Elliptically polarized light obtained from tilted high-contrast grating VCSELs.

Area of Science:

• Optoelectronics
• Semiconductor devices
• Photonics

Background:

• Vertical-cavity surface-emitting lasers (VCSELs) are crucial for optical communication.
• Achieving stable, tunable polarization states in VCSELs is essential for advanced applications.
• Standard high-contrast gratings (HCGs) typically produce linearly polarized light.

Purpose of the Study:

• To realize ultrathin elliptically polarized VCSELs.
• To investigate the polarization characteristics of VCSELs with tilted HCGs.
• To explore the potential of these devices as tunable sources for chip-scale applications.

Main Methods:

• Fabrication of VCSELs with standard HCGs featuring tilted bars.
• Orthogonal polarization suppression ratio (OPSR) measurements.
• Numerical simulations to analyze polarization states and anisotropies.

Main Results:

• Successful realization of elliptically polarized VCSELs using tilted HCGs without chiral layers.
• Demonstration that reduced OPSR in tilted gratings is due to elliptical polarization, not degraded selectivity.
• Confirmation that polarization state is tunable by balancing intrinsic and HCG-induced anisotropies.

Conclusions:

• Tilted HCGs offer a method for achieving elliptically polarized VCSELs.
• These VCSELs provide integrated, wavelength-tunable sources suitable for chip-scale atomic devices.
• The findings advance the development of compact and versatile optoelectronic sources.