Nonlinear Photonics
The research covers several aspects of ‘Nonlinear Photonics’ with fundamental and applicative aspects, in particular the understanding of the complex nonlinear processes determining (and partially limiting) the performance of semiconductor-based photonic devices and lasers, their control and the utilization of nonlinearities for applications. Focus is on understanding and controlling the highly nonlinear dynamics of semiconductor lasers, especially VCSELs. On the fundamental side many activities have strong interdisciplinary aspects being connected to self-organization phenomena in nonequilibrium system ubiquitous in Nonlinear and Complexity Science, technology and nature. It is performed in close cooperation with the Computational Nonlinear Optics and Quantum Optics Group within the Optics Division.
Former projects
Vertical-cavity surface-emitting lasers (VCSELs) are a rather new type of semiconductor laser diode, in which – in contrast to conventional edge emitters – the direction of the light emission is parallel to the epitaxial growth direction. We study the connection between the carrier spin and the polarization of the emitted light of VCSELs.
Light does not stay confined to small regions in space or time, but wave packets of light have the natural tendency to broaden. For technical applications, it is important to counteract this natural tendency and to confine light to the smallest possible dimensions. Though great partial success was achieved by linear optical element as optical fibres, it was always the dream of researchers to confine light by self-action. This is why the concept of solitary waves received a lot of attraction during the last decades.
Semiconductor quantum dots are an exciting new material for photonics and quantum information because their properties can be tailored to a wide extent. In a first approximation, they can be considered as artificial atoms which strongly interact with their environment. This provides challenges as well as opportunities.
The band within the electromagnetic spectrum between about 300 GHz and 3 THz is often referred to as terahertz radiation. Terahertz radiation is considered to be an upcoming technology in material inspection, quality control, gas sensing, surveillance and security applications, and wireless, short-haul communication. We study a method to produce THz radiation by mixing two cw infrared lasers in a special kind of semiconductor (low-temperature grown GaAs).
We study nonlinear effects due to optical pumping using hot sodium vapour. Beside technical advantages, such as high optical quality, easy variation of parameters over a broad range, high resonant nonlinearity, the benefit of using an atomic vapour is that the equations governing the light-matter interaction can be derived directly from quantum mechanics via the density matrix approach.
Latest News
Observation of self-organized hexagons via optomechanically nonlinearities.
Observation of self-organized hexagons via optomechanically nonlinearities reported in Nature Photonics.
Invited symposium talk at PQE
GR. M. Robb: Invited symposium talk at PQE - 44th Winter Colloquium on the Physics of Quantum Electronic (Jan 2014).
Kinetic Theory for Transverse Optomechanical Instabilities
T. Ackemann hand an invited talk at the Sixth ‘Rio de la Plata’ Workshop on Lasers Dynamics and Nonlinear Photonics (Dec 2013).
Kinetic Theory for Transverse Optomechanical Instabilities
“Kinetic Theory for Transverse Optomechanical Instabilities” published in Physical Review Letters.
W. J. Firth had an invited talk at ENOS 13
W. J. Firth had an invited talk at ENOS 13 – Extreme Nonlinear Optics & Solitons (Oct 2013).
Recent publications
Coupling of magnetic and optomechanical structuring in cold atoms.
Physical Review A
105,
063508
(2022).
Dynamics of optomechanical droplets in a Bose-Einstein condensate.
Physical Review A
105,
063305
(2022).
Ground-state coherence versus orientation: Competing mechanisms for light-induced magnetic self-organization in cold atoms.
Physical Review A
105,
023505
(2022).
Rotating and spiraling spatial dissipative solitons of light and cold atoms.
Physical Review A
105,
023318
(2022).