Related Experiment Video
Updated: May 20, 2025
00:07
A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference
Published on: September 5, 2019
8.4K
Laser-written reconfigurable photonic integrated circuit directly coupled to a single-photon avalanche diode array
Giulio Gualandi1,2, Simone Atzeni2,3, Marco Gardina2
1Dipartimento di Fisica, Politecnico di Milano, Milano, Italy.
Light, Science & Applications
|May 16, 2025
Summary
This study demonstrates direct coupling of room-temperature single-photon detectors with photonic integrated circuits, achieving high detection efficiency for scalable quantum photonics. This innovation bypasses complex cryogenic systems and costly fiber alignments.
Area of Science:
- Quantum Photonics
- Integrated Optics
- Solid-State Devices
Background:
- Current quantum photonics experiments often use cryogenic single-photon detectors linked to photonic integrated circuits (PICs) via optical fibers.
- This approach faces scalability challenges due to cryogenic requirements and the complexity of fiber coupling.
- Removing optical fibers and cryogenic conditions is desirable for compact, cost-efficient, and scalable quantum systems.
Purpose of the Study:
- To report a novel method for directly coupling a femtosecond laser-written PIC with a room-temperature silicon single-photon avalanche diode (SPAD) array.
- To demonstrate the effectiveness of this direct coupling in terms of efficiency and robustness.
- To showcase the utility of this integrated system for characterizing quantum photonic devices.
Main Methods:
- Fabrication of a PIC using femtosecond laser writing (FLW).
- Development of a custom planar technology for silicon single-photon avalanche diode (SPAD) arrays operating at room temperature.
- Direct heterogeneous integration of the PIC and SPAD array without optical fibers.
Main Results:
- Achieved perfect coupling between the PIC and the SPAD array.
- Attained a system detection efficiency of 41.0% at 561 nm, the highest reported for directly coupled systems.
- Demonstrated robust coupling insensitive to misalignments, eliminating the need for costly alignment procedures.
- Successfully characterized a reconfigurable Mach-Zehnder interferometer using the integrated SPAD array.
Conclusions:
- The direct coupling of FLW PICs and room-temperature SPAD arrays offers a scalable, cost-efficient solution for quantum photonics.
- This approach simplifies system design and implementation, paving the way for compact quantum devices.
- The demonstrated high efficiency and robustness open new possibilities for advanced integrated quantum experiments.
