New doctors: María Duque Gijón and Mohammad Nayeem Akhter!

Dr. María Duque Gijón defended her thesis on 05/12/2024, co-tutored by Prof. Cristina Massoller and Dr. Jordi Tiana.

The thesis, titled "Experimental Study of the Coherence of Light Emitted by a Semiconductor Laser with Optical Feedback," investigates the emergence and evolution of coherence during the startup phase of a laser under different optical feedback conditions. It also examines the effects of sinusoidal modulation of the injection current on laser coherence and includes a study on the impact of optical injection. Semiconductor lasers are widely used in telecommunications, sensing, metrology, and biomedicine due to their compact size, efficiency, and versatility. This research employs a technique based on random intensity patterns (speckle) to analyze how optical feedback influences the temporal and spatial coherence of these lasers.

https://fisica.upc.edu/es/noticias/estudio-de-la-coherencia-de-un-laser-de-semiconductor-con-realimentacion-optica

On the other hand, Dr. Mohammad Nayeem Akhter defended his thesis on 23/12/2024, co-tutored by Prof. Kestutis Staliunas and Dr. Muriel Botey.

His thesis, titled "Non-Hermitian Mode Management in Optical Fibers and Waveguides," introduces an innovative method for beam transformation in graded-index multimode fibers (GRIN MMFs) using non-Hermitian mode control. MMFs are increasingly relevant in optical communications, high-power lasers, optical sensing, and imaging. However, their complex spatiotemporal dynamics often lead to multimode beam evolution, causing speckle and reduced beam quality. His research demonstrates how non-Hermitian mode management can effectively control beam propagation in MMFs, addressing challenges that conventional techniques—such as index modulation, scattering, and nonlinear interactions—fail to overcome.

https://fisica.upc.edu/es/noticias/gestion-de-modos-no-hermiticos-en-fibras-opticas-y-guias-de-onda