W. V. Schoenfeld

Learn More
Quantum communication relies on the availability of light pulses with strong quantum correlations among photons. An example of such an optical source is a single-photon pulse with a vanishing probability for detecting two or more photons. Using pulsed laser excitation of a single quantum dot, a single-photon turnstile device that generates a train of(More)
We report on the observation of photoluminescence from positive, neutral and negative charge states of single semiconductor quantum dots. For this purpose we designed a structure enabling optical injection of a controlled unequal number of negative electrons and positive holes into an isolated InGaAs quantum dot embedded in a GaAs matrix. Thereby, we(More)
The characteristics of an acceptor level in Sb-doped, p-type ZnO were studied using cathodoluminescence ͑CL͒ spectroscopy as a function of hole concentration. Variable-temperature CL measurements allowed us to estimate the activation energy of an Sb-related acceptor from temperature-induced decay of CL intensity. The values of activation energy of about(More)
We study optically single self-assembled quantum dots embedded within the wide quantum well of a mixed type quantum structure. We compare the steady state and pulsed photoluminescence spectra of these dots to those of previously studied " regular " dots. We unambiguously identify experimentally emission from various discrete charge state of the dots. We(More)
Arsenic trisulfide (As 2 S 3) is a chalcogenide (ChG) material with excellent infrared (IR) transparency (620 nm to 11 μm), low phonon energies, and large nonlinear refractive indices. These properties directly relate to commercial and industrial applications including sensors, photonic waveguides, and acousto-optics. Multi-photon exposure can be used to(More)
—This paper addresses the calculation of internal back reflectance for various dielectrics that are used in rear-side pas-sivated crystalline silicon solar cells. Optical modeling of various stack configurations is examined to explore the back-surface re-flectance at the Si–dielectric interface for different film combinations and thicknesses as a function(More)
Progress in materials for radical initiated, radical inhibited superresolution lithography is reported. The pho-tochemistry and optical system is described, with a brief discussion on the theory of operation. A motivation is presented for developing a new material that may be used as a spinnable photoresist, and qualitative resist requirements are(More)
We present a practical method to determine femtosecond laser induced refractive index changes in transparent materials. Based on an iterative Fourier transform algorithm, this technique spatially resolves the refractive index of complex structures by combining the dimensions of the modified region with the corresponding phase change extracted from far-field(More)
  • 1