The Internet Goes to College

Presents findings from a survey of college students at a wide range of 2-year and 4-year public and private colleges and universities. Looks at the impact of Internet usage on students' academic and social routines

Very low loss reactively ion etched Tellurium Dioxide planar rib waveguides for linear and non-linear optics

We report on the fabrication and optical properties of the first very low loss nonlinear Tellurite planar rib waveguides ever demonstrated. A new reactive ion etch process based on Hydrogen as the active species was developed to accomplish the low propagation losses. Optical losses below ~0.05dB/cm in most of the NIR spectrum and ~0.10dB/cm at 1550nm have been achieved - the lowest ever reported by more than an order of magnitude and clearly suitable for planar integrated devices. We demonstrate strong spectral broadening of 0.6ps pulses in waveguides fabricated from pure TeO2, in good agreement with simulations

Low loss high index contrast nanoimprinted polysiloxane waveguides

Nanoimprint lithography is gaining rapid acceptance in fields as diverse as microelectronics and microfluidics due to its simplicity high resolution and low cost. These properties are critically important for the fabrication of photonic devices, where cost is often the major inhibiting deployment factor for high volume applications. We report here on the use of nanoimprint technology to fabricate low loss broadband high index contrast waveguides in a Polysiloxane polymer system for the first time

980nm pumped erbium doped tellurium oxide planar rib waveguide laser and amplifier with gain in S, C and L band

A thin film based erbium doped tellurium oxide (TeO₂) waveguide amplifier producing gain from 1500nm to 1640nm when pumped at 980nm is demonstrated. At measured internal gains exceeding 14dB lasing due to end facet reflection set in producing the first tellurite waveguide laser. High gains were observed despite significant upconversion, whose impact appears to be mitigated to some extent by residual OH contamination. The device displayed no photosensitive effects from either the high pumping intensities used or the intracavity intensity at 1550nm.This work was funded by the Australian Research Council mainly via Discovery Project DP0987056 and partly through the Centre for Ultrahigh bandwidth Devices for Optical Systems (CUDOS) CE110001018

Thermal annealing of arsenic tri-sulphide thin film and its influence on device performance

Arsenic tri-sulphide (As₂S₃)thin filmwaveguides have been used successfully as nonlinear optical devices for all-optical signal processors. For such devices, low propagation loss is vital if high performance is to be obtained. In this study, thermal annealing was employed not only to stabilize the physical properties of the films, but also to reduce the sources of light attenuation in the as-deposited material. Here we investigated heat-induced changes to the microstructure and optical properties of As₂S₃thin films and, based on this information, determined the best annealing conditions. The refractive index of the films rises with annealing due to thermal densification and increased heteropolar bond density. The growth of surface roughness and thermal stress in the film, however, limits the annealing temperature to ∼130 °C. We fabricated and analyzed waveguides produced from as-deposited and annealedfilms and found that the propagation loss of the guides dropped by ∼0.2 dB/cm as a result of appropriate annealing.Rayleigh scattering and absorption from defects associated with phase separation, homopolar bonds, voids, and dangling bonds in the as-deposited film are shown to contribute to the higher light attenuation in unannealed films.This research was supported by the Australian Research Council through its Centre of Excellence program

Stoichiometric Low Loss Tellurium Oxide Thin Films for Photonic Applications

Stoichiometric low loss Tellurium Oxide, TeO2, films have been produced by reactive RF sputtering. TeO2 films with propagation loss below 0.1dB/cm at 1550nm have been achieved in as deposited films

Improved method for hot embossing As 2 S 3 waveguides employing a thermally stable chalcogenide coating

We demonstrate the fabrication of As2S3 rib waveguides using hot embossing. Because of the high temperature required, a thin (50nm) Ge11.5As24Se64.5 was thermally evaporated on top of an 870nm As2S3 layer to protect against surface degradation during embossing. The waveguides propagation loss was 0.52dB/cm for the TE and 0.41dB/cm for the TM polarizations at 1550nm for a waveguide cross-section dimension of 3.8 × 1μm. The nonlinearity of a 2.2μm wide waveguide was shown to be 13500W-1km-1 using four-wave mixing demonstrating that these embossed waveguides were capable of being used for all-optical processing

Polarization-independent chalcogenide glass nanowires with anomalous dispersion for all-optical processing

We demonstrate the design and fabrication of square Ge11.5As24Se64.5 (Ge11) nonlinear nanowires fully embedded in a silica cladding for polarization independent (P-I) nonlinear processing. We observed similar performance for FWM using both TE and TM modes confirming that a near P-I operation was obtained. In addition we find that the supercontinuum spectrum that can be generated in the nanowires using 1ps pulse pulses with around 30W peak power was independent of polarization

The Impact of Thermal- and Photo-annealing of Chalcogenide Films for Optical Waveguides

We applied thermal- and band-edge light annealing on an as-deposited As2S3 film to mitigate its phase separation and, thus to improve the propagation losses of fabricated optical waveguides. Studies of the film micro structure revealed a difference between atomic bonds and linked phases among the as-deposited, thermally-annealed, and optically-annealed films. We fabricated rib-type waveguides with 4 micron width from 0.85 μm thick films, and measured the insertion losses. Around 0.4 and 0.2 dB/cm propagation losses were obtained in the waveguides produced from as-deposited and annealed films, respectively. The waveguides produced from photo-annealed film showed almost the same propagation losses to those from thermally-annealed material. Our results, however, indicate optical-annealing provides some advantages over thermal annealing for waveguide fabrication, such as the absence of film cracking which observed at high temperature processing