H. Zeng

Nonlinear photoluminescence of fullerene-doped optical glasses

Strong broadband white photoluminescence was observed in fullerene-doped phosphate and fluorophosphate optical glasses irradiated by an ultraviolet laser. Microphotoluminescence measurements demonstrated the existence of microislands in those amorphous glasses, where fullerene dopants provided high photosensitivity and optical nonlinearity. Nonlinear photoluminescence was observed under ultralow continuous-wave laser excitations. The photoluminescence peak wavelengths were demonstrated to depend nonlinearly on the laser excitation power.

Optical limiting and bistability of a σ–π photoconductive copolymer

Abstract Optical nonlinearity of a σ–π photoconductive copolymer, poly(disilanylene-2,2 ′ -bipyridine-5,5 ′ -diyl) ruthenium complex, has been investigated in chloroform solution of various concentrations. The nonlinear optical absorption resulted in optical limiting, optical bistability, and laser pulse compression for nanosecond pulses at the wavelength of 532 nm. Theoretical analyses showed that the optical absorptive nonlinearity was dependent on the photogenerated excitons and exciton–exciton couplings.

Experimental quantum state engineering with time-separated heraldings from a continuous-wave light source: A temporal-mode analysis

Conditional preparation is a well-established technique for quantum state engineering of light. A general trend is to increase the number of heralding detection events in such realization to reach larger photon-number states or their arbitrary superpositions. In contrast to pulsed implementations, where detections only occur within the pulse window, for continuous-wave light the temporal separation of the conditioning detections is an additional degree of freedom and a critical parameter. Based on the theoretical study by A.E.B. Nielsen and K. Molmer and on a continuous-wave two-mode squeezed vacuum from a nondegenerate optical parametric oscillator, we experimentally investigate the generation of two-photon state with tunable delay between the heralding events. The present work illustrates the temporal multimode features in play for conditional state generation based on continuous-wave light sources.

Optical properties of microstructures in fullerene-doped optical glasses

Microphotoluminescence and second-harmonic microscopy were used to study islands formed inside phosphate and fluorophosphate optical glasses with fullerene dopants. Scanning microphotoluminescence and second-harmonic microscopy indicated that fullerene dopants are subjected to strong influence from the glass matrix, which causes distortion of molecular symmetry, enhancement of fluorescence, and occurrence of noncentrosymmetry required by the macroscopic second-order optical nonlinearity.

A novel ring laser resonator of linear geometry with twin off-axially cut Nd:YVO4

Abstract A ring laser resonator is realized in a compact linear configuration with a twin-Nd:YVO 4 device formed by a pair of off-axially cut Nd:YVO 4 crystals, which are closely packed with their optical axes being rotated 90° from each other. In a linear resonator with a twin-Nd:YVO 4 device sandwiched by two intra-cavity quarter-wave plates, laser beams can circulate in the twin-Nd:YVO 4 device. Due to spatial walk-off resulted from birefringence within the twin-Nd:YVO 4 device, the spatial modulation of laser gain is eliminated. A stable IR output of 51 mW at 1064 nm is obtained with a pump power of 581 mW at 809 nm. The threshold pump power is 207 mW, and laser slope efficiency is 13.6%. Stable green light can also be obtained by temperature-controlling the intra-cavity nonlinear crystal KTP as a quarter-wave plate to replace one of the intra-cavity quarter-wave plates.

Interaction of femtosecond filaments and coalescence of noncollinear filaments into high-peak-intensity photonic crystal waveguides

Photonic crystal filaments were demonstrated with noncollinear filaments interaction, resulting in elongated filaments and third harmonic generation of more than two orders enhancement as compared with that from a single filament.

Multi-filamentation dynamics of ultrashort laser pulse in pre-aligned molecules

By using field-free molecular alignment, we demonstrate the multi-filaments of ultrashort laser pulse with input spatial ellipticity can be suppressed to be a single core, or be controlled to various structures with modulated spectra.