Nonlinear Optical Properties of Photonic Glasses

• Published in: Optical Properties of Materials and Their Applications pp. 269 - 294
• Main Author: Tanaka, Keiji
• Format: Book Chapter
• Language: English
• Published: United Kingdom John Wiley & Sons, Incorporated 2020; John Wiley & Sons Ltd
• Subjects: high‐purity inorganic glass; nonlinear absorption; nonlinear excitations; nonlinear optical properties; nonlinear refractivity; photon energy; photonic glasses; photo‐induced phenomena; semiconductor terminology; third‐order nonlinearity
• ISBN: 111950631X; 9781119506317
• DOI: 10.1002/9781119506003.ch10

This chapter defines photonic glass as a high‐purity inorganic glass that can be applied to photonics. It reviews three subjects pertaining to optical nonlinearity in photonic glasses. After a brief summary of the photonic glass, the chapter focuses on a unified understanding of the third‐order nonlinearity. Optical nonlinearity in glasses is analyzed using semiconductor terminology, which may be complementary to the dielectric approach widely employed among glass scientists. In the present scheme, the relationship among atomic structures, electronic structures, and optical absorption and refractivity spectra becomes clearer. The chapter considers the role of nonlinear excitations in photo‐induced phenomena. It is often asserted that when a photo‐induced phenomenon is induced by light of photon energy less than the bandgap, nonlinear excitation takes place. However, this may be a hasty conclusion, because it neglects midgap states, whose existence is inherent to the glasses.