Rongping Wang

1.8-10 μm mid-infrared supercontinuum generated in a step-index chalcogenide fiber using low peak pump power

By pumping an 11-cm-long step-index chalcogenide fiber with ∼330u2009u2009fs pulses at 4.0xa0μm from an optical parametric amplifier, mid-infrared supercontinuum generation spanning from ∼1.8 to ∼10u2009u2009μm within a dynamic range of ±15u2009u2009dB has been demonstrated at a relatively low power threshold of ∼3000u2009u2009W.

Properties of GexAsySe1-x-y glasses for all-optical signal processing.

We present a systematic study of Ge(x)As(y)Se(1-x-y) bulk chalcogenide glasses to determine the best composition for fabricating all-optical devices. The dependence of physical parameters such as the band-gap, glass transition temperature and third order optical nonlinearity (n(2)) on composition has been studied and a relation between the bond-structure and elevated linear loss levels in high Germanium glasses has been identified. It is found that glasses with 11

Mid-infrared supercontinuum generation in chalcogenides

Yi Yu acknowledges the financial support from the China Scholarship Council for her PhD nScholarship No. 201206110048. This research was conducted by the Australian Research nCouncil Centre of Excellence for Ultrahigh Bandwidth Devices for Optical Systems (project nnumber CE110001018). Dr Zhiyong Yang is supported by ARC DECRA project nDE120101036 and Dr Duk-Yong Choi by ARC Future Fellowship FT110100853.

Progress in optical waveguides fabricated from chalcogenide glasses

We review the fabrication processes and properties of waveguides that have been made from chalcogenide glasses including highly nonlinear waveguides developed for all-optical processing.

Systematic z-scan measurements of the third order nonlinearity of chalcogenide glasses

We report measurements of the third order optical nonlinearity of 51 chalcogenide glasses in the near infrared. Substituting more polarizable elements (Se for S, Sb for As) into the glasses increased their nonlinearity but also reduced the optical bandgap increasing two-photon absorption. Overall the measured values are an extremely good fit to the semi-empirical Miller’s rule whilst the normalized real and imaginary parts are in satisfactory agreement with the scaling for indirect gap semiconductors reported by Dinu. At 1550nm we find that there is an upper limit to the nonlinearity of ≈10−13cm2/W above which two-photon absorption becomes significant.

Supercontinuum generation in the mid-infrared from a dispersion-engineered As2S3 glass rib waveguide.

We report the generation of a mid-infrared supercontinuum created by ≈7.5 ps duration pulses at 3260 nm passing through a dispersion engineered As(2)S(3) rib waveguide. The threshold for a 6.6 cm long waveguide was around 800 W and at 1700 W the spectrum extended from ≈2.9-4.2 μm and was limited on the long wavelength side by absorption in the cladding of this particular waveguide.

Phase change behaviors of Zn-doped Ge2Sb2Te5 films

Zn-doped Ge2Sb2Te5 phase-change materials have been investigated for phase change memory applications. Zn15.16(Ge2Sb2Te5)84.84 phase change film exhibits a higher crystallization temperature (∼258u2009°C), wider band gap (∼0.78u2009eV), better data retention of 10 years at 167.5u2009°C, higher crystalline resistance, and faster crystallization speed compared with the conventional Ge2Sb2Te5. The proper Zn atom added into Ge2Sb2Te5 serves as a center for suppression of the face-centered-cubic (fcc) phase to hexagonal close-packed (hcp) phase transition, and fcc phase has high thermal stability partially due to the bond recombination among Zn, Sb, and Te atoms.

Annealing induced phase transformations in amorphous As2S3 films

Amorphous arsenic sulphide (As2S3) films prepared by ultrafast pulsed laser deposition have been vacuum annealed at a range of different temperatures. Measurements of the glass transition temperature indicate that a crystallization process initiates at annealing temperatures around 170°C. In combination with Raman scattering analysis, we conclude that phase separation is intrinsic for our as-deposited films. During annealing two sorts of phase transformation are identified: one between different amorphous polymorphs, and another from the amorphous to a crystalline state. We point out a correlation between these two types of transformation and two characteristic time scales identified from measurements of the relaxation of the refractive index, and explain the Arrhenius and non-Arrhenius behaviors leading to the observed temporal characteristics.

Rebonding of Se to As and Ge in Ge33As12Se55 films upon thermal annealing: Evidence from x-ray photoelectron spectra investigations

This research was supported by Australian Research nCouncil through its Centers of Excellence, Discovery and nFederation Fellow Programs.

Observation of two elastic thresholds in GexAsySe1−x−y glasses

This research is supported by the Australian Research nCouncil through its Centres of Excellence and Federation nFellow Programs.