Strengthened glass by ion exchange, mechanical and optical properties: perspectives and limits of glass as a substrate for flexible photonics

Flexible photonics is an emerging technology in photonics applications. The availability of ultra thin glasses with thicknesses raging from tens to hundreds of microns is an appealing opportunity to be considered for flexible photonics applications substrates. The increase in mechanical characteristics, specifically strength, for such glasses is achieved by specific chemical compositions and ion exchange processes. The main physical effects to be considered are the introduction of residual stress profiles and refractive index modifications. Both aspects may interfere with flexible photonics applications of these glass substrates. There will be discussed the underpinning physics of stress build up and relaxation and how these effects may affect refractive index. The discussion will be mainly focused to the most promising glass chemical compositions already widely used in consumer electronics applications that is sodium aluminosilicates.