This book presents recent advances and trends in photonic crystal technology, making it a useful resource for students, researchers, and faculty in the field. It consists of five chapters that present in-depth knowledge of numerical methods and different applications of photonic crystal technology. The chapters discuss photonic crystals for energy, sensing, and digital devices. They also examine advanced applications of photonic crystals, like holography and photonic spin hall effect. Each chapter presents a detailed background on the considered application, recent work in the area, possible solutions to challenges, and future aspects.