Resonant-cavity-enhanced p-i-n photodetector using a high-contrast-grating for 940nm

Area of Science:

• Optoelectronics
• Nanophotonics
• Semiconductor Devices

Background:

• Resonant-cavity enhanced photodetectors (RCE PDs) are crucial for high-performance optical detection.
• Traditional top mirrors can be costly and limit device efficiency.
• High contrast gratings (HCGs) offer a promising alternative for mirror fabrication.

Purpose of the Study:

• To investigate two novel high contrast grating (HCG) designs for RCE PDs operating at 940 nm.
• To achieve high reflectivity (>99%) and explore the impact of grating period on device performance.
• To assess the potential of HCGs for improved manufacturing cost, quantum efficiency (QE), and novel functionalities.

Main Methods:

• Designed and fabricated novel HCGs as top mirrors for RCE PDs.
• Utilized a 36-pair AlAs/GaAs bottom mirror.
• Varied grating periods from 450 to 490 nm to tune optical properties like Full Width at Half Maximum (FWHM).

Main Results:

• Achieved top mirror reflectivity exceeding 99% with HCGs.
• Obtained FWHM values ranging from 0.2 to 3 nm, tunable by grating period.
• Demonstrated a resonator HCG design yielding a split responsivity spectrum with a 14 dB on-off ratio.

Conclusions:

• Broadband HCGs offer a cost-effective solution for RCE PDs with near-unity quantum efficiency.
• Resonator HCGs enable unique spectral splitting, paving the way for ternary systems and optical switches.
• These HCG-based RCE PDs show potential for polarization dichroism, diattenuation, and advanced optical switching applications.