Random laser with III-V semiconductor nanowires

Semiconductor lasers are used extensively in our life for example optical telecommunications, bar code readers, CD players and the camera systems in mobile devices. Beside commercial applications, the well-established semiconductor theory and advanced fabrication technologies provide an excellent platform to study dynamic effect in chaotic random lasers. Recently, the main supervisor and his collaborators in Yale University and Imperial College London showed that the stability of semiconductor lasers can be improved by adopting chaotic cavity or randomising the refractive index of the cavity [1]. The suppressed instabilities using a chaotic or random cavity requires further theoretical studies for a complete understanding of the mechanism. However, it is a challenging task because multiple nonlinear effects should be considered and the numerical simulation processes can be heavily loaded due to complex material gain. Therefore, it is vital to develop an appropriate numerical model to predict the dynamic gain effect for complete understanding and new applications.
In this project, the student will be working on both theoretical modelling and experimental demonstration. In theoretical study, the student will model nonlinear effects (spatial hole burning, lens effect) in optical cavities and dielectric rod arrays and design an III-V nanowire array laser with a randomly perturbed lattice. This will be done via analytical approach and numerical methods such as the coupled mode theory, finite-difference time-domain model and finite-element method. In the experimental demonstration, the student will fabricate III-V semiconductor nanowire array using selective area epitaxy with MOVPE equipment in Ser Cymru group. The fabricated lasers will be characterised using the micro photoluminescent setup. This project can be successfully completed in 3.5 years (0.5 year: literature review, study on semiconductor laser physics, 1.5 year: simulation on nonlinear effect and design of laser, 2 years (0.5 year overlap): sample fabrication and characterisation).

1. Stefan Bittner, Stefano Guazzotti, Yongquan Zeng, Xiaonan Hu, Hasan Yılmaz, Kyungduk Kim, Sang Soon Oh, Qi Jie Wang, Ortwin Hess, Hui Cao, “Suppressing spatiotemporal lasing instabilities with wave-chaotic microcavities,” Science, 361 (9), 1225, 2018.