New materials for high gain optical limiters

Summary form only given. Practical optical limiters for use in high optical gain applications are nearing reality. These devices work principally via excited state absorption (also known as reverse saturable absorption, RSA) and are based on materials that have a large difference between the ground and excited state absorption cross sections. The ground state is nearly transparent while the excited state absorbs the incoming light strongly. Recently, we have synthesized a series of silicone substituted phthalocyanines capable of forming high optical quality pure thin films. The novelty of this class of materials is that the silicone substituents incorporate very large changes of the refractive index with temperature directly into the RSA material. Additionally, the silicone substituent yields very high solubility in many common solvents that allows the full characterization of the aggregation constant of the material. Aggregation of the phthalocyanine moieties in these materials can lead to shortened excited state lifetime, hence the degradation of the optical limiting performance. The linear, thermal, nonlinear optical and optical limiting properties of this new class of materials are described.