Challenges in Orbital Angular Momentum

Stand in the way of a light beam and it could both knock you over and send you in a twirl. Over 100 years ago Maxwell worked out the fundamental equations describing how light propagates through space. Embedded within these equations is that light carries both energy and momentum, but although its energy is apparent in our everyday lives, its momentum is not. However, shine light down a microscope and its momentum can be seen to move, or trap, microscopic objects. Circularly polarized light also carries a Spin Angular Momentum causing the microscopic object to spin. Although the study of light has been central to the development of modern physics, it was not until the 1990's that it was realized that a whole new class of light beam could be created simply in the laboratory. Inserting a modified diffraction grating in the beam from a laser pointer is all that is required to create a light beam carrying Orbital Angular Momentum. The effect of OAM can be 100's time greater than that given by the spin alone - allowing our previous demonstration of the optical rotation of microscopic objects: an optical spanner! Beyond microscopic rotations, Orbital Angular Momentum (OAM) opens new opportunities across optical science.We wish to unlock the potential of OAM in both classical and quantum science. However, fundamental questions remain pertaining both to the underlying physics and technological limitations. This research programme will address these limitations, each a scientific achievement in their own right but together paving the route to:- OAM to enable an improved form of microscopy.- OAM as a secure basis on which to build a fast cryptographic network.- OAM at the heart of new types of optical sensors. We benefit from critical friends and will form an international steering panel to meet annually with the team. We have the agreement of two of the world's leading scientists to serve on this panel. To maximise our wider impact, the panel will also include an industrialist from Scottish Enterprise and be convened by the chair of the Glasgow University KT committee. The panel will agree with the PIs, quantitative targets for high-impact journal publications, invited talks at both academic and industrial events and, most importantly, targets for exploitation (patents, license, consultancy).

Communications and engagement With respect to our scientific peers, we will use the well-tested routes of engaging with beneficiaries via publications, conference presentations and reviews in wider-access publications. We will additionally establish a website to highlight and explain both the techniques and the results that can be obtained with OAM over a wide range of fields. We will also make various videos of our research available via our website and YouTube, which we have previously found useful for public and politicians alike! (See, for example, http://www.physics.gla.ac.uk/Optics/projects/tweezers/tweezers_movie.mov). With respect to the general public, many members of the extended grouping are leaders in Science Outreach. This occurs at formal and informal levels with Schools and Science Centres. Over the years both Barnett's and Padgett's groups have organised summers schools, targeted at secondary teachers (the next is planned for 2011), hosted school visits and delivered lectures/workshops at schools and public venues. The communication offices of the Universities of Glasgow and Strathclyde prepare press releases announcing significant advances in research by University Research Groups. They maintain good connections to the important scientific correspondents at the BBC and the broadsheets. Third party press coverage of our work typically amounts to scores of articles each year, featuring three or four different research results (for examples, see http://www.physics.gla.ac.uk/Optics/press). The benefit of running Open Days was established during our Basic Technology Dynamic Holographic Assembler project (collaboration with Bristol). These Open Days consisted of presentations and hands-on demonstrations of the technology to interested parties. In this way, we have been able to introduce a novel technique to previously unidentified beneficiaries, thereby increasing the value of the project. The regional development agency (i.e. Scottish Enterprise) has acted as a catalyst for new commercial connections supporting and promoting such events across its regional business. We will follow the same model for this programme, especially once our technology demonstrators are operational. Exploitation and Application Glasgow and Strathclyde Universities have excellent Enterprise divisions, thoroughly experienced in drafting, filing, managing and licensing patents originating from such projects. The Barnett and Padgett Groups have filed a number of patents, involving both their joint and individual work with various bodies, including industrial organisations. We also have experience of licensing our technology with the support of the enterprise team. For example, Padgett's group has had extensive experience in exactly this aspect of instrument design and construction. Examples include the design and manufacture of a Fourier-transform spectrometer for the detection of toxic gases; gas monitoring systems for monitoring volcanic gases; a bed-side monitor of exhaled ethane at the ppb level; a vehicle installed gas detection system for detection of oil and gas reserves; a fluorescent detection system for early stage skin cancers and, most recently, holographic optical tweezers installed and operational in a number of collaborating laboratories. We have collaborations with various possible end-users, both within Glasgow and further afield.