Tunable silicon integrated quantum light source with on-chip FSR-free filters

Area of Science:

• Quantum optics
• Integrated photonics
• Materials science

Background:

• Quantum light sources (QLS) are crucial for quantum information processing.
• Silicon photonics offers a scalable platform for integrated quantum devices.
• Spontaneous four-wave mixing (SFWM) is a key process for generating quantum light.

Purpose of the Study:

• To design and fabricate a telecom band quantum light source (QLS) on a silicon photonic chip.
• To demonstrate the effectiveness of on-chip filtering for enhancing QLS performance.
• To explore the role of Free Spectral Range (FSR)-free filters in integrated quantum light sources.

Main Methods:

• Integration of a silicon waveguide as a nonlinear medium for SFWM.
• Fabrication of five narrow FSR-free bandpass filters using grating-assisted contra-directional couplers (GACDC).
• Demonstration of two filtering functions: tunable photon pair generation and on-chip pump filtering.

Main Results:

• Achieved two tunable outputs for photon pair generation with a 6 nm tuning range using GACDC filters.
• Demonstrated an on-chip pump filter that suppresses Raman noise photons.
• Showed enhanced QLS performance with the integrated pump filter compared to external filtering.

Conclusions:

• FSR-free filters are vital components for developing high-performance silicon integrated QLSs.
• On-chip filtering significantly improves the signal-to-noise ratio of quantum light generation.
• This work advances the development of practical quantum light sources on silicon platforms.