the knowledge of the light-matter interaction and in many fields of photonics applications [2]. The combination of integrated photonics technologies with nonlinear optics, which has led to the growth of nonlinear photonics, has also opened the way for groundbreaking new devices. Their evolution would enable advanced applications to emerge not only in optical processing and computing, but also in metrology, single-molecule sensing, imaging, microscopy, mid-infrared photonics, terahertz generation, microwave photonics, biomedicine, and quantum photonics [3]. The present Special Issue (SI) entitled \"Editorial Board Members' Collection Series: Nonlinear Photonics\", aims to highlight the current state of the art, some recent advances, and perspectives for further development. As a result, this SI contains two reviews and nine research articles, which can be divided into three groups. In the first group of papers, three papers [4, 5, 6] highlight new effects. Reference [4] focuses on nonclassical states of light, which are an essential resource for high-precision optical techniques, relying on photon correlations and noise reshaping. Efforts toward engineering the spatiotemporal profile of quantum states of light have already found great success ([4] and references therein). This article focuses, instead, on shaping the noise statistics of quantum states of light. Deviations from Brownian diffusion, known as anomalous diffusion (AnDi), occur when the mean square displacement (MSD) growth with time has an exponent other than one. AnDi is investigated in reference [5]. In disordered photonic systems, we can find examples in which light propagation exhibits subdiffusive behavior ([5] and reference therein). There are limited works reporting the modulation of chirped Gaussian soliton molecules in extra-cavity optical fiber modulation systems. Reference [6] concerns this issue and reports the theoretically simulated modulation of a soliton molecule that has an initial chirped Gaussian pulse shape in a 1 \(\upmu\)m extra-cavity optical fiber modulation system. The four papers [7, 8, 9, 10] of the second group are devoted to the hot issue of identifying efficient device integration platforms, which justifies the continuation of fundamental studies and the search for new or advanced materials with higher nonlinear coefficients and/or better overall properties. In reference [7], attention is given to graphene, which has properties that make it very promising for various applications in photonics and optoelectronics: combining graphene with other materials, one can create a variety of waveguidingdevices with better characteristics compared to waveguides made of traditional materials. In reference [8], the development of optical materials based on a nonlinear optical single crystal of lithium niobate is described. LiNbO\({}_{3}\) is a crystal state that has high nonlinear optical coefficients, which is crucial for the development of functional materials. Composite magnetic nanostructures are a subject of high research interest, as they provide several exciting effects absent in live nature. Among them, much attention has been paid to the studies of exchange coupling in antiferromagnetic/ferromagnetic (AFM/FM) films, which leads to the pinning effect. In reference [9], comparative studies of linear and nonlinear magneto-optical effects, under the laser-induced switching of the pinning effect in IrMn/CoFe films of various thickness of the ferromagnetic CoFe layer, is reported.