Structure of MMF-VCSEL. Credit: Sensors (2024). DOI: 10.3390/s24144700
A study led by researchers from the Changchun Institute of Optics, Precision Mechanics and Physics, Chinese Academy of Sciences, has revealed a new metal-dielectric film mode filter structure that allows for flexible control of the transverse modes of vertical-cavity surface-emitting lasers (VCSELs), demonstrating the potential of metal apertures for enhanced mode control within VCSELs. The study was published in the journal Sensors.
Conventional oxide-confined VCSELs often suffer from increased series resistance and reduced output power when operated in single mode. To overcome these limitations, researchers have proposed an effective mode filtering technique using metal apertures.
The researchers used COMSOL software to develop a finite element simulation model of metallic mode-filtered VCSEL (MMF-VCSEL).The simulation results showed that the mode control performance of MMF-VCSEL is highly dependent on the number of P-distributed Bragg reflector (P-DBR) pairs, the size of the metal aperture, and the size of the oxide aperture.
Specifically, when the number of P-DBRs is small, the lateral optical field is strongly confined within the metal aperture, but the confinement weakens as the number of P-DBRs increases.
When the metal aperture was smaller than the oxide aperture, the light scattering effect intensified as the distance between the two apertures decreased.
This resulted in increased mode discrimination and mode loss, and improved single-mode stability.When the metal aperture exceeds the oxide aperture, the optical modes in the VCSEL are primarily controlled by the oxide aperture. This revealed the complex interplay between the metal and oxide apertures that determines the optical field confinement and mode discrimination.
Additionally, the researchers introduced a new parameter, optical gain, to characterize the change in threshold gain of different transverse modes due to light scattering by the structure. By balancing the optical gain difference between the modes and the optical gain of the fundamental mode, they identified optimal structural parameters that improve both the single-mode stability and slope efficiency of MMF-VCSELs.
This metallic mode-filter VCSEL structure represents an advancement in optical mode control: by flexibly modulating the transverse modes, the researchers have demonstrated the potential for high-power single-mode VCSELs with improved performance characteristics.
This work highlights the important role that metal apertures play in enhancing mode control in VCSELs, which opens new avenues for developing high-performance VCSELs for a wide range of applications.
Further information: Jingfei Mu et al., “Simulation of mode control in vertical-cavity surface-emitting lasers with metallic mode filters,” Sensors (2024). DOI: 10.3390/s24144700
Courtesy of the Chinese Academy of Sciences
Citation: Researchers Simulate New Metal-Filtered VCSEL Mode Control (September 13, 2024) Retrieved September 17, 2024 from https://phys.org/news/2024-09-simulate-metal-filtered-vcsel-modal.html
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