Here at the Ultrashort-Pulse Laser Research Group, we are involved with the generation, characterisation and application of ultrashort (picosecond and femtosecond) pulses from a wide variety of laser sources. Details of each project are outlined below.

Modular Ultrafast Sources for Intergrated control

Modular Ultrafast Sourses for Integrated Control (MUSIC) is a joint project which seeks to lead the way in the development of a new generation of ultrafast lasers. By adopting a modular approach for laser design we aim to demonstrate a platform from which lasers can be designed to address a wide range of user-specific requirements. Although vibronic crystals have been deployed widely in ultrashort-pulse lasers the flexibility offered by conventional laser designs is very limited. To remedy this situation we intend to revolutionise cavity design to enable electrical control of the laser output parameters. Progress is expected to lead to a new generation of lasers that can give applications compatibility that far exceeds that available from traditional laser system designs.

This project is being lead by Professor Wilson Sibbett here at the University of St Andrews. Other investigators include Dr Tom Brown (also at St Andrews) Professors Ian White and Richard Penty (Centre for Photonics Systems, University of Cambridge) Professor Martin Dawson FRSE, Dr Stephane Calvez and Dr David Burns (Institute of Photonics, University of Strathclyde). We have put together a research team having complementary expertise and established track records of international excellence in photonics. This project as a whole is managed from St Andrews University but all three research groups undertake interactive research on all aspects of laser development. Further information can be found at the dedicated MUSIC website.

In terms if the research effort taking place at St Andrews, Christopher Leburn, Klaus Metzger and Christine Crombie are the three main researchers working on this project. There research includes the following activites:

  • Novel SESAM devices for near-infrared femtosecond lasers

  • Phase managment of ultrafast sources

  • Remote controlled semiconductor lasers

    • Photon flow

    Photonics is the technology that underpins fibre-optic communications and could augment electronics in future optical and optical sensing devices for engineering applications. Making the leap from a society that uses silicon chips to one in which optical materials are at the heart of information technology, however, requires what this project's leader describes as a “seamless flow of photons” that overcomes the scattering and leakage problems caused by differences in refractive index and thermal mismatches when disparate materials are integrated.

    The researchers hope that being able to couple chemically dissimilar photonic materials, such as glass-based materials and inorganic semiconductors (rare-earth doped glass, III-V compound semiconductors, and polymers) will lead to novel devices for signal processing in telecommunications, analytical devices that use mid-infrared light for chemical and biological sensors, biophotonics and imaging. There will also be applications in space exploration, environment monitoring, data storage, security, and the military.

    The project is run from the University of Leeds by Professor Animesh Jha and also invloves collaborators from the University of Sheffield, The University of Cambridge, Heriot-Watt University and ourselves here at St Andrews. The W-Squad members who are involved in this project include, Prof. Wilson Sibbett, Dr Tom Brown, Dr Alex Lagatsky, Miss Foina Bain and Mr Flavio Fusari from the W-Squad group. The project has four main themes. The first is materials and integrated waveguide engineering, second optoelectronic pump sources, third, active components, and the fourth applications.

    Within materials engineering, the researchers will develop novel thin-film materials processing techniques for glass and polymers to make new types of integrated waveguides for active and passive device applications. New types of glasses offer numerous advantages over traditional silica and silicate materials for designing lasers, amplifiers, nonlinear and sensor devices. The first goal in the area of optoelectronic pumps will be to design structures based on III-V compound semiconductor technology for superluminescent light emitting diodes, diode lasers, and quantum dot structures for pumping light into glass waveguides for amplification and tuneable lasers operating in the ultraviolet-visible and near and midinfrared. The glass and semiconductor groups are also responsible for designing integration technology for creating monolithic designs for fabrication by addressing the issues relating to thermal and refractive index mismatches

    The Biophotonics Collaboration

    The University of St Andrews has established a strong multidisciplinary biomedical photonics collaboration between researchers in physics, biology, medicine, and chemistry. The core remit of the collaboration is to exploit novel emerging photonics techniques in the study and treatment of disease processes at the cellular and molecular levels. Craig McDougall and Tom Brown have been heavily involved in this collaborraton, particularly in the two following areas:

    Optical Transfection - Injecting Membrane Impermeable Substances into Single Cells

    The ability to load membrane impermeable substances into cells is of great interest to cell biologists.  Optical transfection is one of the few technologies that allows single cells to easily be transfected, without affecting neighbouring cells.  The image on the right shows six cells, three of which were transfected with a plasmid encoding for green fluorescent protein (green & blue cells), and three of which that were not.  Cells are co-stained with the blue nuclear dye, DAPI, so only the nuclei of untransfected cells are visible.   Early transfection work employed a Ti:Sapphire femtosecond pulsed laser using a standard Gaussian beam profile.  More recent work has employed the use of a Bessel Beam profile, obviating the need for exact focussing and opening the possibility of a “point-and-shoot” device for the biological community. 

    Caged Compounds - Developing Novel Caged Compounds and Light Sources to Uncage Them

    A caged compound remains biologically inactive until activated by light, typically by the photolysis of a protective group. In a collaboration between the Schools of Chemistry and Physics, caged compounds and laser sources to activate them are under development at St Andrews. One such caged compound is capsaicin, the molecule that gives chilli peppers their “heat.” The capsaicin receptor, called Transient Receptor Potential Channel–Vanilloid Subtype 1 (TRPV1), is an important potential therapeutic target in the treatment of pain. Caged capsaicin therefore allows high temporal and spatial control of the activation of the TRPV1 receptor. In contrast to activation by the traditional flashlamp method, laser irradiation allows the possibility of the separate activation of two caged compounds using different laser wavelengths.

    Araknes project

    ARAKNES (Array of Robots Augmenting the KiNematics of Ednoluminal Surgery) is a project that aims at bringing inside the patient’s stomach a set of advanced bio-robotic and microsystem technologies for therapy and surgery.

    The ultimate goal of ARAKNES is to integrate the advantages of traditional open surgery, laparoscopic surgery (MIS), and robotics surgery into a novel operative system for bi-manual, ambulatory, tethered, visible scarless surgery, based on an array of smart microrobotic instrumentation.

    Optical diagnostic techniques offer the possibility of non-intrusive objective diagnostics both in vitro and in vivo. Raman spectroscopy is a powerful laser-based technique which can provide biochemical fingerprints of the biological sample under investigation. It has the potential to diagnose tissue as being cancerous or non-cancerous, and hence could provide a surgeon with “on-the-fly” tissue diagnosis. Optical Coherence Tomography (OCT) technique allows high spatial resolution imaging at depth within tissue using optical radiation. It complements Raman spectroscopy nicely in its ability to provide morphological information about underlying tissue. Dr Mario Giardini and Dr Gajendra Singh are currently developing a combined Raman and OCT (ROCT) system which will aid in the characterisation of suspicious tissue within the GI tract and lead to real time disease diagnosis.

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