January 2012 - A spectral lens for light |
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As reported soon in Physical Review Letters, we have constructed a spectral lens, that is, a nanostructure that can either expand (“magnify”) or compress (“demagnify”) the spectrum of light (see figure). This lens could find application in spectroscopy (to improve the resolution of spectrometers) or in optical data transfer (to reduce the bandwidth of a signal).
For spectral compression, we raise the frequency of light, but we ensure that lower frequency components undergo a larger frequency shift than the higher frequencies (see figure). A photonic-crystal waveguide separates the frequencies for us: the higher frequencies are concentrated in the center of the waveguide whereas the lower frequencies spread out into the surrounding photonic crystal. Our spectral lens consists of such a waveguide in combination with a shadow mask. By hitting it with an intense laser pulse (“pump” in figure), the lower frequencies are shifted more as the mask protects the waveguide center. In this way, we have compressed the spectrum of an ultrashort test pulse by 12%. Much higher compression is possible by optimizing the parameters of the structure.
Figure: (a) Schematic of adiabatic light control.
(b) Experimental realization.
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October 2011 - Four of our researchers are selected to attend the "JSPS International School on Si Photonics 2011" to be held in Kyoto, Japan |
Four members of the group, Sebastian Schulz, Christian Reimer, Isabella Rey and Abdul Shakoor have been selected to attend the "JSPS International Schooling on Si Photoincs 2011" to be held in Kyoto, Japan between November 16-19, 2011. They have each also been awarded a full scholarship to cover all costs of their participation. |
September 2011 - Eight of our research team participate in "Group IV Photoncs 2011" held in London |
Eight of our research team submit and are accepted to participate in "Group IV Photonics 2011" being held at the Royal Society, London. Both Andrea and Isabella were invited to present papers which were greatly received (Andrea even managed to squeeze in 3 "final" slides). Two of our researchers, Isabella and Abdul, were also selected to receive the MPAGs student scholarship - which covers all conferece fees. |
June 2011 - Sebastian's paper "Understanding losses in photonic crystal waveguides" wins "Best student paper" at the Advanced Photonics Congress |
Sebastian wins "Best Student Paper" at the Advanced Photonics Congress, held by the Optical Society of America (OSA) in Toronto, Canada. The US$ 1000 award recognised Sebastian's paper "Understanding losses in photonic crystal waveguides" both for scientific merit and excellence of delivery.
His paper's abstract: Engineering dispersion and loss in photonic crystal
waveguides allows us to control propagation up to moderate group indices. Novel results on ‘over-engineered’ waveguides give insights into loss vs. both propagation constant and group index.
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April 2011 - "Slow-light and evanescent modes at interfaces in photonic crystal waveguides: optimal extraction from experimental near-field measurements" |
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Spotlight summary published in the Highlighted articles from OSA Journals section of Optics InfoBase (for more information see our publications section).
Figure: Dispersion for the slow-light waveguide with p2 = 0.4d |
Annett Klemm |
The group welcome Annett Klemm who re-joins the group after successfully completing her Erasmus Mundus Masters Degree, she now begins her PhD work investigating fast tunable optical filters for implementation within the PROPHET collaboration. |
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February 2011 - "The Slow-Light Race Is On" |
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Feature article published in Photonics Spectra (for more information see our publications section).
Figure: Schematic of slow-light propagation of pulses in a photonic crystal waveguide. Energy density of pulses in the slow mode is increased and, along with distributed feedback effects, enhances interactions with the material of the photonic crystal waveguide. (Inset) Scanning electron microscopy micrograph of a nanowire coupled to a silicon photonic crystal waveguide. Courtesy of the University of Sydney. |
December 2010 - "Low-power continuous-wave generation of visible
harmonics in silicon photonic crystal nanocavities
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Spotlight summary published in the Highlighted articles from OSA Journals section of Optics InfoBase (for more information see our publications section).
Figure: Sketch of the Second- and Third-Harmonic Generated emission from the Photonic Crystal cavity. |
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November 2010 - Andrea hits the headlines. |
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Andrea hit the headlines this month, with his latest piece of research on meta-materials. Using tiny atoms that can interact with light, Andrea has developed a flexible new 'smart' material that could theoretically appear invisible to the naked eye.
To read the relevant paper click here.
Figure: The Scotsman went one further by imagining Harry Potter as an undergraduate in St Salvator's Quadrangle wearing an invisibility gown!
Graphic Credit: Clive O'Neill, The Scotsman
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November 2010 - "Slotted Photonic Crystal Devices: Slow Light and Applications" becomes the most downloaded Slow and Fast Light Meeting paper |
Andrea's, Will's and Thomas' paper entitled "Slotted Photonic Crystal Devices: Slow Light and Applications" becomes the most downloaded Slow and Fast Light Meeting InfoBase Paper.
Figure: SEM image of a heterostructure Slotted Photonic Crystal (SPhC) cavity. The compressed region is highlighted in false colour (blue). |
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Marcello Ferrera |
The group welcome Marcello Ferrera who begins a Post-Doctoral position investigating waveguide and photonic crystal fabrication and characterisation in Silicon Nitride. |
July 2010 - "Planar photonic crystal cavities with far-field optimization for high coupling efficiency and quality factor" |
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Spotlight summary published in the Highlighted articles from OSA Journals section of Optics InfoBase (for more information see our publications section).
Figure: Schematic of far-field optimized PPhC cavity of the L3-type. Holes with red
edge are shrunk and shifted to optimize the Q-factor. Dark holes are modified to increase
the vertical out-coupling. |
June 2010 - "Adiabatic frequency conversion for optical data transfer" |
Lead article published in the Optoelectronics & Optical Communications section of the SPIE newsroom. Click here to view the article (Link to permanent publishers page available here).
Figure: Illustration of the frequency conversion scheme. (a) The signal pulse is launched into the ‘W1’ photonic crystal waveguide, where it is acted upon by an ultrafast (100fs) pump pulse. The signal is blueshifted before being output. (b) The mode spectrum of the waveguide as a function of time. The signal pulse is launched into the slow-light modes of the unperturbed waveguide, and the arrival of the pump-pulse blue-shifts the eigenfrequencies of these modes. |
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Paolo Cardile |
The Group welcome Paolo Cardile who is a visiting PhD student from Catania, Italy. He joins the group to work on the LECSIN project, with the ultimate goal of achieving laser emission by Er ions in an SOI-based photonic crystal cavity. |
Abdul Shakoor |
The group welcome Abdul Shakoor, who re-joins the group after completeing his Masters degree. Abdul now begins his PhD work on Silicon based Photonic Crystal Lasers. |
January 2010 - "But wait - there's more...! |
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Article published in Photonics Spectra
(L. Savage (Features editor), "But wait - there's more ... !", Photonics Spectra, January 2010, pp. 81-85)
Figure: Illustration of a slow-light optical buffer. At the entrance, the header is switched out and travels (fast) in the lower branch; meanwhile, the "payload" is stored in the buffer until the header is recognised. This combines the optical signal processing and buffering functions. Both the switch and the buffer are electically tunable. |
November 2009 - Away Day in Ballater, Aberdeenshire |
Our Away Day venue this year was the Hilton Craigdarroch, Ballater. While away we stayed at the Invercauld Lodges, taking over the entire complex of seven lodges.
The program, talks and photographs are available from the members login page.
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Tim James |
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The Group welcome Tim James who begins a Post Doctoral position looking at the Biophotonics area, primarily focussed on the development of monolithically integrated LED based fluorescence detection systems.
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Juntao Li |
The Group welcome Juntao Li who begins a Post Doctoral position focussing on the development of all-optical signal regeneration in slow light silicon photonic crystal waveguides.
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Kapil Debnath |
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The Group welcome Kapil Debnath who begins his PhD investigating CMOS integration with silicon photonic crystals
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Mark Scullion |
The Group welcome Mark Scullion who begins his PhD looking at slotted photonic crystal waveguides for use in a variety of applications.
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Perumal wins best thesis prize |
At the summer school for the Erasmus Mundus Master in Photonics class held in Ghent between June 22 - July 1st, Ulagalandha Perumal Dharanipathy ("Peru" to his friends) was awarded the prize for the best thesis project. This is a well deserved reward, given that Peru showed brilliance, great initiative, experimental and organisational skills in completing a project that combined slotted photonic crystal waveguides, biochemical functionalisation and in-depth discussions about possible applications in sea mammals research. |
Chris gets ponded after successfully completing his PhD |
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Green Light from Silicon |
Slow light has attracted significant interest recently as a potential
solution for optical delay lines and time-domain optical
signal processing1,2. Perhaps even more significant is the possibility
of dramatically enhancing nonlinear optical effects3,4 due
to the spatial compression of optical nergy5–7. Two-dimensional
silicon photonic-crystal waveguides have proven to be a
powerful platform for realizing slow light, being compatible
with on-chip integration and offering wide-bandwidth and dispersion-
free propagation2. Here, we report the slow-light
enhancement of a nonlinear optical process in a two-dimensional
silicon photonic-crystal waveguide. We observe visible
third-harmonic-generation at a wavelength of 520 nm with
only a few watts of peak power, and demonstrate strong
third-harmonic-generation enhancement due to the reduced
group velocity of the near-infrared pump signal. This demonstrates
yet another unexpected nonlinear function realized in
a CMOS-compatible silicon waveguide. |
| University press release |
Nature Photonics: Green Light from Silicon
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| Times Higher Education" -features Green Light for Silicon |
Armando Ricciardi |
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Armando Ricciardi joins the group this month with a focus on developing a tunable optical filter based on nanostructured MEMS mirrors. |
Isabella Rey |
The Microphotonics and Photonic Crystals Group welcomes Isabella Rey to St Andrews to commence her PhD. Isabella spent six months in the group last year. |
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September 2008 - Away Day in Glenshee |
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Our Away Day venue this year was Gulabin Lodge, Spittal of Glenshee which is on the Perthsire/Aberdeenshire border, situated at the foot of Ben Gulabin.
The program, talks and photographs are available from the members login page.
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