Wavelength tunable polarizer based on layered black phosphorus on Si/SiO₂ substrate

Area of Science:

• Optoelectronics
• Materials Science
• Nanotechnology

Background:

• Black phosphorus (BP) exhibits significant optical anisotropy, making it a promising material for optical devices.
• Two-dimensional (2D) materials offer unique properties for nanoscale optical applications.
• Fabry-Perot cavities can be utilized for wavelength-selective optical filtering and polarization control.

Purpose of the Study:

• To theoretically and experimentally design a black phosphorus-based reflective linear polarizer.
• To investigate the use of Fabry-Perot cavities for polarization control in the visible spectrum.
• To explore the potential of BP's optical anisotropy for achieving high extinction ratios.

Main Methods:

• Theoretical design and experimental fabrication of a BP-based polarizer on a Si/SiO2 substrate.
• Utilizing Fabry-Perot cavities to enhance polarization properties.
• Employing azimuth-dependent reflectance difference microscopy to measure optical anisotropy.

Main Results:

• A BP-based reflective linear polarizer was successfully designed and fabricated.
• Optical anisotropy of 1.58 was measured for a 96 nm BP film, corresponding to a ~9 dB extinction ratio at 690 nm.
• Achieved polarization wavelength regulation and high extinction ratio by optimizing BP thickness.

Conclusions:

• The study demonstrates a new method for designing nanoscale polarizers using anisotropic 2D materials like BP.
• Integrating BP films with cavity structures offers a modulation technique for optical anisotropy.
• These findings promote the application of 2D materials in integrated optoelectronics and system-on-chip devices.