Coupled Resonator Photon-Pair Source for High-Purity Bright Output
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Solution Overview
Problem
Existing photon sources struggle to generate single photons deterministically while maintaining high spectral purity and brightness, often compromising one characteristic to improve the other, such as spectral filtering reducing photon pairs and heralding efficiency.
Innovation Solution
A photon-pair source with multiple coupled resonators, where the pump and photon-pair resonators have different sizes and quality factors, allowing coupling-induced resonance splitting to broaden the pump spectrum, enhancing spectral purity without affecting brightness, and enabling independent tuning for on/off control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If spectral filtering is applied to improve spectral purity, then spectral purity is improved, but photon pairs and heralding efficiency are reduced
Solution Approach 1:
The system is divided into two separate resonators: a pump resonator for generating photon pairs and a signal resonator for filtering and output. This segmentation allows the pump resonator to operate with broad spectral acceptance for high generation efficiency, while the signal resonator provides narrow spectral filtering for high purity, eliminating the need to compromise between the two competing requirements
Solution Approach 2:
The signal resonator acts as an intermediary between the pump resonator and the output waveguide. It receives photon pairs from the pump resonator, applies spectral filtering to improve purity, and then couples the filtered photons to the output waveguide, thereby mediating the trade-off between spectral purity and generation efficiency
2Device complexity
If a single resonator is used for both pumping and photon-pair generation, then device complexity is reduced, but spectral purity and brightness cannot be simultaneously optimized
Solution Approach 1:
The single resonator is segmented into two functionally distinct resonators: a pump resonator with quality factor Qp optimized for photon pair generation, and a signal resonator with quality factor Qs optimized for spectral filtering. This segmentation enables independent optimization of each resonator's parameters to simultaneously achieve high spectral purity and high brightness
Solution Approach 2:
Each resonator is assigned different local qualities (quality factors) suited to its specific function: the pump resonator has a lower quality factor for broader spectral acceptance and higher generation efficiency, while the signal resonator has a higher quality factor for narrow spectral filtering and high purity output
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution generates photon pairs with high spectral purity and brightness by broadening the pump resonance spectrum, reducing correlation between signal and idler photons, and allowing for independent tuning of the photon source, enabling deterministic generation of single photons.
Implementation Method 1
a first resonator coupled to the pump waveguide, where the first resonator and the pump waveguide are configured to couple the pump photons from the pump waveguide into the first resonator
Implementation Method 2
the second resonator and the first resonator may be configured to cause a coupling-induced resonance splitting in the second resonator or the first resonator to broaden the pump resonance spectrum
Implementation Method 3
The second resonator includes a non-linear optical material that causes spontaneous four wave mixing (SFWM) using the pump photons
Implementation Method 4
an output waveguide coupled to the second resonator, where the second resonator and the output waveguide are configured to couple the photon pairs from the second resonator into the output waveguide
Implementation Method 5
the two or more electrodes may be configured to apply a voltage signal at the tunable portion to cause a refractive index change in the tunable portion of the first resonator or the second resonator
Data Source
AI summary
Techniques disclosed herein relate to photon sources with high spectral purity and high brightness. In one embodiment, a photon-pair source includes a pump waveguide, a first resonator coupled to the pump waveguide to couple pump photons from the pump waveguide into the first resonator, a second resonator coupled to the first resonator, and an output waveguide coupled to the second resonator. The second resonator is configured to convert the pump photons into photon pairs. The second resonator and the first resonator are configured to cause a coupling-induced resonance splitting in the second resonator or the first resonator. The second resonator and the output waveguide are configured to couple the photon pairs from the second resonator into the output waveguide. In some embodiments, the photo-pair source includes one or more tuners for tuning at least one of the first resonator or the second resonator.