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Parity-time symmetric chain resonators (2016)
Conference Proceeding
Phang, S., Vukovic, A., Creagh, S., Gradoni, G., Sewell, P., & Benson, T. M. (2016). Parity-time symmetric chain resonators.

A simple tight-binding model to study the band-structure of an infinite length Parity-time (PT) symmetric chain of resonators is presented in this paper. In the talk, we will investigate the impact of having a structure of finite length and consider... Read More about Parity-time symmetric chain resonators.

Localized single frequency lasing states in a finite parity-time symmetric resonator chain (2016)
Journal Article
Phang, S., Vukovic, A., Creagh, S. C., Sewell, P., Gradoni, G., & Benson, T. M. (2016). Localized single frequency lasing states in a finite parity-time symmetric resonator chain. Scientific Reports, 6, Article e20499. https://doi.org/10.1038/srep20499

In this paper a practical case of a finite periodic Parity Time chain made of resonant dielectric cylinders is considered. The paper analyzes a more general case where PT symmetry is achieved by modulating both the real and imaginary part of the mate... Read More about Localized single frequency lasing states in a finite parity-time symmetric resonator chain.

A phase-space approach for propagating field–field correlation functions (2015)
Journal Article
Gradoni, G., Creagh, S. C., Tanner, G., Smartt, C., & Thomas, D. W. (2015). A phase-space approach for propagating field–field correlation functions. New Journal of Physics, 17, Article 093027. https://doi.org/10.1088/1367-2630/17/9/093027

We show that radiation from complex and inherently random but correlated wave sources can be modelled efficiently by using an approach based on the Wigner distribution function. Our method exploits the connection between correlation functions and the... Read More about A phase-space approach for propagating field–field correlation functions.

Threshold manipulation in parity-time symmetric microresonator chain (2015)
Conference Proceeding
Phang, S., Vukovic, A., Creagh, S., Benson, T. M., Gradoni, G., & Sewell, P. D. (2015). Threshold manipulation in parity-time symmetric microresonator chain.

This paper analyses the eigenfrequencies of an infinitely long chain of microresonators with PT symmetry. The results show that the depth of modulation of the real part of the refractive index can be used to control the threshold point of the PT stru... Read More about Threshold manipulation in parity-time symmetric microresonator chain.

Parity-time chain of whispering-gallery mode resonators (2015)
Conference Proceeding
Phang, S., Vukovic, A., Creagh, S., Benson, T. M., Gradoni, G., & Sewell, P. D. (2015). Parity-time chain of whispering-gallery mode resonators.

The paper analyses the dispersion characteristics of an infinitely long PT chain made of whispering gallery resonators with gain/loss modulation. The results show that the appearance of the threshold breaking point depends not only on both of couplin... Read More about Parity-time chain of whispering-gallery mode resonators.

Parity-time symmetric coupled microresonators with a dispersive gain/loss (2015)
Journal Article
Phang, S., Vukovic, A., Creagh, S. C., Benson, T. M., Sewell, P. D., & Gradoni, G. (2015). Parity-time symmetric coupled microresonators with a dispersive gain/loss. Optics Express, 23(9), 11493-11507. https://doi.org/10.1364/oe.23.011493

The paper reports on the coupling of Parity-Time (PT)-symmetric whispering gallery resonators with realistic material and gain/loss models. Response of the PT system is analyzed for the case of low and high material and gain dispersion, and also for... Read More about Parity-time symmetric coupled microresonators with a dispersive gain/loss.

Saturable and dispersive parity-time symmetric directional coupler: a transmission-line modelling study (2014)
Conference Proceeding
Phang, S., Vukovic, A., Benson, T. M., Creagh, S., Sewell, P., & Gradoni, G. (2014). Saturable and dispersive parity-time symmetric directional coupler: a transmission-line modelling study.

In this paper, numerical modelling of Parity-Time (PT) coupled waveguides is reported. The PT coupled waveguide structure consists of two coupled slab waveguides based on GaAs material with gain/loss material parameter models, including both dispersi... Read More about Saturable and dispersive parity-time symmetric directional coupler: a transmission-line modelling study.

In–out decomposition of boundary integral equations (2013)
Journal Article
Creagh, S. C., Hamdin, H. B., & Tanner, G. (2013). In–out decomposition of boundary integral equations. Journal of Physics A: Mathematical and Theoretical, 46(43), Article 435203. https://doi.org/10.1088/1751-8113/46/43/435203

We propose a reformulation of the boundary integral equations for the Helmholtz equation in a domain in terms of incoming and outgoing boundary waves. We obtain transfer operator descriptions which are exact and thus incorporate features such as diff... Read More about In–out decomposition of boundary integral equations.

Voltage and current spectra for matrix power converters (2009)
Journal Article
Cox, S. M., & Creagh, S. C. (2009). Voltage and current spectra for matrix power converters. SIAM Journal on Applied Mathematics, 69(5), https://doi.org/10.1137/080718863

Matrix power converters are used for transforming one alternating-current power supply to another, with different peak voltage and frequency. There are three input lines, with sinusoidally varying voltages which are 120? out of phase one from another... Read More about Voltage and current spectra for matrix power converters.

Coupled parity-time symmetric cavities: results from transmission line modelling simulations
Conference Proceeding
Phang, S., Vukovic, A., Creagh, S., Sewell, P. D., Gradoni, G., & Benson, T. M. (2015). Coupled parity-time symmetric cavities: results from transmission line modelling simulations.

This paper studies the impact of a dispersive gain/loss material model on Parity-Time (PT) coupled microresonator cavity structures using the time-domain Transmission-Line Modelling method. A modal analysis is also performed to compare the modal comp... Read More about Coupled parity-time symmetric cavities: results from transmission line modelling simulations.

Threshold preservation of PT-resonant structures in realistic-dispersive medium
Conference Proceeding
Phang, S., Vukovic, A., Creagh, S. C., Benson, T. M., Sewell, P., & Gradoni, G. Threshold preservation of PT-resonant structures in realistic-dispersive medium.

The impact of material dispersion in the performance of parity-time (PT) symmetric coupled microresonators is studied. The eigenfrequencies of the coupled PT-system are analysed for different dispersion parameter. We show that realistic dispersion pr... Read More about Threshold preservation of PT-resonant structures in realistic-dispersive medium.

Parity-Time coupled microresonators: Kramers-Kronig limitation
Conference Proceeding
Phang, S., Vukovic, A., Creagh, S. C., Sewell, P., Gradoni, G., & Benson, T. M. Parity-Time coupled microresonators: Kramers-Kronig limitation.

In this talk, we use a KKE argument to show that the presence of dispersion alters the eigen-frequencies of coupled PT coupled microresonators, so that their eigen-frequencies are no longer complex conjugates after the EP.