News, Events & Announcements
Latest Research Areas in Focus:
- Probing coupled ferroelectric-ferromagnetic phenomena and large nonlinear optical responses in multiferroics: In-situ ultrafast nonlinear optical spectroscopy in multiferroics in the presence of external electric and magnetic fields from liquid He to 700°C.
- Hybrid Holey Fiber-semiconductor Structures: In collaboration with badding group, we are probing the nonlinear optical responses of these unusual fiber based metamaterials towards developing fast optical modulation within a fiber.
- High-Speed Optical Switches: We are developing a new class of high-speed electro-optic M x N optical switches based on domain microengineering in ferroelectrics.
Current Papers & Media Mentions:
Study Finds New Properties in "Non-Magnetic" Materials
A team of Penn State researchers has shown for the first time that the entire class of "non-magnetic" materials, such as those used in some computer components, could have considerably more uses than scientists had thought. The findings are important because they reveal previously unknown information about the structure of these materials, expanding the number of properties that they potentially could have. A material's properties, such as electrical conductivity and mechanical strength, are what determine its usefulness. The research will be published in the journal Physical Review Letters.
Bismuth Manganite Films Have Large Optical Nonlinearities
Researchers at Pennsylvania State University (University Park, PA) have tested a new candidate nonlinear optical material and deemed it good. The material, bismuth manganite (BiMnO3, or BMO), is ferroelectric. In the first optical tests of BMO, the researchers found large third-order nonlinearities and giant field-induced second-order nonlinearities.
Via pulsed-laser deposition, BMO films with thicknesses on the order of 100 nm were grown on strontium titanate substrates. A single-beam Z-scan technique using a modelocked Ti:sapphire laser was used to determine room-temperature nonlinear refractive index and absorption, which at 900 nm were -0.53 cm2/GW and -0.08 cm/kW, respectively. Electric-field enhancements of the 450-nm second-harmonic response reached three to four orders of magnitude; different experiments were done on a 100-nm BMO film, showing, for example, effective nonlinear coefficients of 40 or 115 pm/V at 300 or 473 K for applied fields of 707 or 177 V/mm, reaching enhancements of 1420 and 13,000, respectively (the latter applied field could not be boosted higher due to the larger dielectric losses at 473 K). As a result, BMO has become a potential material for optical devices such as modulators. Contact Alok Sharan at axs75@psu.edu.
