Wide operation range in-phase coherently coupled vertical cavity surface emitting laser array based on proton...

Area of Science:

• Optoelectronics
• Semiconductor Lasers
• Photonics

Background:

• Coherent coupling of Vertical Cavity Surface Emitting Lasers (VCSELs) is crucial for high-power, high-beam-quality laser sources.
• Achieving stable in-phase mode operation in VCSEL arrays is challenging due to fabrication complexities and thermal effects.

Purpose of the Study:

• To fabricate and characterize in-phase coherently coupled VCSEL hexagonal arrays using proton implantation.
• To investigate the stability and beam quality of these arrays under varying injection currents.
• To compare the performance of hexagonal arrays with square arrays for improved in-phase mode stability.

Main Methods:

• Fabrication of VCSEL hexagonal arrays via proton implantation.
• Experimental testing of near-field, far-field profiles, and emission spectra.
• Analysis of array performance under different injection currents (10 mA to 35 mA).
• Far-field simulation to validate experimental results.

Main Results:

• Stable in-phase single-mode operation was achieved from 10 mA (I(th)) to 35 mA (3.5×I(th)).
• The hexagonal array exhibited excellent beam quality with a far-field divergence angle of 2.5 degrees and 29% power in the central lobe.
• Hexagonal arrays demonstrated more stable in-phase mode compared to square arrays due to stronger coupling.
• Maximum output power of 4.9 mW was achieved under pulse wave conditions.

Conclusions:

• Proton implantation is a simple, low-cost method for fabricating coherently coupled VCSEL arrays.
• Hexagonal VCSEL arrays offer superior in-phase mode stability and beam quality compared to square arrays.
• Further performance enhancements are possible with improved thermal management, making this a viable alternative for coherent array implementation.