From Lasing in Soft-Composite Materials to Optical Transparency in Metamaterials – Giuseppe Strangi

Date: Mon. February 21st, 2011, 4:15 pm-5:15 pm
Location: Rockefeller 301

Lasing materials range from periodic systems such as photonic crystals to partially ordered and disordered dielectric materials that scatter light diffusively. Soft materials, in particular liquid crystals, may be manipulated easily and have interesting optical properties. They are extremely promising for engineering photonic nano- structures, either as stand-alone devices or as part of innovative integrated systems. These applications can range from photonics to the bio-medical arena where miniaturized tunable laser sources may find a vast area of uses, such as optical tweezers, endoscopic sources for cancerous tissues treatment, lab-on-chip and other still yet-to- be-conceived purposes. Here, the investigation of ordered and disordered soft nano-structures to achieve compact, tunable mirror-less laser sources operating in the visible and near-IR regions is presented. The most exciting aspect of these confined systems is that optical and geometrical parameters can be modified by applying weak external fields (e.g., temperature, electric field, mechanical stress), therefore resulting in direct control of the lasing features (wavelength tunability, bandwidth, emission direction). On the other hand, random lasing in fully disordered systems having organic and inorganic nature are objects of extensive studies since the beginning of lsing materials range from periodic systems such as photonic crystals to partially ordered and disordered dielectric materials that scatter light diffusively.  Active random media have been repeatedly shown to be suitable candidates for obtaining random laser action, based mainly on the resonant feedback mechanisms in multiple scattering.  This eliminates the need for an external cavity, like in the case of regular lasers.  Light localization and interference effects that survive the multiple scattering events are invoked to explain the random lasing observed in many exotic and complex systems. The knowledge gained by exploring fundamental physical problems related to gain functionalized media has been transferred to tackle and solve the unavoidable problem of optical losses in plasmonic nanostructures.