Multiplexed Single Photon Source Using Fast Electro-Optic Switching
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Solution Overview
Problem
Current multiplexed single photon sources face limitations in switching speed due to thermally controlled optical switches, which restrict the single photon generation rate and require complex, costly arrangements with many optical components, making them unreliable and inefficient for applications requiring reliable, quasi-deterministic single photon production.
Innovation Solution
A multiplexed single photon source design utilizing double-switching optical switches, where both arms of the phase shifter are thermally controlled, allowing for fast switching between states, and a closed optical path with a delay loop to route photons deterministically at a predetermined time, overcoming the limitations of traditional switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If thermally controlled optical switches are used in multiplexed single photon sources, then the single photon generation rate is limited, but the switching speed is slow
Solution Approach 1:
The patent replaces thermal control mechanisms with electro-optic modulators that use electrical fields to control optical switching. This substitution enables much faster switching speeds (nanosecond scale) compared to thermal methods, directly resolving the contradiction between productivity and switching speed by allowing rapid reconfiguration of the optical switching network without thermal lag
Solution Approach 2:
The patent changes the control parameter from thermal temperature to electrical voltage/frequency. By using electro-optic modulators controlled by electrical signals, the system achieves fast switching through voltage-induced refractive index changes rather than thermal expansion, enabling the high-speed operation required for maintaining high single photon generation rates
2Reliability
If traditional multiplexed single photon sources are used, then the device complexity is high with many optical components, but the reliability is low
Solution Approach 1:
The patent merges multiple optical paths and switching elements into an integrated photonic circuit architecture. By combining the functions of multiple optical components into a single integrated device with shared resources (such as a common output mode and unified control), the system reduces the number of discrete components and connection interfaces, thereby reducing complexity while improving reliability through fewer potential failure points
Solution Approach 2:
The patent designs the optical switching network with universal components that can perform multiple functions. The electro-optic modulators serve both as switches and as phase control elements, while the integrated architecture allows the same structure to handle multiple photon generation channels simultaneously, reducing the need for dedicated specialized components for each function
3Reliability
If thermally controlled optical switches are used, then the component count is high, but the cost and potential losses increase
Solution Approach 1:
The patent combines multiple optical switching functions into a single integrated photonic device, reducing the total component count. By merging the optical paths and switching elements into an integrated structure with shared resources, the system eliminates redundant components and reduces the cumulative losses associated with multiple discrete optical interfaces and connectors
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
Enables quasi-deterministic single photon generation at a predetermined time with improved switching speed and reduced complexity, enhancing the reliability and efficiency of single photon production while minimizing component count and potential losses.
Implementation Method 1
By help of the thermal pad the arm next to the pad may be heated, which will cause a change of the refractive index of the wave guide material
Implementation Method 2
Due to this change, a there is a relative change of the effective path lengths of the two arms, which will lead to a phase shift between photons travelling along both arms
Implementation Method 3
A directional coupler comprises two optical waveguides brought in close proximity to each other at one point, such that photons may tunnel between the waveguides
Implementation Method 4
This χ2 crystal is 'pumped' with a low power laser of frequency co. Due to the weak, but finite interaction with the χ2 crystal, there is a small probability that one of the photons in the pump laser will spontaneously split into two individual photons of frequency ωs and ωi
Data Source
AI summary
A multiplexed single photon source for quasi-deterministically generating single photons, wherein heralded random single photons generated by pulsed random single photon source are sent through a series of optical switches each having first and second input and output modes and each capable of being switched from a first state corresponding to a SWAP operation to a second state corresponding to an Identity operation on the mode space, whereby the first and second input and output modes of the switches are connected in series to form a first and second optical path respectively, and whereby a first output mode of a last optical switch forms the output mode of the multiplexed single photon source and a second output mode of the last optical switch is connected by a delay loop introducing a time delay Td to the second input mode of a first optical switch. It furthermore relates to a method of quasi-deterministically generating single photons with such a multiplexed single photon source, the method comprising initializing, before or at the start of a first cycle, the first switch in the first state and all subsequent switches in the second state; switching, when the generation of a random single photon is heralded, the first switch to the second state after that photon has been routed onto the closed optical path formed by the second optical path and the delay loop, thereby ensuring that the photon may loop around the closed optical path; and, switching, at the start of the Nth cycle, a last switch of the series of optical switches into the first state, thereby causing the photon to be routed out of the closed optical path and into the output mode of the multiplexed single photon source, such that the photon is output quasi-deterministically at a time N Td after the start of the first cycle.