Photon Detector Signal Divider Delay Cancellation
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Solution Overview
Problem
Single photon detectors face challenges in distinguishing the weak signal from a single photon due to periodic variations in the output, which are often obscured by artefacts, leading to difficulties in accurate detection and high-frequency operation.
Innovation Solution
A photon detection system that divides the output signal into two parts, delays one part, and combines them to cancel periodic variations, allowing for enhanced signal detection without increasing the detector bias, enabling operation at higher frequencies and quasi-continuous detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the APD is biased to an extent where the avalanche current dominates the output signal, then the signal detection capability is improved, but the operating frequency is reduced to relatively low frequencies
Solution Approach 1:
The output signal is divided into two separate paths: one path processes the signal directly while the other path introduces a time delay. This segmentation allows the system to separate the signal processing from the periodic variations, enabling high-frequency operation while maintaining signal detection capability through subsequent combination of the two paths.
Solution Approach 2:
The delayed version of the output signal is fed back and combined with the original signal path. This feedback mechanism allows periodic variations to cancel out when the delayed signal is combined with the current signal, enabling the system to operate at high frequencies while maintaining accurate signal detection by eliminating the confounding periodic artifacts.
2Measurement precision
If the output signal is processed to remove periodic variations, then the signal clarity is improved, but additional processing components are introduced
Solution Approach 1:
A delayed copy of the output signal is created and combined with the original signal. This copying approach allows the system to use the signal itself to cancel out periodic variations, avoiding the need for complex external reference signals or sophisticated processing algorithms while achieving improved signal clarity.
Solution Approach 2:
The system uses its own output signal, delayed by a specific time, to cancel out the periodic variations in the signal path. This self-service approach eliminates the need for external reference sources or complex processing components, as the detector essentially corrects its own output using a time-delayed version of itself.
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
This approach effectively isolates the signal from a single photon, improving detection efficiency and allowing for high-frequency operation without synchronization requirements, enhancing the detection of single photons in various applications such as quantum cryptography and time-of-flight ranging.
Implementation Method 1
An absorbed photon generates an electron-hole pair in the APD
Implementation Method 2
upon separation can trigger an avalanche of excess carriers. This avalanche of excess carriers causes a macroscopic and detectable current flow thorough the APD
Implementation Method 3
delay means for delaying the second part with respect to the first part
Data Source
AI summary
A photon detection system including a photon detector configured to detect single photons, a signal divider to divide the output signal of the photon detector into a first part and a second part, wherein the first part is substantially identical to the second part, a delay mechanism to delay the second part with respect to the first part, and a combiner to combine the first and delayed second parts of the signal such that the delayed second part is used to cancel periodic variations in the first part of the output signal.