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Limitations imposed on the saturation energy of high-power slab-coupled optical waveguide amplifiers were studied for pulsed signal transmission. Loss due to the two-photon absorption and free-carrier absorption processes becomes a dominant factor for ultrashort-pulse amplification, leading to lower saturation energy. TPA and FCA coefficients are measured to be 65 cm/GW and 7times10-17 cm2, respectively...
We propose an optical phase noise extraction and amplification (OPNEA) technique. By applying OPNEA to phase noise monitoring for (D)PSK, 13-dB dynamic range and 0.2-dB/degree sensitivity were achieved with a 50-120-degree phase deviation.
We have developed a simple yet rigorous theory of the enhancement of photoluminescence (PL) efficiency in the vicinity of metal nanoparticles that takes into account the enhancement during optical absorption and emission. Using an example of active InGaN quantum dots (QDs) positioned in close proximity to Ag nanospheres embedded in GaN, we show that strong enhancement can be obtained only for those...
Advances in Optical Coherence Tomography will be discussed. Sensitivity advantages of Spectral or Fourier Domain and Optical Frequency Domain Imaging or Swept Source OCT will be explained, and examples of clinical applications will be presented.
We numerically analyze phase-sensitive parametric amplification of a multi-pixel text image and demonstrate that ~10-dB gain is achievable with ~10-kW total pump peak power, which makes it compatible with compact pump sources.
We demonstrate high resolution near-field imaging of the optical modes profile in high Q silicon microdisks. A spatial resolution of ~20 nm is obtained by characterizing the perturbative effects of a scanning AFM tip on the microdisk transmission.
Optical implementations of synthetic aperture imaging techniques provide a method of overcoming the platform constrained diffraction limit for optical imaging systems. We discuss progress in applying these methods to outdoor imaging demonstrations.
A hyperspectral tomography sensor has been developed to measure the distribution of temperature and chemical species. The spatial and temporal resolution enabled by this sensor is expected to resolve key issues in practical combustion devices.
A full-color pixel consisting of CdSe, ZnO, and CdS nanowires has been heterogeneously integrated on a substrate with lithographic accuracy using lateral optoelectronic tweezers (LOET). Red (CdSe, 685 nm), blue (CdS, 496 nm), and green (ZnO, 518 nm) light emissions are obtained by selectively pumping the corresponding nanowires. Potentially the nanowires can be directly assembled on CMOS driver circuit...
We propose new second-harmonic-generation probes of surface chirality, based on circular polarizations or handed superpositions of radial and azimuthal polarizations. Because of normal incidence focusing, the techniques are not sensitive to anisotropy.
We present an experiment where the motion of a silicon micro-mechanical resonator is optically monitored in a high-finesse cavity with a quantum-limited sensitivity. Directs effects of intracavity radiation pressure are experimentally demonstrated. Further experimental progress and cryogenic operation may allow for quantum optics experiments and lead to the experimental observation of the quantum...
We measured the photoconductivity in P3HT excited above and below the band gap using OPTP spectroscopy and extracted values consistent with the intrinsic mobility. We have also investigated the advantages of broadband (> 5 THz) spectroscopy.
The two-photon absorption cross-sections of two novel derivatives of 5,5'-bis(diphenylphosphino)-2,2'-bithiophene have been measured using Z scans employing 27-ps pulses at multiple pulse energies, yielding values of 1500 plusmn 50 GM and 2830 plusmn 50 GM.
Both femtosecond and nanosecond laser pulses can produce nonlinear effects in water, including filamentation and laser-induced breakdown resulting in acoustic generation. We examine the effects of GVD, varying wavelength, bandwidth, energy, and focusing configurations.
Temperature dependent two-photon and free-carrier absorption spectra of InSb are measured using a tunable picosecond source via temperature controlled Z-scan experiments and show good agreement with theoretical predictions. Three-photon absorption is also observed.
We report on time resolved studies of V2O3 which is a correlated electron material that undergoes a metal-insulator transition at ~150 K. We observe coherent oscillations in the terahertz conductivity following excitation with 35-fs optical pulses.
We present ultrafast optical-pump THz-probe measurements of the carrier intraband relaxation and interband recombination dynamics in oriented Germanium nanowires. We find 2-3 ps intraband relaxation times and density-dependent recombination times in the 50-100 ps range at 300 K.
A Fabry-Perot etalon is used to form a novel type of microphone. Refractive index dependant transmission is proportional to sound pressure over a large dynamic range. The current of the laser diode is tuned to take into account environmental influences.
General design principles for developing space based diode pumped solid state laser systems will be presented. Major issues affecting the design, development, system engineering, ground testing, operational simplicity and long term reliability will be discussed.
Quantum rods (QRs) are incorporated into polymers that are doped with azo dyes via an energy transfer process. The polarization-dependent refractive-index change allows four-dimensional optical data storage as well as other polarization-controlled photonic applications.
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