The effect of dielectric metamaterials on ultrashort laser pulses

Abstract

Dielectric metasurfaces are the state of the art of functional optical devices with light manipulating capabilities. Metasurfaces are planar devices which makes them highly efficient since they do not suffer from propagation effects. These devices consist of sub-wavelength dielectric structures arranged in a lattice, situated on a substrate of dielectric or metallic material. They have been shown to have the ability of local phase and polarization control. Furthermore, due to their design, they are a promising candidate to replace conventional refractive and diffractive optics as a more compact and versatile option. Their light manipulating capabilities stem from their sub-wavelengths structures which support Mie resonances. With these resonances, light can be locally confined in the metasurface, allowing for local control of light on a sub-wavelength scale. Many metasurfaces in research are considered for continuous wave sources, but in recent years, ultrafast physics has made advances with dielectric metasurfaces. As setups for pulse-shaping in ultrafast physics are large and suffer from losses, metasurfaces could be a functional alternative. In this thesis, the pulse-manipulating capabilities of dielectric metasurfaces are investigated. By solving Maxwell’s equations in the time domain, the response of dielectric metasurfaces are investigated when femtosecond pulses are incident on them. It was found that, by designing a metasurface that has resonances within the spectrum of the pulse, the metasurface exhibited pulse manipulating capabilities. Pulse-splitting, spectral filtering and temporal oscillations of the pulse envelope were found as properties of designed metasurfaces. This work defines a starting point for the design of dielectric metasurfaces for the manipulation of ultrashort laser pulses in the temporal and spectral domain.

Popular Abstract

Controlling light is critical to human advancement. It gives us a tool to investigate nature and is also important for information processing, sensing and manufacturing, to name a few. In the past decades, researches have investigated a new type of very thin material that can shape light, called metasurfaces. Usually, they are no thicker than a micrometer, that is about a 100 times thinner than a human hair. As chips in a computer are made with nanofabrication methods, metasurfaces can be produced with similar techniques, which mean that they can be readily produced with the equipment we have. But why do we need such methods to produce them?
The power of metasurfaces stems from their ability to confine light. Think of it like this: a window just let light go right through it in order for you to see what is outside. Metasurfaces do let light through, but not directly. Metasurfaces trap light, making it bounce around inside it in different directions before finally letting it out, they are said to support resonances. For researches, this is very interesting. By using these resonances, one can shape light to applicable forms. For example, light passing through a metasurface can be steered and focused in any direction. It might be interesting to shape any type of light, but for the purposes of my work, pulsed lasers is the choice.
Maybe not useful for the average person, but one special type of light is an ultrashort laser pulse. Laser pulses are what they sound like: laser light in the form of pulses. In order to get these pulses, a wide range of colours of light interact with each other, cancelling each other out everywhere except within the short pulse duration. Ultrashort laser pulses are extremely fast, meaning that the whole pulse can pass by an object in a very short time frame. How fast? Well, the pulses I am interested in pass objects in a matter of femtoseconds. A femtosecond is to a second as a second is to 31 million years!
Ultrafast laser pulses are both used in research and in technology, for example, in laser eye surgery. To have such pulses for a specific application, we want to be able to manipulate the pulses to any shape. This, we can already do with existing optical devices, but the search for more efficient ways is ongoing.
This is where metasurfaces come in, seemingly perfect for the job. They are efficient, versatile and very small. So the question is, can metasurfaces be useful for laser pulses? For shaping pulses, metasurfaces have been confirmed to be able to shape pulses. However, this has only been done by spatially separating the colours in a pulse and introducing one metasurface for each colour. In my project, I want to investigate to what extent a single metasurface can shape laser pulses. I do not do this in practice, but with simulations. In a simulation software, I can make a laser pulse pass through a metasurface and look at the results. What I found is that, indeed metasurfaces are able to shape pulses, and by shaping I mean split the pulse into two pulses or a chain of many smaller pulses.

• author: Elgbro, Daniel
• supervisor: Cord Arnold; Matias Kagias
• organization: Atomic Physics; Department of Physics
• course: PHYM03 20252
• year: 2026
• type: H2 - Master's Degree (Two Years)
• subject: Physics and Astronomy
• keywords: optics, metasurface, dielectric metasurface, ultrafast optics, ultrashort laserpulse, ultrafast metaphotonics, FDTD, pulse manipulation, pulse shaping, Mie resonance, photonics
• publication/series: Lund Reports in Atomic Physics (LRAP)
• report number: 621
• language: English
• id: 9222132
• date added to LUP: 2026-02-06 07:54:41
• date last changed: 2026-02-06 07:54:41