Pump-probe detuning dependence of four-wave mixing pulse in an SOA

Four-wave mixing (FWM) between 2-ps pulses in a multiquantum-well semiconductor optical amplifier (SOA) is presented. The conjugate pulses are fully characterized using the frequency-resolved optical gating technique. The detuning between the pump and probe is varied, leading to a compression of the FWM signal from 3.71 to 2.77 ps as the detuning is increased from 5 to 25 nm. The output conjugate pulse is always broader than the injected probe signal due to gain saturation effects. A reshaping of the conjugate pulse is also measured. However, large nonlinearities are introduced to the frequency chirp across the pulse for large detunings which may degrade the performance of four-wave-mixing-based all-optical processing applications in SOAs

The Psychological Effects of the Voice Change in Female Students and the Implications of Current Pedagogy

The voice change process is a treacherous time, and the female voice change process is underrepresented in literature and often ignored in classrooms (Sweet, 2018). The purpose of this study is to explore the psychological effects of the voice change process in female students and identify current pedagogical trends as used by current secondary choral music educators. Participants included a) Choral music education students who experienced a female voice change and b) Current secondary choral music educators. Choral music education students responded to a background survey which collected voice change process self-efficacy data. Selected informants underwent semi-structured interviews about their voice change experience. Current secondary choral music educators responded to an attitudinal/pedagogical survey of both Likert-type and open-ended prompts. An overarching theme for choral music education students included the aspects of typical adolescent psychological development. This includes perceptions of fear, a “violation of the ensemble” (Sweet, 2015), negative self-efficacy, the “imaginary audience” (Elkind, 1967), and the negative influence from family and teachers. Secondary choral music educators showed differences in levels of preparation and confidence with the female voice change. These findings are most likely directly related to the lack of Social Emotional Learning techniques in past and current classrooms. Applications of this study may continue to inform the field of music education of the effects of the female voice change and pedagogical changes that can be made to lessen negative psychological effects. Future researchers may focus on the effectiveness of pedagogical approaches in use by secondary choral music educators

Can the integration of BIM and GIS enhance information management for large scale linear infrastructure projects?

The integration of BIM and GIS is the subject of considerable research, particularly as the two coalesce for the purpose of information management. Large scale infrastructure projects require best practice in terms of how information is managed given the volume of information generated throughout the project lifecycle and the numerous parties requiring access to project content. This paper investigates whether the integration of BIM and GIS can enhance information management on large scale linear infrastructure projects. The research comprised a literature review and interviews with a number of BIM/GIS professionals actively working on linear infrastructure projects across the world. Some of the key findings to emerge from this research include the use of GIS web platforms to act as ‘gateways’ to project content, the importance of the CDE for information management, the use of ETL tools for moving data between BIM and GIS and finally the criticality of skilled personnel for ensuring the tools and workflows are applied correctly. The key findings resulted in a proposed implementation strategy for BIM-GIS integration for large scale linear infrastructure projects such as MetroLink. This research demonstrates that BIM and GIS complement each other when it comes to information management and the synergies between them strengthen the case for further integration

Pulse pedestal suppression using four-wave mixing in an SOA

Experimental results are presented demonstrating how four-wave mixing in a semiconductor optical amplifier can be used to remove pulse pedestals introduced due to nonlinearities which occur upon pulse propagation in an optical system. Such pedestals would degrade the performance of an optical time-division-multiplexed system due to coherent interaction between channels. An improvement of the temporal pulse suppression ratio to greater than 30 dB is achieved regardless of the level of the pulse pedestal on the input signal. This improvement takes place simultaneously with wavelength conversion and compression of the optical pulse

Numerical analysis of four-wave mixing between 2 ps mode-locked laser pulses in a tensile-strained bulk SOA

A numerical model of four-wave mixing between 2-ps pulses in a tensile-strained bulk semiconductor optical amplifier is presented. The model utilizes a modified Schrodinger equation to model the pulse propagation. The Schrodinger equation parameters such as the material gain first and second order dispersion, linewidth enhancement factors and optical loss coefficient are obtained using a previously developed steady-state model. The predicted four-wave mixing pulse characteristics show reasonably good agreement with experimental pulse characteristics obtained using frequency resolved optical gating

The ferroelectric phase of CdTiO3. A powder neutron diffraction study.

The synthesis of bulk samples of polycrystalline CdTiO3 in both the rhombohedral ilmenite and orthorhombic perovskite forms is described and the structures of these have been refined using powder neutron diffraction data. This involved the preparation of samples enriched in Cd-114. Cooling perovskite-type CdTiO3 to 4 K induces a ferroelectric phase transition, with the neutron data suggesting the low temperature structure is in Pna21. Mode analysis shows the polar mode to be dominant at low temperatures. The ilmenite-structure of CdTiO3 is compared with that of ZnTiO3. The refined scattering length of the Cd-114 is estimated to be 5.56 fm.Australian Research Counci