Injection-locked semiconductor laser array using a graded-index rod: a computational model

Area of Science:

• Optics and Photonics
• Semiconductor Lasers
• Computational Physics

Background:

• Monolithic laser arrays require precise coupling for optimal performance.
• Coupling mechanisms in such arrays are complex and influenced by optical components like GRIN rod lenses.
• Understanding these interactions is crucial for developing advanced laser systems.

Purpose of the Study:

• To develop and validate a computational model for simulating optical coupling between multiple laser emitters in a monolithic array.
• To investigate the role of a Gradient Refractive Index (GRIN) rod lens in mediating this coupling.
• To determine optimal array configurations for achieving efficient laser coupling.

Main Methods:

• Characterization of individual emitter modes using effective index waveguide calculations.
• Solving differential equations for ray propagation in a non-uniform refractive index medium via a Runge-Kutta algorithm.
• Tracing ray bundles through free space, the GRIN rod, and back to the array to calculate power transfer fractions.

Main Results:

• The computational model successfully predicted coupling coefficients for a five-emitter array.
• An optimal array position and orientation were identified, demonstrating full coupling of all five laser elements.
• Computed coupling coefficients were found to be commensurate with values needed for complete array coupling.

Conclusions:

• The developed model accurately simulates laser coupling in monolithic arrays mediated by GRIN rod lenses.
• The findings provide a new interpretation of previous experimental results, attributing them to injection locking facilitated by the rod lens.
• This work offers a valuable tool for designing and optimizing integrated photonic devices.