Quantum-mechanically linking two different semiconductors could create new nonlinear optical materials
Ann Arbor, MI and New York, NY--Researchers at the University of Michigan and Queens College, City University of New York are using photons to create quantum-mechanical links between organic and inorganic semiconductors in an optical cavity; the resulting state demonstrates stronger light absorption and possibly enhanced nonlinear optical properties useful, for example, in optical switching, says Vinod Menon, associate professor of physics at Queens College.1
Organic with inorganic
To demonstrate the effect, the researchers formed an inorganic semiconductor -- zinc oxide (ZnO2) -- into nanowires, then surrounded it with an organic semiconductor -- naphthalene tetracarboxylic dianhydride (NTCDA). The two materials were chosen because their excited states are at nearly the same energies (in resonance). "What we've done is taken the excited states of two principally different materials and combined them into a new quantum-mechanical state that shares their best properties," says Stephen Forrest, professor of physics and materials science at the University of Michigan.
"Developing engineered nonlinear optical materials with properties that surpass naturally occurring materials is important for developing next-generation photonic technologies that rely on the quantum properties of light," Menon says. "For example, one could develop an optical switch that uses one photon to turn on or off the path of a second photon. This is basically a light switch that regulates light, one photon at a time -- an important building block for quantum communication and computing."
In the optical cavity, the photon "glues" together the quantum-mechanical states of the photon, the excited state of the inorganic semiconductor, and the excited state in the organic semiconductor; the result is a polariton that can efficiently transfer energy from one material to another, according to Forrest. "Uses in solar-energy conversion, light emission, and optical switching are just a few examples of applications that can benefit," he says.
Source: http://www.ns.umich.edu/new/releases/22017-photon-glue-enables-a-new-quantum-mechanical-state
REFERENCE:
1. Michael Slootsky et al., Physical Review Letters 112, 076401 (2014); doi: http://dx.doi.org/10.1103/PhysRevLett.112.076401