Study of resonator losses in Optically-pumped Perovskite lasers

Metal Halide Perovskite Semiconductors have been demonstrated in the last decade to be very promising materials for optoelectronic devices due to their tunable direct band gap nature. Perovskite light-emitting diodes (PeLEDs) have witnessed a remarkable success in the recent years, achieving external quantum efficiencies (EQE) of more than 20% and half-lifetimes > 100 h, bringing them closer to more mature thin-film devices based on organic semiconductors and core-shell quantum dots. Another interesting aspect of these materials is that they show signs of emitting stimulated emission when they are excited using external lasers. This property proves that these materials can be used to make lasers, and in fact, Optically pumped perovskite-based lasers have been demonstrated in literature too. In the ULTRA-LUX project, we aim to demonstrate a perovskite-based electrically pumped laser, a breakthrough that will lead to many applications such as on-chip light sources integrated into common CMOS photonic platforms, Lab-on-a-Chip devices, and advanced spectroscopy.

A laser consists of a gain medium and a resonator. There are several types of resonator topologies defined for conventional lasers and perovskite-based lasers (for example, Fabry-Perot cavity, Ring Resonator). An important aspect of laser design is to ensure that the overall gain of the laser overcomes the waveguide losses and mirror loss of the resonator. To achieve this, resonators need to be designed with as little parasitic mirror loss as possible.

The thesis would be split into the following steps:

1. Literature survey to study different resonator designs and loss mechanisms.
2. Modelling the resonator structures in software and predicting the mirror loss.
3. Using the model, the student should design resonators with an optimal trade-off of waveguide loss and resonator loss at a design wavelength.

The objectives and the approach can be tailored to the student’s interest and expertise. The student will benefit from the support of a multi-disciplinary collaborative team of PhD students, Postdocs, senior researchers, and Professors. The project is expected to help the student acquire different skills which are useful for further academic work or for the job market. If the results are beyond state of the art, this work has the potential to contribute to a high-quality scientific publication. 

The student is expected to be a self-driven and motivated individual, willing to tackle different tasks and learn new skills to achieve his objectives. The student should also be a team-player, be willing to communicate in meetings, and report on the progress regularly. Knowledge of semiconductor physics and laser physics is highly recommended.