Combining in-situ lithography with 3D printed solid immersion lenses for single quantum dot spectroscopy

Area of Science:

• Nanophotonics
• Quantum Optics
• Materials Science

Background:

• Semiconductor quantum dots (QDs) are crucial for quantum information processing and optoelectronics.
• Efficient light extraction and precise localization of QDs are critical for their performance.
• Existing methods for QD manipulation and enhancement often lack deterministic precision.

Purpose of the Study:

• To develop a deterministic method for fabricating solid immersion lenses (SILs) directly onto pre-selected semiconductor quantum dots (QDs).
• To investigate the impact of these SILs on QD optical properties, including light extraction efficiency and localization accuracy.
• To analyze potential modifications to QD properties induced by the fabrication process.

Main Methods:

• Utilizing low-temperature in-situ photolithography for precise pre-selection of individual QDs with sub-2 nm accuracy.
• Employing femtosecond 3D direct laser writing to deterministically fabricate hemispherical SILs on selected QDs with sub-micrometric precision.
• Characterizing the optical performance and properties of QDs before and after SIL fabrication.

Main Results:

• Achieved deterministic fabrication of SILs on pre-selected QDs.
• Enhanced QD light extraction efficiency by a factor of 2.
• Improved QD localization accuracy to well below 1 nm due to enhanced signal-to-noise ratio and focused pumping laser.
• Observed modifications in QD properties, such as strain and variations in internal quantum efficiency, induced by the SILs.

Conclusions:

• The combined approach of low-temperature lithography and 3D laser writing enables deterministic SIL fabrication on QDs.
• This technique significantly boosts QD performance metrics, paving the way for advanced quantum devices.
• The study highlights the interplay between nanostructure fabrication and quantum emitter properties.