Lithographically tuned one dimensional polymeric photonic crystal arrays

Abstract

One-dimensional polymeric photonic crystal (PC) arrays with tuned bandgap properties are designed and fabricated on the same substrate by employing mainstream micropatterning technologies and appropriate photopatternable materials. The two photopatternable materials are based on poly (2-hydroxy ethyl methacrylate) and epoxy polymers with the addition of appropriate photoacid generators and are diluted in orthogonal solvents, ethyl lactate and PGMEA respectively. The tuning of the photonic band gap of each photonic crystal is achieved through carefully tuned lithographic processing conditions with emphasis in low-lithographic contrast operation and gray scale lithography. By applying sequential lithographic steps in orthogonal developers one-dimensional photonic crystal arrays with 10 bi-layers are fabricated with very well defined patterns. With this approach, PC arrays with four distinct areas are realized on the same Si substrate with tuned reflectance spectrum covering the whole visible spectral regime.