The University of Southampton

Multimode Photonics Group

Led by Dr. Massimiliano Guasoni, the Multimode Photonics Group focuses on the design and fabrication of optical waveguides where strong interactions between different spatial modes take place. The exploitation of these interactions paves the way towards exceptional opportunities and novel functionalities well beyond those available in traditional optical devices.

Research impact

Optical waveguides are physical structures that guide light. Optical fibers, which are the backbone of the modern Internet network, represent a popular and relevant example of waveguide.

Light can propagate into a waveguide in the form of different beams, each one characterized by a specific spatial shape (see figure below). These beams are called spatial modes.

Despite the existence of an infinity of different modes, however current technology is mainly based on the exploitation of just one spatial mode, which is the mode with circular shape. This is the case, for example, of the light travelling in optical fibers or emitted from a laser pointer (see below).  Nevertheless, in recent years a new paradigm has emerged in optics, which is the exploration of several modes beyond the circular-shaped one (so called higher-order modes).

When several different modes are confined into a waveguide, they can strongly interact via the nonlinear response of the waveguide material. In this way, photons from a given mode at some frequency can be converted into a new mode at a different frequency. It becomes therefore possible to generate light in a very broad spectral region inaccessible so far and, at the same time, to control the spatial profile of light, which allows the generation of beams with many different shapes.

A precise design of the waveguide material and geometry is of utmost importance to maximize the frequency conversion. The design and fabrication of optimal waveguides is the main objective of our work. Different kind of waveguides are explored. From long optical fibers, where the frequency conversion can be exploited to develop broadband optical amplifiers to speed up the Internet network, up to tiny on-chip waveguides, where different modal interactions can be exploited to generate light in a very broad infrared spectrum, which finds application in medicine, sensing and security.

Research facilities

Our research focuses on the design and fabrication of innovative optical waveguides. Both tasks are accomplished through the exploitation of world-class facilities available at the ORC.

The IRIDIS supercomputer, one of the most powerful in UK, allows running the heavy and complex numerical simulations required at the design stage.

For the fabrication and characterization of optical fibers and on-chip waveguides we have access to fiber-drawing towers, a dedicated centre for nanofabrication (including e-beam and optical lithography, chemical vapour deposition, sputterers, evaporators) and a wide range of optical sources (high-power fiber lasers and laser diodes, optical parametric oscillators, supercontinuum sources).


Our group works in close collaboration with several research groups, both within the ORC and worldwide.

Internal collaborations (ORC groups):

Advanced Fibre Technologies & Applications

Nonlinear Semiconductor Photonics

Silicon Photonics

Computational Nonlinear Optics

External academic collaborations

  • Pr. C.De Angelis, University of Brescia, Italy.
  • Pr. S.Wabnitz, University La Sapienza of Roma, Italy.
  • Pr. Y.Kivshar and Pr. D.Neshev, Australian National University, Australia.
  • Pr. G.Millot, Pr. A.Picozzi and Dr. J. Fatome, University of Bourgogne, France.  

External industrial collaborations

  • Huawei Technologies Co. 


All PhD projects:

  • Entry requirements: A very good undergraduate degree (at least a UK 2:1 honours degree, or its international equivalent). 
  • Closing date: Applications are accepted throughout the year and several start dates throughout the year are possible. Applications for the typical Sept./Oct. 2023 start should be received no later than 31 August 2023. 
  • Funding: For UK students, Tuition Fees and a stipend of £20,000 tax-free per annum for up to 3.5 years. For international students, the ORC offers a small number of scholarships to outstanding applicants and students with funding are also encouraged to apply.
  • Apply online here


Current projects

Next Generation Miniaturized Optical Sources 

Supervisory team: Massimiliano Guasoni (supervisor), Cosimo Lacava (co-supervisor)

This PhD project aims to open new frontiers in nanophotonics by designing and fabricating a new class of miniaturized optical sources. These sources will allow light emission in a broad frequency spectrum well beyond what is possible with current lasers.  These sources will find application in several fields: from medicine, as primary components of non-invasive breath analysers for cancer diagnosis; to security, both for the detection of explosives and for the development of efficient anti-missile systems in civil aircrafts; up to environment, for the monitoring of air pollution and green energy generation. Join us to pioneer the next generation miniaturized optical sources! 


Shaping light at the nanoscale with dielectric nanoantennas

Supervisory team: Massimiliano Guasoni, Cosimo Lacava (co-supervisor)

In the last decade, nanophotonics has emerged as one of the most important research fields in optics. A tiny nano-object plays the role of a nanoantenna: when excited by a light source, it scatters light in the surrounding environment in one or more directions that depend on its geometry and material. An important issue that has not been fully understood yet is how to control the directionality and power of this scattered radiation.

The scope of this PhD project is to advance our knowledge in nanophotonics by designing and fabricating nanoantennas that allow full control of the scattered field at the nanoscale. Single nanoantennas with arbitrary shape as well as arrays of coupled nanoantennas will be designed, fabricated and tested.


Multimode fibre lasers 

Supervisory team: Massimiliano Guasoni, Lin Xu, David Richardson

Multimode optical fibres have recently emerged as a promising breakthrough technology to boost the data transmission speed of the Internet network to unprecedented levels. In these fibres each spatial mode carries an independent data channel, and the interaction (cross-talk) among different modes is a problem to avoid.

In this PhD project we want to reverse this point of view, looking for novel opportunities arising from the interaction among spatial modes. We will develop novel fibre lasers where this interaction is the keystone to achieve light generation over a wide spectral bandwidth, well beyond what is possible with current fibre laser technology.


Wideband fiber optical parametric amplifiers for Space Division Multiplexing technology

Supervisory Team: Massimiliano Guasoni, Lin Xu, David Richardson

Space Division Multiplexing (SDM) has recently emerged as a promising breakthrough technology to boost the data transmission speed of the Internet network to unprecedented levels. In SDM each spatial mode of an optical fiber carries an independent data channel, so that exploiting for example 10 modes can increase the data transmission speed up to 10 times. However, in order to move from a pure academic research to a fully exploitable commercial technology, SDM requires the development of novel devices that must be urgently addressed. The most important are multimode optical amplifiers, capable of amplifying simultaneously several different spatial modes. We aim at developing a novel idea of fiber optical multimode parametric amplification where four-wave-mixing between different fiber modes is exploited to amplify several modes in a wide bandwidth covering the main telecom windows (C+L bands). This is done through the design of novel optical fibers having special refractive-index profile.


Work with us

Please contact Dr. Massimiliano Guasoni ( for more details.


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