This paper presents a study on unidirectional invisibility induced by PT-symmetric periodic structures. The authors show that near the spontaneous PT-symmetry breaking point, PT-symmetric Bragg periodic structures can act as unidirectional invisible media. In this regime, reflection from one end is diminished while it is enhanced from the other. The transmission coefficient and phase are indistinguishable from those expected in the absence of a grating. The phenomenon is robust even in the presence of Kerr nonlinearities and can effectively suppress optical bistabilities. PT-symmetric structures exploit parity (P) and time (T) symmetry to achieve new functionalities and optical characteristics. These structures allow for controlled photon creation and absorption, resulting in zero net loss or gain. In optics, PT symmetry requires the complex refractive index to obey the condition n(r) = n*(-r), meaning the real part is even and the imaginary part is odd. PT-synthetic materials exhibit features such as power oscillations, absorption-enhanced transmission, double refraction, and non-reciprocity of light propagation. The study explores the possibility of synthesizing PT-symmetric objects that become unidirectionally invisible at the exceptional points. The invisibility arises from spontaneous PT-symmetry breaking, achieved through a combination of optical gain and loss regions and index modulation. The authors consider scattering from PT-synthetic Bragg structures and investigate the consequences of PT symmetry in the scattering process. They find that at the PT-symmetric breaking point, the system is reflectionless over all frequencies around the Bragg resonance when light is incident from one side, while the reflectivity is enhanced from the other side. The transmission phase vanishes, a necessary condition for evading detectability. These effects persist even in the presence of Kerr nonlinearities. The authors demonstrate these effects using an optical periodic structure with a PT-symmetric refractive index distribution. They show that the transmission and reflection coefficients are affected by the detuning and the size of the sample. At the Bragg point, the transmission is identically unity, while the reflection for left incident waves is zero. The phase of the transmission amplitude is zero, making interference measurements unable to detect the periodic structure. The study also investigates the robustness of the phenomena in the presence of Kerr nonlinearities. The results show that unidirectional invisibility persists and non-reciprocal transmission is possible. The authors conclude that the phenomenon of unidirectional invisibility of PT-periodic systems at the exceptional point is unaffected by the presence of Kerr nonlinearities. The study highlights the potential of PT-symmetric structures for applications in optical devices and materials.This paper presents a study on unidirectional invisibility induced by PT-symmetric periodic structures. The authors show that near the spontaneous PT-symmetry breaking point, PT-symmetric Bragg periodic structures can act as unidirectional invisible media. In this regime, reflection from one end is diminished while it is enhanced from the other. The transmission coefficient and phase are indistinguishable from those expected in the absence of a grating. The phenomenon is robust even in the presence of Kerr nonlinearities and can effectively suppress optical bistabilities. PT-symmetric structures exploit parity (P) and time (T) symmetry to achieve new functionalities and optical characteristics. These structures allow for controlled photon creation and absorption, resulting in zero net loss or gain. In optics, PT symmetry requires the complex refractive index to obey the condition n(r) = n*(-r), meaning the real part is even and the imaginary part is odd. PT-synthetic materials exhibit features such as power oscillations, absorption-enhanced transmission, double refraction, and non-reciprocity of light propagation. The study explores the possibility of synthesizing PT-symmetric objects that become unidirectionally invisible at the exceptional points. The invisibility arises from spontaneous PT-symmetry breaking, achieved through a combination of optical gain and loss regions and index modulation. The authors consider scattering from PT-synthetic Bragg structures and investigate the consequences of PT symmetry in the scattering process. They find that at the PT-symmetric breaking point, the system is reflectionless over all frequencies around the Bragg resonance when light is incident from one side, while the reflectivity is enhanced from the other side. The transmission phase vanishes, a necessary condition for evading detectability. These effects persist even in the presence of Kerr nonlinearities. The authors demonstrate these effects using an optical periodic structure with a PT-symmetric refractive index distribution. They show that the transmission and reflection coefficients are affected by the detuning and the size of the sample. At the Bragg point, the transmission is identically unity, while the reflection for left incident waves is zero. The phase of the transmission amplitude is zero, making interference measurements unable to detect the periodic structure. The study also investigates the robustness of the phenomena in the presence of Kerr nonlinearities. The results show that unidirectional invisibility persists and non-reciprocal transmission is possible. The authors conclude that the phenomenon of unidirectional invisibility of PT-periodic systems at the exceptional point is unaffected by the presence of Kerr nonlinearities. The study highlights the potential of PT-symmetric structures for applications in optical devices and materials.