Hybrid integrated narrow-linewidth laser at 488 nm via self-injection locking

Photonic integrated circuits (PICs) operating at blue wavelengths hold immense promise for a wide range of applications ranging from quantum optics to biomedical detection. As a broadly employed material platform for visible wavelengths, silicon nitride (SiN) has been used to demonstrate numerous passive components. Recently, the hybrid integration of gallium nitride (GaN) blue laser diodes (LDs) with SiN photonic integrated circuits (PICs) through flip-chip bonding has been presented, paving the way for large-scale manufacturing of visible photonic integrated lasers. Different applications impose distinct requirements on laser performance. For example, high-power lasers are essential for biological sensing and imaging, while quantum applications demand narrow-linewidth lasers. However, lasers emitted from LDs are typically either multiple longitudinal modes or single mode with the broad-linewidth, which is still far from fulfilling the stringent requirements of quantum applications. When LDs are coupled to resonators, a fraction of light from resonators is reflected to LDs induced by Rayleigh backscattering. If the frequency detuning and phase conditions are satisfied, the self-injection locking (SIL) will be introduced by this optical feedback, and lead to significant linewidth reduction.

In this project, we will investigate SIL between GaN LDs and SiN microresonators at the blue wavelength of 488 nm. The student will start with simulation and design of photonic components (including ring resonators and Fabry-Perot resonators) to study coupling rates and Q factors for variable device parameters. The designs will be fabricated at the cleanroom (optional). The student will then develop the optoelectronic measurement setup, and perform optical and electrical characterization of the resonators on SiN chips. Subsequently, the SIL will be implemented and the performance of different resonators will be compared with simulation results. Based on off-chip measurement results, the LDs will be finally integrated on SiN chips by flip-chip bonding to demonstrate hybrid integrated narrow-linewidth blue lasers.

The student will gain hands-on experience with photonics simulation/design, cleanroom experience (optional), measurement setup development, and device characterization. The candidate should have a strong interest in photonics, component simulation and optical experiments. The knowledge of lasers and photonic devices (e.g., microresonators) is a plus.

Master's degree: Master of Engineering Technology, Master of Science, Master of Engineering Science

Required educational background: Electromechanical engineering, Electrotechnics/Electrical Engineering, Nanoscience & Nanotechnology, Mechanical Engineering, Physics

Duration: 1 year

For more information or application, please contact the supervising scientist Han Wang (han.wang@imec.be).