PhD position in Polychromatic optical singularities at King's College London, UK

Starting from the early 1990s, a quiet revolution has been taking place in optics, coming from a growing realization that one can get a huge amount of information about the propagation of a beam of light by understanding the nature and position of the optical singularities in the beam. Optical singularities are places where one or more properties of light become undefined, with the core example being optical phase vortices: places in the beam where the amplitude vanishes, the phase becomes undefined, and the wavefronts twist in a helical pattern. These vortices can carry angular momentum, and, together with vector singularities that involve the polarization of light, they have revolutionized optics from microscopy and lithography to our fundamental understanding of light [1].

One key discovery of recent years is the wealth of structures that becomes possible if one allows light to become polychromatic – that is, the optical singularities of multi-colour light fields. By borrowing techniques and perspectives from the field of attosecond science [2], it has recently been possible to find new topologies and symmetries of light [3], new forms of angular momentum [3], completely new physical quantities in light [4], and novel types of optical chirality [5].

Your project will explore this fresh new area of research, looking for new types of optical singularities in bichromatic and polychromatic light. You will identify configurations of interest, analyze the electromagnetic field, and construct novel tools for analysis, building on previous work on nonlinear tensor moments of the field. You will analyze the geometry of the optical singularities, and their relationship with physical quantities such as spin and orbital angular momenta. The end goal is a substantive leap forward in our ability to understand polychromatic structured light, in the number and variety of known polychromatic optical singularities, and in our understanding of their significance and applications.

The project will take place within the Photonics & Nanotechnology group at KCL, in close collaboration with the attosecond-science team within P&N. You will collaborate with the attosecond science team to design applications of your discoveries to high-harmonic generation, and with nanoplasmonics researchers in P&N to identify possible realizations and applications in nonlinear plasmonics.

The activities involved in the project will include:

• Theoretical analysis, using analytical and numerical methods, of structured light and optical singularities.
• Design of novel tools and constructions to analyse electromagnetic fields, and discovery of their possible singularities.
• Development and optimization of software for numerical calculations.
• Collaboration with experimental groups to propose new experiments and analyze existing data.
• Attendance of conferences, workshops and summer schools.

Candidate requirements:

Candidates will be judged according to how well they meet the following criteria:

• A passion for research, and a desire to learn new skills
• Creativity and a collaborative spirit; the ability to work in a team
• Fluency with analytical methods of theoretical physics and ability to apply mathematical skills to analyze and solve problems
• Ability to formulate and test hypotheses and to generate and analyze numerical data
• Ability to effectively communicate research findings
• A background in optics, quantum mechanics, or light-matter interaction
• A first-class honours degree to second class honours upper division (2.1) in Physics, Mathematics, or related subjects
• The ability to clearly communicate your ideas to your colleagues and to people beyond our research team (please note that there are formal requirements on English language qualifications, which are detailed in https://www.kcl.ac.uk/study/postgraduate/apply/entry-requirements/english-language.aspx (Band D))

The following skills are desirable but not essential:

• An interdisciplinary degree, or experience outside of main degree topic
• Experience with working in a research environment
• Basic knowledge of structured light, including phase- and vector-vortex beams as well as other types of polarization structuring
• Basic knowledge of nonlinear optics, including strong-field physics and high-harmonic generation
• Knowledge of Wolfram Mathematica or other computer algebra systems
• Ability to program in one or more programming language, such as Wolfram Language, python, Julia, C++, etc.

Application Deadline: 1 May 2024, noon

For informal enquiries and to discuss the scope of the project, please contact Emilio Pisanty (emilio.pisanty@kcl.ac.uk).

More information >>

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References
1. K.Y. Bliokh et al. Roadmap on structured waves. J. Opt. 25, 103001 (2023). arXiv: 2301.05349.
2. D. Villeneuve. Attosecond Science. Contemp. Phys. 59, 47 (2018). JASLab eprint.
3. E. Pisanty et al. Knotting fractional-order knots with the polarization state of light. Nat. Photon. 13, 569 (2019). arXiv:1808.05193.
4. L. Rego et al. Generation of extreme-ultraviolet beams with time-varying orbital angular momentum. Science 364, eaaw9486 (2019). arXiv:1901.10942.
5. N. Mayer et al. Chiral topological light for detecting robust enantio-sensitive observables. arXiv:2303.10932 (2023).