QPCSEL design advances semiconductor lasers
A buried dielectric architecture could improve the flexibility and reliability of photonic crystal surface-emitting lasers while simplifying the development of new device geometries.
Researchers at the University of Illinois Urbana-Champaign have developed a quasi-periodic photonic crystal surface-emitting laser (QPCSEL) architecture designed to overcome fabrication and geometry limitations associated with conventional photonic crystal surface-emitting lasers (PCSELs).
PCSELs use a photonic crystal layer to produce high-brightness laser beams with narrow, circular spot profiles. However, conventional devices typically rely on air holes that can deform during semiconductor regrowth, affecting the uniformity and integrity of the photonic crystal.
The researchers instead embedded a solid silicon dioxide (SiO₂) dielectric structure within the semiconductor. The approach uses sub-micrometre, low-index dielectric features surrounded by high-index epitaxial semiconductor material, preserving the patterned structure during regrowth.
The team also replaced the conventional periodic refractive-index pattern with a quasi-periodic photonic crystal, providing greater flexibility to engineer the laser's optical properties and device geometry.
The researchers demonstrated photopumped lasing at room temperature from a partially periodic, buried-dielectric QPCSEL, with emission at 1.5 µm.
According to the team, the buried dielectric platform could allow different photonic crystal structures to be fabricated on the same substrate, potentially improving device flexibility and uniformity.
The technology could support the development of tunable and more reliable semiconductor lasers for applications including lidar, remote sensing and navigation. The researchers' next step is to demonstrate an electrically injected diode, which would move the platform closer to a practical semiconductor laser.
